[Title will be auto-generated] by Nordic Road and Transport Research

No 1 · 2000

News from Denmark, Finland, Iceland, Nor way and Sweden

EPS as lightweight fill

page 4

Simulation for the road toll at the Öresund link

page 20

Editorial notes Nordic Road & Transport Research is a joint publication of six public road and transport research organisations in the Nordic countries, Denmark, Finland, Iceland, Norway, and Sweden. The main objective of the publication is to disseminate research results and news from the institutions, especially to researchers and decision makers. Each institution is responsible for the selection and presentation of the material from its own scope of activities. Nordic Road & Transport Research is published three times a year. It is regularly sent out, free of charge, to recipients selected by the five joint publishers. Free sample copies are also sent out on special request. Reproduction and quotation of the text are allowed if reference is made to the author and source. However, legislation regulates and restricts the right to reproduce the illustrations. Please contact the respective publishing institution for information. Advertising is not accepted. Correspondence about the contents of the publication: Please write to the author or to the respective publishing organisation. Requests for back issues, and notification of address changes: Readers outside the Nordic countries: please write to the Editor-in-chief at the VTI in Sweden. Readers in the Nordic countries: please contact the publishing institution of your country. Addresses: see back cover. The Editorial Board consists of the following representatives of the publishing institutions. Editor-in-Chief Sigvard Tim, Swedish National Road and Transport Research Institute Denmark Helen Hasz-Singh, Danish Road Institute Finland Kari Mäkelä, Technical Research Centre of Finland, Communities and Infrastructure Iceland Hreinn Haraldsson, Public Roads Administration Norway Helge Holte, Norwegian Public Roads Administration Harald Aas, Institute of Transport Economics

Production: VTI Information Place of publication: Linköping, Sweden Issue: 3,500 ISSN: 1101-5179

Volume 12 · No. 1 · March 2000

Danish Road Directorate (DRD) The Road Directorate, which is a part of The Ministry of Transport, Denmark, is responsible for development and management of the national highways and for servicing and facilitating traffic on the network. As part of this responsibility, the Directorate conducts R&D, the aim of which is to contribute to efficient road management and to the safe use of the network. The materials research component is carried out by the Danish Road Institute while other R&D activities – primarily safety and environmental research – are carried out by the Directorate’s operational departments.

Technical Research Centre of Finland (VTT), Communities and Infrastructure Communities and Infrastructure, employing a staff of 135, is one of the nine Operating Units of the Technical Research Centre of Finland (VTT), which has a total staff of 2,720. Research at this Operating Unit covers all aspects of transport, road engineering, geotechnology and urban planning. The unit has active international relations and a prominent role in these research areas on the national level.

Public Roads Administration (PRA), Iceland The duty of PRA is to provide society with a road system according to its needs and to offer service aiming at safe, unobstructed traffic. The number of employees is about 340. Applied research concerning road construction, maintenance and traffic and safety is to some extent performed or directed by the PRA. The authority with its Research and Development division is responsible for road research in Iceland.

Norwegian Public Roads Administration (NPRA) The Norwegian Public Roads Administration is one of the administrative agencies under the Ministry of Transport and Communications in Norway. The NPRA is responsible for the development and management of public roads and road traffic, as well as the Vehicle Department. This responsibility includes research and development of all areas related to road transport, and the application of R&D products.

Institute of Transport Economics (TØI) The Institute of Transport Economics is the national institution for transport research and development in Norway. The main objectives of the Institute are to carry out applied research and promote the application and use of results through consultative assistance to public authorities, the transport industry and others. The Institute is an independent research foundation employing about one hundred persons.

The Swedish National Road and Transport Research Institute (VTI) is responsible for research and development in road construction, maintenance, road traffic and transport, railroads, rail transport, vehicles, road user behaviour, traffic safety and the environment. The Institute is state-owned and has a total of 215 employees.

Cover Photo: Pierre Mens NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

C O N T E N T S Long-term performance and durability of EPS as lightweight fill ............... 4 Norwegian Public Roads Administration (NPRA)

Laser texture measurement of asphalt concrete ......................................................... 8 Danish Road Directorate (DRD) Bridge pavements – why do they last longer than road pavements? .. 10 Danish Road Directorate (DRD)

Accredited asphalt laboratory .................................................................................................. 12 Technical Research Centre of Finland (VTT), Communities and Infrastructure Cost-effective street pavements ............................................................................................... 14 Technical Research Centre of Finland (VTT), Communities and Infrastructure

Implementation of road accident countermeasures .............................................. 16 Institute of Transport Economics (TØI)

The VTI Wheel Tracking Test ........................................................................................................ 19 Swedish National Road and Transport Research Institute (VTI)

The Öresund Link between Sweden and Denmark ............................................... 20 Swedish–Danish co-operation Simulation model for the Öresund Link road toll station ................................. 21 Swedish National Road and Transport Research Institute (VTI)

Children with disabilities face major risks in traffic .............................................. 24 Swedish National Road and Transport Research Institute (VTI)

A N N O T A T E D

R E P O R T S

Danish Road Directorate (DRD) ............................................................................................................. 26 Technical Research Centre of Finland (VTT), Communities and Infrastructure) .............. 27 Norwegian Public Roads Administration (NPRA) ........................................................................ 28 Institute of Transport Economics (TØI) ................................................................................................ 29 Swedish National Road and Transport Research Institute (VTI) ............................................ 31

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

NORWEGIAN PUBLIC ROADS ADMINISTRATION (NPRA)

Long-term performance and durability of EPS as a lightweight fill Some 30 years of experience with Expanded Polystyrene (EPS) as a lightweight filling material in Norway have brought about both its wider use on a global scale and the introduction of a number of different design applications. In addition to reduced vertical loads, the advantages of using EPS may also include reduced horizontal loads, simplified designs, foundations laid on EPS and increased speed and simplification of construction work. This article describes practical experience in Norway with longterm performance (material behaviour, deformation and creep) and durability of EPS. Expanded polystyrene is a very stable compound in chemical respects and experience has proved that no decay of the material should be expected when placed in the ground and protected according to the present design guidelines. Since the first road insulation project with EPS was performed in 1965 and the first EPS light4

EPS embankment for the city tram line in Oslo (NRRL in the background) with vertical walls as an alternative to a bridge.

weight embankment was constructed in 1972, we have monitored structures of this type with periodic inspections and measurements focusing on the following aspects: • Material behaviour (compressive strength, water absorption and decay) • Deformation (total and in layers of EPS and creep effects) • Stress distribution • Reduced lateral pressure • Bearing capacity.

Fill location

Testing frequencies

Since the first project was completed in 1972, several tests have been carried out in order to monitor possible changes in the material. In this connection, samples have been retrieved from existing fills to be checked for possible changes in strength and unit density. The testing frequency is shown in Table 1. Also variations in water absorption of blocks placed in drained, submerged or semisubmerged positions have been observed. In order to

Constructed

Test samples retrieved

Year

No. of years after construction

National road 159 Flom bridges

1972 / 73

National road 154 Solbotmoan

1975

County road 91 Lenken

1978

County road 26 Langhus

1977

National road 610 Sande – Osen

1982

Table 1. Testing frequencies on EPS embankments. NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

NORWEGIAN PUBLIC ROADS ADMINISTRATION (NPRA)

be performed on the same specimen twice, the results clearly indicate that there are no signs of material deterioration over the total timespan of 24 years. If a tendency toward change is to be noted, this would suggest a slight increase in material strength. Unit density

Excavation of a 24-year-old EPS block from the first EPS embankment at Flom bridge (1972).

determine the stress distribution within blocks and fills, both laboratory and field tests have been performed. Finally, load creep effects have been observed both in the laboratory and on existing fills. Material strength

According to our specifications, the design compressive strength of EPS blocks has been set at a minimum of σ = 100 kPa unless otherwise specified. One major indicator of possible deterioration of blocks with time is a decrease in the material strength. The strength tests performed on retrieved samples from fills after lying in the ground for up to 24 years are shown in Figure 1 as a function of dry unit density and compressive strength. Bearing in mind the criteria mentioned

Compressive strength (kN/m2)

140

(9)

130

Flom Lenken Normal qual.

(12)

(21)

120 110 (7) (6)

(9)

100 90

(0)

(4)

Water content (volume %)

(7) (0) Design line

Solbotmoan Langhus Lenken

40 60 80

( ) Year after construction

20 22 24 Density dry (kg/m3)

Figure 1. Compressive strength of samples retrieved from EPS fills.

5 (4 _ 9)

10 (20)

20 40

Highest ground water level

Sande - Oset Solbotmoan

GW level

100

Depth below top EPS (cm)

Solbotmoan Langhus Sande

Depth below top EPS (cm)

150

above for accepting blocks to be placed in a fill, all test results give values of compressive strength above σ = 100 kPa, except for one test. The deviating test was performed on samples taken from the first fill shortly after it was completed in 1972, and is more an indication of variations in material quality of EPS with the production process used at that time. Nevertheless, the observed value is within the accepted statistical variations in material strength. From Figure 1, it may also be observed that the majority of tests show values of compressive strength in relation to unit density above that of a normal quality material. Although it is naturally impossible to make exact comparisons between material strength at the time of construction and for some time afterwards since tests cannot

A number of tests, mainly on small samples in laboratories, have been performed in several countries in order to study water absorption effects. Both the quality of these tests and the results vary. Tests performed on samples retrieved from existing fills in Norway are in agreement with some of the laboratory tests. Tests performed on samples retrieved from three EPS fills placed in a drained position, i.e. blocks located above the highest groundwater or flood level, all show water contents below 1% by volume after almost 30 years in the ground (Figure 2). Furthermore, there is hardly any change in the water content with time. Samples retrieved from the outer parts of blocks facing the surrounding soil may have a higher water content, but only 500 mm further into the block the water content is again below 1% by volume. In blocks which are periodically submerged, water contents of up to 4% by volume have been measured in the same period. In permanently submerged blocks, measured water contents have reached values of almost 10% by volume (ρ = 90 – 95 kg/m3 ) with some increase over the years. The water content decreases rapidly above the water table and shows values for drained conditions only some 200 mm

Lab. data Japan ( ) Years after construction

(9)

100

Figure 2. Typical drained situation from three EPS fills.

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

Figure 3. Typical water content in submerged EPS blocks. 5

NORWEGIAN PUBLIC ROADS ADMINISTRATION (NPRA)

above the highest water level. Time (days)

Deformation and creep effects in EPS constructions

500

1000

1500

Load conditions: σv = 52.5 kN/m

0.5

Strain (%)

Both full scale and laboratory tests have been performed with regard to material creep and stress distribution. In general, only about 30% of the material strength is utilised for supporting dead loads, i.e. qdw < 30 kPa for normal strength blocks (σ =100 kPa). In certain special cases, higher stresses related to dead loads have been used. In a laboratory test at the Norwegian Road Research Laboratory, a test fill with a height of 2 m using normal size blocks and compressive strength σ = 100 kPa has been loaded to a value of qdw = 52.5 kPa and the resulting deformations observed over a period of three years. The results are shown in Figure 4 together with calculated deformations to be expected according to the theories introduced by Magnan & Serratrice. As may be seen, the observed deformations are only about half the calculated values and creep deformations with time are also much smaller. Løkkeberg bridge is a single lane Acrow steel bridge with a single span of 36.8 m crossing road E6 close to the Swedish border. The bridge was built in 1989

EPS density : 20 kg/m3 EPS embankment height : 2 m

1.0 1.5

Profile A-A

10.5 t

NRRL test hall Magnan & Serratrice

2.0

Earth pressure cells

2.5

Figure 4. Deformation / creep in the test fill.

as a temporary improvement (3–5 years) in traffic safety until the completion of a new motorway between Norway and Sweden. Due to low bearing capacity and expected large settlements, lightweight fill materials (EPS) were considered for use in the embankments adjoining the bridge. The structure provided an opportunity to place the bridge foundation directly on top of the EPS fills (height 4.5 and 5 m) on both sides as an alternative to placing the bridge abutment on piled foundations. Since the bridge was temporary and pos-

sible deformations could be adjusted during the period of operation, it was decided to carry out the project as a full scale test. Three different qualities of EPS material strength have been used with design strengths as shown in Figure 6. In the upper layer, only 25% of the material strength has been utilised, while in the bottom layer the corresponding figure is 60%. The bridge is still in operation today 10 years after completion. No signs of cracks or uneven deformation have been observed. Løkkeberg bridge has provided a good

Full scale test at Løkkeberg bridge built on two EPS embankments. Long-term monitoring of deformation, creep and stress distribution

Telescopic rods

σ = 240 kPa 0.8 cm σ = 180 kPa

EPS

5.6 cm 6.2 cm σ = 100 kPa 3.7 cm

Gravel/sand Clay

Figure 5. Construction of the abutment on the EPS embankment at Løkkeberg bridge.

Figure 6. Deformations in EPS embankment at Løkkeberg.

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

NORWEGIAN PUBLIC ROADS ADMINISTRATION (NPRA)

Stress distribution

Time

1989 1991 1993

1995

1997

1999

Settlements (cm)

Total settlements Settlements in clay Deformations in 4.5 m EPS Deformation in lowest EPS layer

Figure 7. Creep deformation at Løkkeberg.

opportunity for monitoring long-term performance such as creep and stress distribution in an EPS embankment. After 10 years in service, measurements show only small deformations of 6 cm (1.3% of the EPS height) in the EPS embankment. Most of the deformations occurred during the construction period and only minor creep effects have been measured. Creep deformations as an average and creep deformations for the lowest EPS layer (6.5% of the layer thickness) are shown in Figure 7 for a period of 10 years.

Attempts have been made to evaluate the stress distribution in EPS blocks based on stress observations from the test hall experiments, and stress observations at the Løkkeberg bridge. Stresses between blocks are, of course, difficult to measure and the results obtained vary considerably. In general, measured stresses are, however, relatively low and indicate that the outer perimeter of the stress bulb may lie within a slope with a gradient of 2:1 measured from the outer edge of the loading area. However, local stress concentrations may occur depending on the stiffness of the loading area and possible load eccentricities. Durability

From the observations discussed above, it may be fair to conclude that no deficiencies are to be expected from EPS fills placed in the ground over a normal life cycle of 100 years. This should hold true, provided proper allowance is made for possible buoyancy forces resulting from fluctuating water levels, the blocks are properly protected from accidental spillages of dissolving agents and the

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

applied stress level from dead loads is kept below 30–50% of the material strength. References Frydenlund T. E. and Aabøe R.: Expanded Polystyrene – The Light Solution. International Symposium on EPS Construction Method, Tokyo 1996. Aabøe, R.: Deformasjonsegenskaper og spenningsforhold i fyllinger av EPS (Deformation and stress conditions in fills of EPS) Internrapport 1645. Public Roads Administration 1993. Skuggedal H. and Aabøe, R.: Temporary overpass bridge founded on expanded polystyrene. In: Proceedings X ECSMFE, Florence May 1991, Volume 2. Magnan & Serratrice: Propriété mécanique du polystyrène expansé pour ses application en remblais routier. Bulletin LCPC. France 1989. Roald Aabøe Senior engineer Public Roads Administration / Norwegian Road Research Laboratory.

DANISH ROAD DIRECTORATE (DRD)

Laser texture measurements of asphalt concrete Measurements of the macrotexture of road pavements with the aid of laser technology has shown to be a reliable and useful technology both in the laboratory and in routine measurements performed on inservice pavements. Comparison of macrotexture and friction measurements has shown that it is possible to achieve a good correlation, which makes it possible to pinpoint road sections where friction problems may occur. A screening process using laser technology to measure the macrotexture properties of the pavements supports a more flexible network of friction measurements since the macrotexture measurements can be performed at normal traffic speeds up to 80 km/h. However, the present technology for laser measurements does not allow this technology to replace the physical method of measuring friction. Tests performed by the Danish Road Institute have shown that the pinpointing of potential road sections with possible friction problems may possibly be optimised by introducing another parameter for the pavement texture which can be combined with the ISO specified Mean Profile Depth (MPD). Laboratory tests have shown that it is possible to establish the texture characteristics of an asphalt pavement from the measured texture profile. The texture characteristics are determined by the Power Spectral Density, Slope Variance and MPD. The method of determining the texture characteristics may offer the following potentials for innovation. • The method makes it possible to establish requirements for the texture characteristics of asphalt pavements based on laboratory tests.

Sample No.

Material

Texture description

Colour

Asphalt

Coarse

Small colour variation black/grey

Asphalt

Fine

Small colour variation black/grey

Asphalt

Smooth/flat

Large colour variation black/white

Table 1. Description of the three asphalt samples.

• The measurements of friction properties of new asphalt materials can be investigated in the laboratory through precise analysis of the texture characteristics of the material. • The method could enable the texture and friction properties of trial pavements to be closely defined before the pavements are constructed. Studies of the changes in texture characteristics due to polishing of the pavement by traffic can be made in great detail. Climatic influence on the pavement surface may result in bleeding and hence cause significant changes in texture and friction. Both these conditions can be investigated in the laboratory or by in situ measurements. Measurements of the macrotexture of asphalt cores in the laboratory

For the laboratory tests, asphalt cores with a diameter of 10 cm taken from in-service pavements were used. During the measurements, the cores were placed in a holder made from a 10-cm core drill. In order to perform the tests under controlled speed conditions, the holder with the asphalt core was placed in a lathe, which ran at a constant speed. The asphalt cores used in the test were

selected on the criterion that it was visually possible to distinct the cores from each other. The samples were described as follows: Figure 1 shows the measurements of the texture profile of the three asphalt cores. The distance between the measuring points is 0.252 mm. The figure shows that there is a significant difference between the texture profiles. Sample 1 shows that the texture profile has a larger variation and also shows a larger texture than samples 2 and 3. The texture in sample 2 is characterised by not having a large texture, but shows certain sharpness for the smaller textures. For sample 3, the texture profile shows amplitudes between samples 1 and 2. However, it is not possible to evaluate the sharpness of the texture for this sample. On the texture profiles measured from the three asphalt samples, the Mean Profile Depth (MPD) is determined on the basis of the ISO 13473-2 standard. Determination of the MPD gave the result shown in Table 2.

Sample

MPD in mm

2.2

0.3

0.7

Table 2. Calculated MPD based on ISO 13473-2.

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

DANISH ROAD DIRECTORATE (DRD)

Sample 1

Sample 2

Sample 3

Sample 1

Sample 2

Sample 3

Photos of the three samples used in the test.

100

150

200

250

300

2 50

100

150

200

250

300

1 0

100

150

200

250

300

-1

-2

-3

-4

devices having a lower slip percentage. In order to investigate the smaller textures and the sharpness of the surfaces of the samples, the slope variance of the profile is calculated using the interval between measuring points (0.252 mm) as the basic length. By calculating the slope variance for each of the samples, the following result is obtained:

be beneficial to include a parameter such as slope variance of the texture profile, together with calculation of the MPD. Both parameters are easily implemented as algorithms in a routine measuring system for texture measurements and will make it possible to provide information on the texture conditions which can be used in an optimised procedure for pinpointing road sections with poor friction conditions. This article is based on Eksternt notat 9 “Måling af asfaltbelægningers tekstur i relation til friktion” available from The Danish Road Institute.

-1

Figure 1. Measurements of the texture profiles.

As seen from Table 2, the calculated MPD corresponds very well to the visual evaluation with a characteristically higher MPD value for sample 1. If the friction condition of the pavement is to be evaluated on the basis of the MPD alone, sample 1 should have a significantly better friction condition than the two other samples. Evaluating samples 2 and 3, the visual investigation left the impression that sample 3 seemed to be smoother on the surface than sample 2, due to the fact that a larger part of the surface of sample 3 was covered with bitumen and the stones seemed to be polished. Detailed investigation of the samples

One of the problems with the calculated MPD is that it is determined on 100 mm intervals of the surface. This means that neither the smaller texture nor the sharpness of the asphalt surface is taken into account. In particular, the sharpness or the lower ranges of the texture have a significant influence on friction measurements, especially those performed with friction

Sample Slope variance SV

0.577

0.189

0.138

Table 3. Calculated slope variance of the three samples.

From Table 3, it can be seen that sample 2 has a larger slope variance but a smaller MPD than sample 3.

Author: Bjarne Schmidt Language: Danish with English abstract

Performing a screening process using laser technology

Based on the examples shown above, it is considered that in order to perform an optimised screening process on the friction condition of a road network, it would

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

DANISH ROAD DIRECTORATE (DRD)

Bridge pavements – what makes them long-lasting? In Denmark, bridge pavements have a long life. One reason for this is stringent specifications, extensive control of materials and construction, and frequent supervision.

bridges as protective layer and basecourse, and on steel bridge decks also as wearing course.

Bridges are required to have long lives partly because of problems with traffic bottlenecks that occur while repairs are being carried out. Furthermore, bridge pavements are laid on top of waterproofing, which imposes special demands on stability and density.

For other types of pavement for bridges, the specifications are drawn up on the basis of the standards for road pavements. Since the aim is to achieve long life and high density of the bridge pavements, there are no specifications for soft asphalt concrete. This type of pavement is used only on smaller, less important bridges using the wearing course from adjacent roads.

In the standards for bridge pavements, two types of pavement are mentioned which are used only on bridges. One type is an open-graded asphalt concrete, which is an asphalt concrete with a high content of voids (17–20%). This is used as a drainage layer with a thickness of 15–20 mm between the waterproofing and the pavement, in order to drain any water which may seep down from the pavement above and to relieve the waterproofing from water pressure. The second type of pavement is an asphalt concrete (ABM), modified compared to traditional asphalt concrete, with a low air void content (less than 4% by volume). ABM is used as a protective layer between the drainage layer and the wearing course. This is a very dense asphalt concrete with a high percentage of large aggregate in order to ensure stability and low permeability. Mastic asphalt

Although mastic asphalt has been used as a road pavement, there are no specifications for this type of pavement in the standards for road pavements. On the other hand, the standards for bridge pavements contain specifications for mastic asphalt as a protective layer and wearing course, which ensures properties which are appropriate for bridge pavements. Mastic asphalt is used on concrete and steel 10

Asphalt concrete

As regards asphalt concrete, the specifications are based on the general requirements for road pavements, but the requirement on the average void content has been increased from 9% to 7%. Gap-graded asphalt concrete for wearing courses is not included in the standards for bridge pavements, since the requirements are so wide that the demands for a bridge pavement can be obtained on that basis. Instead, the aim is to provide a stone mastic asphalt on those bridges where resistance to rutting and a long life with intensive traffic are required. Stone mastic asphalt

Stone mastic asphalt was used in the late seventies on an experimental basis in Denmark. However, this type of wearing course was chosen as wearing course on Vejlefjord Bridge in 1980 and due to a lack of experience, it was decided to let the contractor’s specifications apply. These specifications, together with the experience gathered from this pavement, were used as the basis for the current requirements for stone mastic asphalt in the standards for bridge pavements. Experience from the bridge across

PHOTO: DANISCH ROAD INSTITUTE

Special pavements for bridges

Other types of pavement

Vejlefjord Bridge in 1997 after 17 years of heavy traffic. The wearing course is being replaced in 1999 and 2000 after a lifetime of 19 and 20 years, where 10–15% of the surface is too open and has started to deteriorate.

Vejlefjord has shown that deterioration starts in the most open areas as loss of aggregate, which ultimately results in disintegration of the surface. After 19 years of heavy traffic, deterioration in the 10– 15% of the most open area is so advanced that the pavement is currently being replaced. It is presumed that the remaining 85–90% of the pavement has a remaining life of some five years or more. On the Alssund Bridge, the same type of pavement was laid in 1981 as that from the Vejlefjord Bridge, but greater care was taken to avoid open areas on this pavement. However, after 15 years of use, the pavement had become more open, but without loss of aggregate. The surface of the open areas has in recent years been sealed with bitumen emulsion and sand dusting. The pavement is now in such good condition that a further life of 10– 15 years can be expected. Based on the experience obtained from the Vejlefjord Bridge and the Alssund Bridge, the group revising the standards for bridge pavements has increased the demands on compaction and permitted

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

DANISH ROAD DIRECTORATE (DRD)

Asphalt roadbase

In general, asphalt roadbases are not used on bridges. They may be used in tunnels with a thick covering layer. In such cases, the standards for road pavements apply. Control

The long life of bridge pavements is assumed to be due to a combination of a stringent standard, extensive control of materials and construction, and frequent supervision. Thus, not only a better but also a more uniform product is achieved. The latter has a great influence, since pavement life is generally detemined by the poorest 10–15% of the pavement. The control of bridge pavements is stricter compared to road pavements, since the frequency of core sampling is increased for the purposes of material control. Also, the binder is recovered and tested daily to provide documentation that the specifications are fulfilled. Further, the heights of all cores are measured. This requirement does not apply to road pavements. Furthermore, there is a requirement on bridge pavements regarding compaction

and voids 20 mm from the joint for all types of asphalt, as well as for protective layers and wearing courses, since experience has shown that deterioration often starts here. There is no compaction requirement on hot-mix asphalt for road pavements closer than 25 cm from joints. The control of bridge and road pavements is based on first party control (contractor’s control), although the road owner frequently – and always in construction of larger bridges – performs an additional random sample control. In all cases, the road owner must obtain material samples during construction so that any disputes can be settled by examination of the samples. Future improvements

Despite the results obtained on bridge pavements to date, there is still a consid-

erable potential for improvement. Thus the results from the SHRP project have still not been incorporated in the standards; neither have the results obtained from research projects in recent years been implemented fully. The experience obtained from the bridge across the Great Belt is also expected to provide useful input for future standards. Further improvements in bridge pavements can therefore be expected in the coming years, so that a service life of 30 years is within reach.

Article specially written for Nordic Road & Transport Research by Vibeke Wegan, Senior Researcher, Danish Road Institute. Mrs. Wegan can be reached for further information on +45 46 30 7000 or e-mail: viw@vd.dk

PROPERTY

ROAD PAVEMENT

BRIDGE PAVEMENT

Compaction Tolerance

95%

97%

Void percentage Tolerance

7.0%

6.0%

Passing 5.6 mm sieve

30–50%

30–45%

Passing 2 mm sieve

18–30%

14–24%

Passing filler sieve

5–12%

>8%

Void percentage in aggregate

16%

>17% (rock granite), 18% (steel slag)

78–93%

80–95%

Bitumen filling

Comparison of the requirements formulated for stone mastic asphalt (SMA11) in bridge pavements in relation to road pavements.

PHOTO: DANISCH ROAD INSTITUTE

voids (compared to demands for road pavements). In order to ensure resistance to rutting, the amount of large aggregates and filler has been increased and there are demands on a high void content in the aggregate. All these demands automatically ensure a higher bitumen content, which is an important factor for a long life.

Alssund Bridge: After 15 years of traffic, the wearing course has become open. After sealing, the surface is now in good condition and is expected to have a life of 30 years.

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

Accredited asphalt laboratory A guarantee of highly qualified testing services Around the world, customers seek reassurance that the asphalt or materials they purchase will meet their expectations. Increasingly, this means a direct need to have the product tested or measured by an accredited laboratory. VTT Communities and Infrastructure in Finland is renowned for its road and foundations engineering services, road materials research, road measurements and laboratory testing. VTT has played a key role in several major research programmes in Finland like ASTO (Asphalt Pavement Research Program 1987–1993) and TPPT (The Road Structures Research Program 1994–2000). Development of a quality system for asphalt testing services at VTT started back in 1989 with the publication of the first quality control manual. The first accreditation for principal asphalt tests was granted to the laboratory by the Finnish 12

Accreditation Services (FINAS) in 1995. Since then the VTT asphalt testing laboratory, designated number 028T, has had the right to use the accreditation logo in its accredited testing reports. Accreditation is based on the international quality norms EN 45 001 and ISO Guide 25. In 1999 the accreditation was renewed and expanded to cover additional tests for geotextiles. What accreditation means

Before a laboratory is recommended for accreditation, the assessment process involves evaluation by special technical experts of all proposed tests and measurements to be done in accordance with the norm requirements mentioned above. A laboratory can have all or part of its testing evaluated by an accreditation body. The accreditation process involves a thorough assessment of all the elements of the laboratory that contribute to the production of accurate and reliable test data.

Figure 1. Accredited ECODYN retroreflectivity testing of road markings.

These elements include staffing, training, supervision, quality control, equipment, recording and reporting of test results and the environment in which the laboratory operates. Direct benefits of accreditation

The value of accreditation is emphasised, especially with respect to road measurements bound to the safety aspects of trafficked roads. These include the night visibility of road markings (Figure 1) or the trafficability, rut depth, roughness and evenness of road surfaces (Figure 2). For material companies, asphalt paving contractors, the Finnish National Road Administration and the other authorities it is important to show unequivocally that the safety characteristics for road users have been tested by confirmed methods and with the calibrated equipment of the

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

PHOTO: TIMO UNHOLA

TECHNICAL RESEARCH CENTRE OF FINLAND (VTT), COMMUNITIES AND INFRASTRUCTURE

accredited testing laboratory. Accreditation also gives a good basis for product development of new materials for road construction, like synthetic geotextiles. In this connection, in European markets it is already becoming commonplace to use tests served exclusively by accredited laboratories. Adoption of the international accreditation norms (EN 45 001, ISO Guide 25 and ISO 17 025) has helped many countries demonstrate the competence of their laboratories through international “round robin” reference test procedures typically required for accreditation.

Towards future accreditation

Accreditation of testing services at VTT asphalt laboratory is to be expanded to

Figure 2. Accredited testing of PTM (Service Level Measurements) of road surfaces; rut depth, evenness and IRI value.

form an integral part of the total quality system, and as such will be a significant management and leadership tool for the laboratory. Accreditation has provided very positive feedback since the first accreditation in 1995. Customers in particular are satisfied that the laboratory operates in accordance with international competence criteria for testing laboratories. It has also been noticed that an accredited testing system gives the laboratory ready means for serving customers, based on their needs, through reliable testing. The accreditation of VTT is very important for the road sector, as VTT has the only accredited asphalt laboratory in Finland. As the laboratory enters the new millennium, the new harmonised accreditation norm ISO 17 025 will help meet increasing testing demands both in the field and in laboratory, enabling the laboratory to continue serving customers with the best available, state-of-the-art, and confirmed methods. More information about VTT Communities and Infrastructure can be found on the website at www.vtt.fi/tpa.

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

PHOTO: TIMO UNHOLA

Accreditation at VTT includes the following main methods: - Softening point of bitumen - Penetration of bitumen - Breaking point Fraass of bitumen - Nordic abrasion value of aggregates - Point load index of aggregates - Impact value of aggregates - Specific surface area, nitrogen adsorption of aggregates - Shape value of aggregates - Thickness and bulk density of asphalt paving mixtures - Air voids content of asphalt pavement - Wear of asphalt pavement by studs, SRK method - Indentation value of mastic asphalt and hot road marking - Rut depth and evenness of road surfaces - Heat stability of hot road marking materials - Colour and luminance factor of road markings When characterising geotextiles as shown in the wide width tensile test (Figure 3) above, the following additional main tests for geotexstiles in earth construction can be carried out at VTT: - Characteristic opening size of geotextiles - Static puncture test - Cone drop test - Determination of water permeability

PHOTO: TIMO UNHOLA

Characteristics tested by accredited methods

Figure 3. Accredited strain strength measurement of geosynthetic products.

Article specially written for NR&TR by Petri Peltonen, tel. +358 9 456 4987, fax +358 9 463 251, e-mail petri.peltonen@vtt.fi

TECHNICAL RESEARCH CENTRE OF FINLAND (VTT), COMMUNITIES AND INFRASTRUCTURE

Cost-effective street pavements The Street Structures and Pavements Research Programme (KRP) is a six-year project aimed at developing street maintenance (1995– 2001). The project aims at increasing the cost-efficiency of road maintenance, while also increasing environmental safety and living comfort in the area. The development of pavements has been an important part of the KRP project. New materials and pavement solutions have been developed and selection and design criteria have been specified more clearly in order to reach the set goals.

Built-up areas have their own characteristics, which pose special demands on street pavements and structures. The conditions on and needs of low traffic access roads differ especially from those that require consideration in the maintenance of public roads. This research programme focuses on three themes – pavements, pavement structures and cables. The studies in the project are based on earlier practices and the experiences obtained through them, as well as on information recently provided by large-scale national road maintenance research programmes. The need for development was surveyed by having municipalities voice their problems, which were then combined to form larger areas for research. The project experiences obtained through test building have provided researchers with new data. Municipalities were already actively developing their road and street maintenance operations before the programme. The projects have, however, been a diverse bunch. Lack of coordination and proper monitoring has made it impossible to integrate nationally the available resources and know-how. Thus one aim of the project has been to integrate resources and centralise development work to ensure

PHOTO: RISTO ALKIO

Development of street structures and pavements in the 1990s

the solution of problems and the development of new methods. High-quality pavements with low annual costs

During the last five years, test building has been carried out at close to twenty sites in connection with seven research themes. The development of street pavements has played a significant part in the KRP project, and has been closely linked to the updating of street pavement documents that took place at the same time. The pavement research has been directed and carried out by a working group which included representatives of the Association of Finnish Local and Regional Authorities, cities and industry. The aim of the project has been to increase the overall cost-efficiency of street paving operations. This means looking for the solution with the lowest annual costs, not forgetting factors that cannot be measured directly in monetary terms. The overall cost-effectiveness of a paving operation

Pavement material research by fixing asphalt test slabs to lanes.

is therefore affected, among other things, by the pavement’s • durability life and annual costs • safety to the environment and sustainable construction • living comfort and cityscape. Selection of pavement solutions is based on the following principles: 1. Selection of materials and a pavement solution to suit the traffic load at each individual site. When selecting a pavement, the use of applications with overly high performance requirements must be avoided. However, it may be economically expedient to combine several sites located close together and pave them all in one go. The pavement type and material used will then be selected to suit the application with the highest performance requirements.

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

TECHNICAL RESEARCH CENTRE OF FINLAND (VTT), COMMUNITIES AND INFRASTRUCTURE

2. Minimising the long-term costs of pavement maintenance by planning maintenance actions and the order in which they are carried out (definition of pavement maintenance actions). The cost of a single pavement maintenance action is not the definitive factor in selecting a suitable maintenance method. The maintenance actions are planned to ensure the lowest possible annual costs in the long run. 3. Quality, environmental factors, appearance and other values that cannot be measured solely on a purely financial basis. According to the properties of each individual site, other demands besides the lowest possible annual costs can also be set for the wearing course of streets at each location, such as appearance in residential areas or minimising traffic noise on thoroughfares. The most significant findings of the research conducted by the KRP project’s pavement working group are as follows: • Asphalt mixtures AB 8 and SMA 8, which have a maximum grain size of less than 11.2 mm, have a high wear resistance if designed and used properly. Asphalt mixtures with maximum grain size < 11.2 mm are perfect for use in thin wearing courses. • Stone mastic asphalt (SMA) has a higher wear resistance than asphalt concrete (AB). Stone mastic asphalt also has other good qualities: high stability, good appearance, low level of traffic noise and good friction. • The Nordic abrasion test is well suited for evaluating the mineral aggregates used in street pavements. It has a high correlation with pavement wearing. • The impact of the aggregates’ flakiness index on wear resistance is not as significant as the impact of the aggregates’ strength or maximum grain size.

Finnish Asphalt Specifications 2000

Guidelines and documents used to regulate the paving of streets Contract Documents 2000 Guide for Selection of Asphalt Pavements 2000

Guidelines and documents used to regulate the paving of streets and smaller targets.

• The aggregates’ flakiness index affects the aggregates’ optimum binder content. • There are no quality barriers which would prevent the reuse of milled and crushed asphalt in built-up areas. Recycled asphalts are homogeneous and fulfil the quality requirements. • Considering their durability levels, asphalt concrete (AB) and soft asphalt (PAB) pavements can be used in low traffic access roads. When selecting a type of pavement or material, one should take into account the conditions and amount of traffic at individual sites to ensure selection of the most economically feasible alternative. When the project is completed, its findings will be introduced and utilised through guidelines and documents used to regulate the paving of streets and smaller targets. The documents are presented in the figure above. The documents will be used by building contractors, i.e. municipalities, small industries and trade, real estate property holders, ports and terminals and the operators of private road networks. The docu-

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

ments can also be of assistance to branches of industry connected with street construction, such as asphalt contractors and the construction material industry. In addition to the reports, guidelines and documents, the findings of the KRP project will also be made public through outlines given at seminars to key figures in the field and through articles in technical journals.

Publications (in Finnish): Asfalttipäällysteen valintaohje 2000. Kadut, pihat ja erityisliikennealueet. (Guide for selection of asphalt pavements 2000 – streets, courts and special traffic areas). Association of Finnish Local and Regional Authorities, Helsinki 1999. Katupäällysteiden kehittäminen 1995– 1999. Loppuraportti (Research of street pavements 1995–1999. Final report). Association of Finnish Local and Regional Authorities, Helsinki 2000. Article specially written for NR&TR by Laura Apilo.

INSTITUTE OF TRANSPORT ECONOMICS (TØI), NORWAY

Implementation of road accident countermeasures – problems and possibilities Examples from Africa and Scandinavia

Assessing road safety work in five African countries, Assum (1998, p. vii) claims “There is no doubt that the main problem in Africa is the implementation of accident countermeasures rather than a shortage of countermeasures unique to African conditions”. Contrary to this statement, the position can be taken that road accident problems in Africa, or in developing countries in general, are of a different nature compared with those of the industrialized countries. Consequently, countermeasures with proven effect in industrialized countries cannot be expected to have the same effect in developing countries. However, if the first statement is true, the principal question is: What can be done to improve implementation of effective road accident countermeasures? Road accident situation

Table 1 briefly describes the road fatality situation in four African and two

PHOTO: HARALD AAS

In many African countries, the main problem regarding road safety is the implementation of effective road accident countermeasures rather than a shortage of countermeasures unique to African conditions. Comparing Africa and Scandinavia, the author claims that the problem is similar and the creation of a sense of urgency is an important condition for the implementation of countermeasures.

Scandinavian countries. What are the similarities and dissimilarities between Africa and Scandinavia as described in this table? Figures for Kenya (1995), Tanzania (1995) and Zimbabwe (1994) from Assum (1998). Figures for Mozambique and Norway (1997) are taken from Assum et al. (1999). Figures for Sweden are taken from National Road Administration 1999 and 2000. Dissimilarities

The dissimilarities are found in the risk of accident involvement, which can be operationalized as fatalities per 10,000 vehicles. This risk varies from 137 in Mo-

Although traffic accidents are a problem both in Scandinavia and in Africa, the countermeasures are not necessarily the same.

zambique to 1.2 in Norway and Sweden. The number of vehicles per 100 inhabitants also varies greatly, from 0.44 in Mozambique to more than 100 times as many in Scandinavia. What is not shown in Table 1 is the difference in the number of accident victims. In the African countries, pedestrians and public service vehicle passengers make up 70–80 per cent of the fatalities (Assum, 1998, p. 5) whereas in Scandinavia car occupants (drivers and passengers) make up almost 70 per cent of the fatalities (Official Statistics of Norway, 1998).

Kenya

Mozambique

Tanzania

Zimbabwe

Norway

Sweden

Fatalities

2617

960

1663

1274

303

580

per 10,000 vehicles

60.0

137

66.1

27.0

1.2

per 100,000 inhabitants

10.0

6.0

5.6

11.1

6.8

6.6

Vehicles per 100 inhabitants

1.7

0.44

0.8

4.1

Table 1. Road fatalities, total and by vehicles and inhabitants, and vehicles per 100 inhabitants. Four African and two Scandinavian countries. 1994–1999. 16

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

INSTITUTE OF TRANSPORT ECONOMICS (TØI), NORWAY

Similarities

The main similarity shown in Table 1 is that the public health problem, i.e. the number of fatalities per 100,000 inhabitants, is of the same magnitude, ranging from 5.6 in Tanzania to 11.1 in Zimbabwe. Norway and Sweden fall between these two African countries in this respect. Both African and Scandinavian countries have expressed the ambition of reducing the number of fatalities and serious injuries, despite a high increase in the number of vehicles in Africa and a high and still increasing number of motor vehicles in Scandinavia. Same problem – different situations

In both Africa and Scandinavia, the problem is to reduce to public health problems resulting from road accidents, although the situations are quite different. In the African countries, there are small but rapidly increasing numbers of vehicles; few countermeasures are implemented and the question is how to implement effective countermeasures. Low cost measures have a relatively effective accident-reducing

Speed limits Urban Rural BAC limit Mandatory seat belts

potential since implementation of measures has so far been somewhat limited. In Scandinavia, there are large numbers of vehicles, many countermeasures have been implemented, and the question is what more can be done. The measures known to be effective, such as speed enforcement and traffic engineering, still have a certain potential, but further implementation will lead to increased conflict with mobility and the cost will be very high. Table 2 shows that the African countries could benefit from lower speed limits in residential areas. Kenya, Mozambique and Tanzania need a clearly defined blood alcohol concentration (BAC) limit. Even if seat belts do not protect pedestrians and PSV passengers, mandatory seat belt installation should be introduced, since the number of private cars is increasing rapidly. In general, the main interests conflicting with road safety are mobility (in terms of speed and traffic volumes), personal freedom and the use of resources. These conflicts are the same in Africa and Scandinavia. Enforcement is a great problem

Kenya

Mozambique

Tanzania

Zimbabwe

Norway

Sweden

50 100 No?

50? No “Drunk”

50 100 0.08?

60 100 0.08; 0.15

30–50 90 0.05

30–50 110 0.02

Front seats

Yes

Table 2. Countermeasures implemented by country. 1990s. Question marks indicate that information on current rules and limits is difficult to obtain. Step

Africa

Scandinavia

Sense of urgency

Hardly

Possibly

Powerful guiding coalition

Possibly

Creating a vision

Yes

Communicating the vision

Possibly

Empowering others to act

Creating short-term benefits

Partly

Consolidating improvements and producing still more change

Far off

More is needed

Institutionalizing new approaches

Far off

Table 3. Kotter’s steps of transformation and major errors applied to road safety efforts in Africa and Scandinavia NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

in the African countries. The traffic police are in need of vehicles and communication equipment to carry out or increase enforcement. There is also a problem of the police accepting bribes that are considerably lower than fines, although the extent of bribery is unknown. In Zimbabwe, fines are set out in the Road Traffic Act. Due to inflation, fines no longer have a deterrent effect, but the introduction of changes in the Road Traffic Act takes a long time. Amending the Road Traffic Act seems to be a problem in most of the African countries studied. These countries also have a problem with approval of their Road Safety programmes. The Scandinavian countries face a situation where enforcement has been reduced for economic reasons. The introduction of automatic speed cameras and lower speed limits is a problem in Sweden owing to conflicts with personal integrity and mobility. Although the introduction of a lower BAC limit has been proposed in Norway, the amendment to the Road Traffic Act has been postponed several times due to legislative problems. Financing of road safety measures is a problem in Africa, especially for enforcement and traffic engineering measures. Several countries report that traffic-engineering measures are difficult to implement since road authorities put a higher priority on the resurfacing of roads. Even if the Scandinavian countries are much more affluent than the African countries, financing is still a problem, especially for enforcement and also for engineering measures. How to bring about change?

The question “What can be done to improve implementation of effective road accident countermeasures?” remains to be solved. J. P. Kotter’s (1995) article “Leading Change: Why Transformation Efforts Fail” will be applied in trying to answer this question. Kotter introduces eight steps in the process of transforming organizations, see Table 3. Although Kotter’s theory is designed for business companies, it may also provide various ideas about change in the public sector. Kotter states that successful change goes through a series of phases. It requires a considerable length of time and skipping steps only creates an illusion of speed and no results. 17

INSTITUTE OF TRANSPORT ECONOMICS (TØI), NORWAY

Scandinavian countries started their road safety efforts a long time ago. In the 1970s, road safety measures were implemented and the number of fatalities was considerably reduced. However, the number of motor vehicles in Norway in 1997 is more than twice that of 1974 (Official Statistics of Norway, 1981, 1998), creating a need for further road safety activities. However, in the African countries, with the possible exception of Zimbabwe, road safety work has hardly started, and the first step should consequently be emphasized in order to create motivation for change. Assum (1998) has described the main requirements for sustained road safety, Figure 1. In his model, political concern and funding are crucial to implementation and thus to accident reduction. Creating a sense of urgency is probably an important condition for establishing political concern. Conclusions

The implementation problems in the African countries are: - shortage of resources, - other serious problems that compete for resources, - conflicting interests, - lack of political concern, - lack of identification between decision makers and pedestrians/PSV passengers. The possibilities, on the other hand, are that: - effective countermeasures are known - potential for improvement is high - costs are relatively low

Awareness campaigns and publicity Cost/benefit analyses Donor pressure NGO and media Incentives

International funding Fuel levy Insurance levy Fees

Political concern

Accident reduction

Funding International assistance

Monitoring Evaluation Implementation

Programs

Demonstration projects

Know-how Incentives

Research

Figure 1. Main requirements for sustained road safety and ways of fulfilling them (Assum 1998)

The creation of a sense of urgency should be emphasized in both regions. Moreover, creating short-term benefits, i.e. showing that countermeasures are effective in reducing accidents, is important, especially in Africa but also in Scandinavia. In the event countermeasures known to be effective in industrialized countries prove ineffective in Africa, it will also be necessary to develop countermeasures tailored

to African problems. An important question, which has not been addressed in this article, is whether African countries should handle their problems in their own way, or whether other countries should try to help.

By Terje Assum, Senior Research Officer TØI

LITERATURE Assum, T. Road safety in Africa – Appraisal of Road Safety Initiatives in Five African Countries. Africa Region, World Bank, SSATP working paper No. 33. Washington DC, 1998 Assum, T. et al. Mozambique Road Safety Emergency Action Plan – final report. TØI report 461/1999. Oslo, Norway Kotter, J.P. Leading Change: Why Transformation Efforts Fail. Harvard Business Review March-April 1995

In Scandinavia, the problems are: - determining what more can be done, - high costs of further countermeasures, - conflicting interests, - lack of political concern.

Official Statistics of Norway. Road Traffic Accidents 1980. Statistics Norway. Oslo 1981

The possibilities are: - availability of relatively affluent resources, - handling of car occupants’ safety by the car industry, - development of new countermeasures.

Vägverket (SNRA). Information from Thomas Lekander, Borlänge, Sweden. February 21, 2000

Official Statistics of Norway. Road Traffic Accidents 1997. Statistics Norway. Oslo 1998 Vägverket (SNRA). Årsredovisning 98. Borlänge, Sweden, 1999

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

SWEDISH NATIONAL ROAD AND TRANSPORT RESEARCH INSTITUTE (VTI)

PHOTO: VTI

The VTI:s Wheel Tracking Test

The VTI’s WTT system is unique in a number of respects, principally its large size and capacity. It is originally developed at the Technical Research Centre of Finland, and is mainly used for rutting and water sensivity tests. Flow rutting of bituminous pavement layers has often been observed in recent years. This is particularly due to an increase in the maximum permitted axle load from 10 tons to 11.5 tons in 1993. Increased traffic volumes, coupled with the tendency to use higher tyre pressures and wide single tyres have also accelerated rutting. Normally, repeated load creep test is used for characterising the resistance to flow rutting. However, use of the creep test may be questionable in the case of new mixes, asphalt concrete reinforced with mesh and mixes whose resistance depends on the interlocking of aggregates. Therefore, a wheel tracking test that simulates asphalt materials under a rolling tyre is more accurate for characterising asphalt materials and validating other tests. A further aspect of interest is water sensitivity of bituminous pavements, in many cases a crucial factor for the service life of bituminous layers. Other water sensitivity test methods are criticised. The immersed wheel tracking test is regarded as

more realistic for studying the resistance to stripping and verifying the results from other methods. Technical specifications

The fully automated device comprises a servo-hydraulic testing system. Specially developed software is used for system control and data acquisition (profiles, temperature, load magnitude, number of wheel passes). Features: • Designed to test a single or multi-layer bituminous construction. • Size of slab specimen 700 x 500 x 40– 120 mm. Thickness is variable. More than one layer can be tested to simulate the overlay principle in the field, reinforcement structures and large stone mixes. • Wheel load can be varied between 7 and 25 kN (25 kN is comparable to 100 kN axle load with dual tyre configuration). • Truck or military aircraft tyres can be used, tyre size 6.00 R9 respectively Flight leader 24x7,7-14. Tyre pressure is 0.6–2.0 MPa depending on load and tyre type. • Wheel speed can be varied between 1 and 5 km/h. • The slab is installed in a climate chamber where the temperature can be varied between +5°C and 60°C. • The tempering medium can be air or water.

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

• Lateral wandering of wheel with up to seven positions is possible with a deviation of ± 3 cm from centreline. Resistance to flow rutting of some mixes is sensitive to the lateral drift of the loading wheel, as is the case in the field. • A laser profile measuring device with accuracy of ± 0.02 mm is used to measure up to five transverse profiles at predefined places and times. • The wheel can be loaded in one-way or two-way directions. • Three profile lines can be reviewed on the PC monitor: the first, the last and the last but one, as well as the progress of rutting as a function of the number of wheel passes. Further applications

The system has also been used for fatigue studies. Normally, roads that have deteriorated due to cracking are rehabilitated with a thin bituminous overlay. The cracks usually propagate rapidly through the new overlay. The resistance to crack propagation depends also on the type of mixture. Reinforcement of bituminous layers or the use of an interlayer can reduce the crack propagation time. This problem can be studied with the VTI’s system when testing at low temperatures. As a complement, an extra amplifier is used for recording strains. Strain gauges are usually attached at the bottom of the test slab. The wheel tracker has an extra amplifier and PC programme to control and/or record from devices. Up to eight channels can be used: in an EUproject (REFLEX- Reinforcement of Flexible Road Structures with Steel Fabrics to Prolong Service Life) they are used for data sampling of strains in the asphalt and reinforcement. The strains can be reviewed on the monitor as a function of time/number of applications. As in the programme for the flow rutting test, this system can also be given a preset start time and data volume to be stored. All data is saved for further analysis. Article specially written for NR&TR. by Safwat F. Said, safwat.said@vti.se 19

The Öresund Link The connection between Sweden and Denmark The Öresund Fixed Link between Sweden and Denmark will be inaugurated in June 2000. The Link, comprising a four-lane motorway and a dual-track railway, includes:

BILD: ØRESUNDSKONSORTIET

• An artificial peninsula which extends some 430 metres from the original shoreline. • A 3,510 m long tunnel between the artificial peninsula and an artificial island. • A 4,055 m long artificial island. • A toll station on the Swedish side. • The Öresund Bridge, which incorporates one high bridge and two approach bridges, has a total length of 7,845 metres. The main span of the high bridge is 490 metres. The total length of the Link is almost 16km.Ten thousand motor vehicles per day are expected to use the Link in its first year. Automatic weather stations will detect weather changes, enabling motorists to be warned via road signs of dangerous conditions such as ice or strong winds. Website: www.oresundskonsortiet.com

PHOTO: JAN KOFOD WINTHER

PHOTO: PIERRE MENS

PHOTO: JAN KOFOD WINTHER

Photos and illustraton: Øresundsbrokonsortiet

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

SWEDISH NATIONAL ROAD AND TRANSPORT RESEARCH INSTITUTE (VTI)

Computer simulations play an important role in the analysis of traffic systems. We present a new simulation model for the toll station at the Öresund Bridge, and show how it can be used to analyse the queues under various assumptions of service level and traffic load. Toll fees will finance the fixed Öresund link between Sweden and Denmark, which will be opened for traffic in summer 2000. The toll station at Lernacken, on the Swedish side of the bridge, will cover traffic from both directions. The procedure will be the following. Payment will be made on entering the toll station in manual, or automatic lanes, or in dynamic lanes where there is no need to stop. To use dynamic payment, cars must carry a small electronic device for identification and validating registration. Invalidated cars are led to a nearby manual lane. Figure 1 shows the toll station according to the model discussed in this article. In the figure, vehicles approach from the right and are then channelled between dynamic

payment on the leftmost or rightmost sides, and manual/ automatic payment in one of nine lanes in the middle part. For the design and operational use of the toll station, we are particularly interested in aspects of capacity and queuing. These include: (i) Average queue length and delay. (ii) Risk of very long queues; in particular, where there is a risk that the non-dynamic queue may block the entrance to dynamic payment. Drivers using dynamic payment would then be delayed, even if the dynamic payment system in itself has sufficient capacity. (iii) Sensitivity analysis; what would be the effect of an extra lane or shorter service times?

PHOTO: PIERRE MENS

Simulation model for the Öresund Link road toll station Simulation model

The computer model is based on discrete event simulation and is built on a wide set of assumptions and sub-models. Each vehicle is modelled on a micro level with properties, such as arrival and service times, method of payment and vehicle type, chosen by random numbers following given distributions. Queues are formed and vary in size due to stochastic variations in parameters of this type. In mathematical models, such as the simulation model presented here, it is a key issue to describe in detail the essential parts of “reality”, while other aspects can

Figure 1. The computer model of the toll station in Lernacken. The traffic comes from the right, in one of two lanes. The outermost lanes with green spots are for dynamic payment while the nine central lanes are for manual or automatic payment.

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

SWEDISH NATIONAL ROAD AND TRANSPORT RESEARCH INSTITUTE (VTI)

be ignored or described only briefly. There is always a critical balance between simplicity and accuracy. The art is to be detailed where necessary and to make rough simplifications whenever possible. For example, in the queue model, it is important to describe in detail the pattern and size of the arriving traffic flow, while the colour of the cars is less important. The built-in models describe the behaviour of individual vehicles or drivers. There are, for example, models for the time gaps between vehicles and the reaction and service times of individual drivers. Other model assumptions include the proportion of different vehicle types and the proportion of drivers using different payment methods. To provide an idea of how the built-in models work, we will now discuss two examples in more detail. The service time is the time it takes for a driver to pay, reckoned from the time when he reaches the cashier until the time when he leaves. There may be some waiting time between two vehicles, but this is not included in the service time. A preliminary service time is first drawn as a random number, typically from a normal distribution with given mean and standard deviation, although the type of distribution and parameters can be varied. It is then assumed that drivers with a longer queuing time have prepared themselves while waiting, and therefore are slightly quicker at the service point. To model this assumption, we decided that drivers with a queuing time longer than a certain value should have their preliminary time reduced by a few seconds. To this a minimum value is also applied, such that the resulting time may not fall below a certain level. From other toll stations, it is known that some drivers are very slow; with service times that in practice cannot be generated by a normal distribution with realistic parameters. We have therefore introduced a certain class of extreme drivers, for which the preliminary service times are taken from another distribution with much higher mean. When drivers are generated in the model and assigned properties, it is decided randomly whether they should belong to the class of extremes or not. Moreover, it is clear from empirical studies that the average service time decreases when the flow increases. When 22

2000 1800

1600

1400

1200

1000

800

600

400

200

1 0

0 2

Figure 2. Example of flow curve (left y-axis in vehicles/hour) and computed number of open lanes (staircase curve using the right y-axis). Here we have used the static method.

there are many vehicles behind the vehicle currently being served, the service seems to speed up. Very high flows may, on the other hand, increase the service time due to delays in the transaction systems. Another example of built-in models, aimed at reproducing reality, is the way we assume drivers choose lane. It is reasonable to say that an approaching driver takes a lane with the smallest number of vehicles queuing. To take account of the fact that certain lanes, for various reasons, are more popular than others, we modify this rule and assume that drivers try to minimise the product of queue length and a lane-specific weighting. In this way, a lane can be modelled as more popular simply by assigning it a low weighting. In the example shown in the table below, an approaching driver would choose lane 1, even though it contains a longer queue than the other lane. In total, there are more than 100 model parameters including, for example, the lane weightings mentioned above and parameters related to the generation of service times. Given the complete set of parameters, we also have to specify the traffic flow (vehicles per hour) as a constant or variable curve over the time period considered. The Lane

Weighting

Queue (vehicles)

1 2

0.8 1.1

4 3

Table. Example of lane selection. Following the rule using lane weightings, an approaching vehicle takes lane 1 even though lane 2 has a shorter queue.

number of lanes open simultaneously can then be specified or computed, as described in the next section. Number of open lanes

In the model, two different methods are implemented for estimating the required number of open lanes. The static method is used to compute the minimum number of lanes from the flow, the average service time, and a level of capacity usage specified by the user. For a varying flow curve, such as that shown in Figure 2, this procedure is repeated periodically. Using this method, we obtain the number of open lanes as a function of time before the actual simulation starts. There is also a dynamic method where the number of lanes open simultaneously is computed during the simulation. Starting from a certain number of open lanes, lanes are opened and closed according to a functional criterion based on the current capacity usage: Open a new lane if the queue exceeds n1 vehicles or n2 metres. Close a lane if the capacity usage during the time period has been lower than rmin. The two methods, static and dynamic computation, normally give similar results. A more significant deviation may be observed if the capacity usage is, or has been, very high. The static method may then close lanes even if there are long queues. The dynamic method is designed to focus on current capacity usage rather than the incoming traffic flow. Toll Queue Analysis (TQA)

The model described above has been implemented for Windows environment on

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

SWEDISH NATIONAL ROAD AND TRANSPORT RESEARCH INSTITUTE (VTI)

personal computers using the Borland Delphi programming language. The program, called TQA, handles all model parameters and the traffic flow, computes the required number of open lanes, performs simulation, and illustrates details in the simulation by animation. The programme estimates the mean, standard deviation and maximum value of • Queue length (vehicles and metres) • Queuing time • Proportion of drivers having to queue • Service time Each variable is estimated for the whole time period and given as a time series for the period considered. In the programme, we normally use standard statistical distributions, such as normal and exponential distributions, to describe stochastic variables. There is, however, a possibility to define new distribution functions based on empirical data. Given a set of data, for example observed service times, the program transforms the data to a user-defined distribution function that can be used in the same way as predefined standard distributions. Example

Let us now consider the example shown in Figure 2, and use the simulation model to estimate the expected queue length as a function of time. We use the standard parameter settings, which are not further described here, and run the TQA program. Simulation of the full 24-hour time period (more than 10,000 vehicles) takes about one minute on an ordinary PC. In practice, this is repeated a few times to obtain more accurate point estimates of the computed variables. Figure 3 shows the resulting curve for queue length in metres.

Queue length (meter) 100 90 80 70 60 50 40 30 20 10 0 2

Another example is the following: Assume that there is a constant flow of 800 vehicles per hour. What happens if the traffic, due to an accident, is blocked on the highway ten minutes ahead of the toll station? For a short period, this will result in a concentrated flow, resulting in temporary queues. How long does it take to restore the queues to normal lengths? First, we have to estimate how long it takes to restore the arriving traffic flow to normal level. Immediately after the road has been opened, the flow will be higher for a certain time. Let us assume that there is a minimum time gap of two seconds between successive vehicles. It follows that the maximum traffic flow is limited to 1800 vehicles per hour. During the tenminute blockage, about 140 vehicles arrive. To this we must also add vehicles arriving during the time period while the accumulated queue is being phased out. Let us assume that this takes ∆t seconds. The following relation, expressing the maximum flow, then applies: 140 + 800 · ∆t = 1800 ∆t

1800

1600

400

1400

350

1200

300

1000

250

800

200

600

150

400

100

200

1.5

2.0

2.5

3.0

3.5

4.0

It follows that ∆t = 0.14 hours, or about eight minutes. After this period, the traffic flow on the road is once again at a normal level. However, it will take much longer before the queues at the toll station are again normal. To model this case, we start with a constant flow of 800 vehicles/h, make it zero for ten minutes, increase it to 1800 vehicles/h for the next ∆t minutes, and finally restore the original level of 800 vehicles/h. This is shown in Figure 4. In the figure, we also show the simulated queuing time. It follows that the delay is increased for more than an hour due to the ten minutes of complete stoppage. This example shows how the simulation model can be used to analyse realistic scenarios. Another important class of problems is related to sensitivity analysis, e.g. what would be the effect of an additional lane, one-second shorter queuing time or other proportions between the different payment methods? It is for these types of questions the toll software has been developed and will be used.

Queuing time (seconds) 450

1.0

Article specially written by Pontus Matstoms, VTI for NR&TR.

0.5

Figure 3. Simulated queue length (meter) for the flow and service level shown in Figure 2.

2000

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Figure 4. The traffic flow is constantly 800 vehicles per hour. For a period of ten minutes the road is blocked ahead the toll station. The left graph shows this variation in flow and the right graph the response in queue time at the toll station. NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

SWEDISH NATIONAL ROAD AND TRANSPORT RESEARCH INSTITUTE (VTI)

Children with disabilities face major risks in traffic

There are no special rules stating how children with disabilities are to be protected during transportation by car or bus. Often, children’s disabilities make it impossible for them to use the seats and protective equipment provided. Instead, they are obliged to use their normal sitting aids, such as wheelchairs, which are designed for transportation at walking pace. They are not designed for protection against external violence; on the contrary, they collapse very easily in a collision. The best wheelchairs are made as light as possible and are thereby weak; the frame is of aluminium and the fabric in the seat is extremely thin. Risky transportation

Certain functional disabilities cause children to become extremely sensitive to external violence. Those who suffer from muscular dystrophy or bone brittleness, for example, will probably be very severely injured in a collision even if they are secured, since the functional disability reduces the capacity to distribute the impact forces over the body. “We know that children with disabilities face risks when they travel by car, school transportation or special transportation,” says VTI researcher Torbjörn Falkmer. Torbjörn Falkmer has carried out a study of children with disabilities and their families in cooperation with RBU, an association for children and teenagers with impaired mobility. Parents of children with disabilities have answered a questionnaire in order to survey the transport situ24

ation for children and answer questions as to how often, how far and by what method children are transported, etc. In addition, parents have stated how confident and satisfied they feel about the various transportation methods offered to children with disabilities. PHOTO: HÅKAN ALDÉN

Children, in particular those with disabilities, face a greater risk of being injured in traffic compared to adults. The reason is partly the child’s anatomy and partly the fact that aids used for transporting children with disabilities are seldom designed for protection in the event of a collision.

Unbelted children using school transport

The study showed that the children alternately ride in their parents’ car, school transport and special transport; most often, however, in their parents’ car. School transport often utilises an ordinary taxi or large school bus. Smaller buses are generally used for special transport, which means that if the bus is suited for 12 passengers or more, seat belts do not have to be used unless they are already installed, in which case they must be used. A carrier can thus transport unbelted children and still comply with the laws and regulations, which is a source of great anxiety for parents. The results obtained by Torbjörn Falkmer in the studies confirm his suspicions that it is both necessary and desirable to introduce rules and regulations for school transport and special transport when transporting children with disabilities. “What is most worrying is that there are no rules for special transport. It may well be an advantage for children with disabilities to travel by school transport despite the risks this involves, since they can then travel together with other children,” he points out. “At the same time, it’s difficult to understand why there are no rules requiring all children travelling by special transport to be secured. Those who use special transport do not travel for social reasons, but

because they have such serious impairments that they need assistance since they cannot travel by ordinary bus,” he continues. The study also showed that the drivers of special transports do not always know how they should secure wheelchairs and other aids. Instead of increasing the child’s safety, an incorrectly secured wheelchair may have the opposite effect and create a greater risk by tipping over if the vehicle suddenly brakes, for example. Although drivers do their best to help, the result is nevertheless unsatisfactory. We know that new rules have to be introduced and that drivers of special transport vehicles must be given training. Helping parents

In a crash involving a car with a wheelchair passenger, it is uncertain who is responsible if the wheelchair collapses or becomes dislodged and thereby contributes to the injuries. Is it the car manufacturer, the person who fastened the seat belt on the passenger, the person who installed the anchorages in the car, or the driver himself? In the case of children who are so short that there are no seat belts which fit them, since a normal seat belt would lie across the face, who is responsible if someone is killed in an accident? “If these matters are to be put in order,

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

SWEDISH NATIONAL ROAD AND TRANSPORT RESEARCH INSTITUTE (VTI)

included in the requirements for driving a taxi,” he states.

we must see that rules and regulations are made without putting parents in an impossible situation where they are forced to break the law. They want to drive their children, and this wish must be respected. There is a risk that children will suffer even more if the rules are so tough that parents can’t transport them. We have to find some sort of balance,” says Torbjörn Falkmer.

Further studies

Every year, about 100,000 children are born in Sweden, and of these approximately 600 have impaired mobility. Despite the fact that this group is relatively large, there have been no recent studies until now which deal with their transport situation. On the other hand, technical aids have been developed, although these are unsuitable for use in a car or bus. With the new European standard CE marking, the possibilities of adapting the child’s normal aids, such as a wheelchair, will be reduced considerably. If a wheelchair is CE-marked, this means that it is the manufacturer who is responsible for the product. If a wheelchair is CE-marked and then adapted, the manufacturer is no longer responsible, but instead the company who did the adapting. Since the technical aids centres, which often carry out such adaptations, seldom take responsibility for these, it will be increasingly difficult for families with disabled children to obtain help with adaptation. “Parents may then find themselves in a position where their child has been given an excellent wheelchair, but can’t use it in the car. In this case, it will be necessary to have an extra seat which can only be used in a car, and to transfer the child to it each time. There is a risk that excessive demands will be set on safety in transporting children, at the same time as problems are created for their parents, so that the children’s transport possibilities are reduced,” says Torbjörn Falkmer. Very few children use a seat belt

The studies also show clearly that far from every child uses a correctly fastened seat belt when travelling by car. Furthermore, there are also children who are secured with a seat belt, but the wheelchair they sit in is not secured. There are also those who travel without a seat belt in a secured

PHOTO: VTI

Recent studies

Torbjörn Falkmer bildtext

wheelchair. All these variants are common, and would have very serious consequences in the event of a collision. “A plastic crate lying loosely on the rear seat can kill a person in a collision at a relatively modest speed if it is thrown forward, and even small children weigh a great deal more than a crate. An electric wheelchair can weigh more than 100 kilos,” says Torbjörn Falkmer. Education and regulations

According to the Vision Zero*, the traffic system must be designed on the basis of the weakest and most vulnerable persons in traffic. Torbjörn Falkmer claims that this will be impossible unless detailed rules are drawn up for the transport of children with disabilities. “Something must be done about the children’s transport situation if the commitments in the Vision Zero are to be met. Besides travelling without protection, the children are also not secured,” he points out. We can never reach a zero level in traffic fatalities unless tougher rules are introduced.” Torbjörn Falkmer hopes that some type of certification will be introduced requiring every person wishing to drive a special transport vehicle to attend a special course on how to secure a wheelchair correctly and how to the child should be belted. “Driving a special transport vehicle is not the same thing as driving a goods vehicle. Even though drivers of vehicles with hazardous goods are given special training, drivers of special transport vehicles only have to have a taxi licence. I think this is very strange. It would have been better if this type of education had been

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

Next year, Torbjörn Falkmer will be carrying out a series of case studies on a number of children with severe transport problems. Total solutions will then be designed which must perform satisfactorily both inside the vehicle and in collision tests to ensure safety. The collision tests will set high demands on the crash test dummies, since children with disabilities do not behave in the same way as other children in a collision. The second study planned by Torbjörn Falkmer will involve children with autism. Since behavioural problems are common in this group, functional impairments can lead to serious consequences, for example, in the use of safety equipment when travelling by car or bus. During the spring, an application will be made for a grant to survey the transport situation of this group together with Föreningen Autism (Society for Autism). This spring will also see the completion of a project to study driving education for car drivers with perceptual and cognitive functional disabilities. The results will be reported at the VTI on 24 May. * Vision Zero – the national basis for Swedish road safety. An image of a desirable future society in which nobody would be killed or seriously injured in road traffic.

Title:

A survey of the transport situation for children with functional disabilities. Author: Torbjörn Falkmer Series: VTI rapport 448 Language: English Title:

A survey of the transport situation for children with functional disabilities. A pilot study of weekday journeys for children with extensive mobility impairments. Authors: Torbjörn Falkmer and Åsa Fasth Series: VTI notat 71-1999 Language: English

Annotated reports from the Danish Road Directorate (DRD)

Road Safety Audit World Road Congress in Kuala Lumpur, October 1999

Road Safety Audit is a systematic procedure which incorporates traffic safety knowledge into the road planning and design process with the purpose of preventing traffic accidents. The concept of Road Traffic Audit used in different countries, as well as their level of experience, differs considerably. The World Road Association (PIARC) Committee 13 on Road Safety has focused on the subject of Road Safety Audits.

Information on current practice and experience in different member states has been collected, analysed and discussed by the C13-WG3 members: Lene Herrsted, Denmark WG3, Chairman) Michel Labrousse, France Hubert Treve, France Peter Vasi, Hungary Ian Appleton, New Zealand Andreas Gantenbein, Switzerland

The results of this work have been summarised in Part I. The content of Part II is a summary of Danish experience. Parts I and II have been presented at the C13 session on Road Safety Audit at the World Road Congress in Kuala Lumpur in October 1999. Author: Lene Herrsted Series: Note 67 Language: English

Concrete bridges suffering from alkali silica reactions 15 years experience with surface coating

Up to the late 1970s, concrete structures in Denmark were sometimes built with alkali silica reactive fine aggregate. This was before systematic precautions were taken to avoid this problem. Therefore, many bridge structures in Denmark are currently suffering from deleterious alkali silica reactions that have caused extensive cracking. This damage does not always directly affect the loadbearing capacity of the structures since the compressive strength of the concrete is often sufficient. The problems

arise when secondary causes of damage are involved. Frost action disintegrates the concrete, while chloride from de-icing salts, for example, damages the reinforcement. De-icing salts also introduce alkali to the concrete so that there is an unlimited alkali supply to all the reactive flint in the concrete. To avoid secondary damage, surface protection of the concrete is a possibility provided that the surface protection does not harm the concrete and at the same time is able to bridge the cracks. This report

presents 15 years of experience in using this measure against such secondary damage. The report shows photos of selected details on the bridges taken from the period before the surface protection was applied in 1983 and up to 1998 . Author:

J.M. Frederiksen, AEC Consulting Engineers Ltd Series: Report No. 188 Language: Danish with English abstract

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

Annotated reports from VTT, Communities and Infrastructure, Finland

Accident costing using value transfers New unit costs for personal injuries in Finland

The study deals with valuation of economic losses resulting from personal injuries in road traffic accidents. Valuation of human welfare losses is examined in particular. The study presents an analysis of valuation methodologies currently used in Finland and some other countries for estimating the unit values of personal injuries. The theoretically correct method for valuing human welfare losses in economic terms is presented, and recommendations for a new practice in Finland are made accordingly. The individual willingnessto-pay method is proposed to be adopted for valuing the changes in accident risk subjectively. This method will produce theoretically consistent risk values for representing human losses of traffic accidents. The theoretical foundation of the methodology also highlights how econom-

ics considers the welfare of living in risky environments. A change in valuation methodology immediately calls for a revision of currently used unit values in Finnish highway economics. Therefore the study examines the whole range of existing value estimates and their components. However, no empirical cost inventories or valuation surveys are carried out. The new unit costs for personal injuries are based on both earlier cost inventories and values transferred from Sweden. The applicability of such value transfer is discussed theoretically. Finally, the study presents a proposal on unit costs for personal injuries recommended to be applied in project appraisals and socio-economic costing of transport in Finland. The report is available in its entirety,

free of charge, in pdf format on the web at: http://www.inf.vtt.fi/pdf/publications/ 1999/P396.pdf

Author: Juha Tervonen Series: VTT Publications 396 Language: English

Traffic safety at grade-separated junctions The traffic safety of 95 typical grade-separated junctions on a basic road network in Finland was studied by accident analysis. Accident data included police reported accidents from 1990 to 1997. The aim of the study was to determine the exact location of accidents at the junction and to compare the traffic safety of grade-separated junctions with that of level junctions. Traffic safety was measured by the number of accidents and by accident rates. A total of 591 accidents, excluding animal accidents, occurred at the studied grade-separated junctions. Accident data included 167 injury accidents and 424 damage only accidents. Sixteen of the accidents were fatal. The accident rate of all accidents on single carriageway roads was 0.30 and that of injury accidents 0.07 accidents per million incoming vehicles. On two carriageway roads the accident rate of all accidents was 0.39 and that of injury accidents 0.08 accidents per million incoming vehicles. The most typical accident at gradeseparated junctions was an accident with

Most common accident types when turning left

Most common accident types when turning right main road

ramp

main road

24% of accidents of turning vehicles

14% of accidents of turning vehicles

a turning vehicle (32%, figure). Other typical accident types were single accident (20%), overtaking accident (13%), rearend accident (8%) and accidents with an oncoming vehicle (5%). The percentage of animal accidents was 6%. The accident data included many injury accidents with one vehicle turning left and the other coming from the crossing direction (14%), and single accidents. The accident risk of both all and injury accidents was lower at grade-separated junctions on the basic road network than at level junctions. The grade-separated

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

main road 15% of accidents of turning vehicles

ramp 13% of accidents of turning vehicles

junctions on single carriageway roads had a lower accident rate than the level junctions. On two carriageway roads the accident risk of all accidents was near to that of three-legged level junctions. The accident rate of signalled junctions was higher than that of grade-separated junctions.

Author: Kirsi Pajunen Series: Finnra Reports 21/1999 Language: Finnish with English abstract

Annotated reports from the Norwegian Public Roads Administration

Cold bitumen stabilised bases The Norwegian Road Research Laboratory has recently published an English version of the guidelines on “Cold bitumen stabilised bases”. The guidelines are part of those supplementing “The Norwegian Design Manual” on various subjects. They describe mix design and production methods, as well as laying and compaction

of cold bitumen stabilised base materials. The main emphasis is on foam mixes and emulsion gravel, but the guidelines also deal with cold-in-place recycling. Author: Jostein Myre Series: Handbook 198E Language: English

Safety measures against avalanches – design and challenges The intention of this report is to bring the aesthetic design of safety measures against avalanches into focus. The aim is to stimulate debate as well as to establish a basis for further research into the design of these safety measures, thereby providing a basis for creating aesthetically attractive and well-designed structures. Comments and evaluations have been made regarding a number of examples presented in the re-

port. The report was produced after making visits to four counties/countries. The types of structure covered include avalanche sheds and tunnels, wide trenches, safety nets and supporting structures. Author: Inge Dahlman Series: Misa report 99/10 Language: Norwegian

Rock engineering, concrete and road technology Through necessity, Norwegian contractors and engineers have had to develop new technologies and innovative solutions involving advanced rock engineering and concrete structures. These have been vital to the construction both of Norway’s sophisticated road infrastructure and its renowned offshore platforms and underground hydropower plants. Today, Norwegian companies are exporting state-ofthe art equipment, technology and expertise around the world. This pamphlet

provides an overview of rock engineering and the application of concrete and road technology in Norway, together with several of the innovative companies and the broad range of products and services they have to offer.

Series:

Norway Exports, Vol. 99, No. 10, 1999 Language: English

IDV – Measurement and analysis of structures The objective of the project was to investigate the real behaviour of structures. This can be done by performing design verification of the static and dynamic behaviour of a structure. Verification of condition and service life is also possible. The activities involved are instrumentation, field testing, analysis and comparison between measured and calculated values. Instrumentation is selected on the basis of the required verification and the 28

need for reliable results. The IDV method (Instrumentation, Documentation and Verification) has been used to verify the design assumptions applying to several large bridges, such as the Helgeland, Skarnsundet and Støvset Bridges. The project includes further development of the IDV method, training of NPRA personnel and monitoring of instrumented structures. A manual describing the IDV method and its use was published in 1999.

Authors: Ian Markey et al. Series: Handbook 212 Language: Norwegian

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

Annotated reports from the Institute of Transport Economics (TØI), Norway

Traffic safety of the elderly Among elderly persons in Norway, there are fewer traffic casualties, but more fatalities, per capita than among middleaged persons. The lower casualty rate is explained by lower exposure, and the higher fatality rate by the frailty of elderly people. The injury risk per kilometre travelled increases with age for all road user categories. Although the risk among elderly pedestrians has decreased during the last 20 years, pedestrians still make up the largest group of injured persons

aged 80 or more. The share of elderly drivers involved in accidents and/or being injured is expected to increase owing to a rise in the proportion of license holders among the elderly. On the basis of a comprehensive literature survey, the report discusses age-related changes in sensory, cognitive, and motor functions that may explain the increased risk for the elderly, and discusses possible safety measures. Further knowledge about the exposure of elderly road users under different traffic

conditions is needed. An interesting question is the extent to which they compensate for limited capacity. Authors: Fridulv Sagberg, Alf Glad Series: TØI report 440/1999 Language: Norwegian with English summary

Improving road safety in Norway The report contains an analysis of the consequences of five alternative strategies for the implementation of road safety measures in Norway. It is possible to achieve a drastic reduction in the number of fatalities and injuries in road accidents. However, a continuation of the current use of road safety measures will not lead to any

improvement in road safety. The analyses show that it is possible to reduce the number of fatalities and injuries without spending more on road safety than at present. By implementing measures whose benefits are greater than their costs, the number of fatalities can be reduced by about 180 per year and the number of in-

jured road users by about 4,300 per year. The current numbers are about 310 fatalities and 12,000 injured road users per year. Author: Rune Elvik Series: TØI report 446/1999 Language: Norwegian with English summary

Zero traffic fatalities – from vision to implementation The success of “Vision Zero” will only be possible through the implementation of various radical measures involving the road infrastructure, high speeds in sparsely populated areas and residential areas, urban surroundings and the use of relatively new technology. Implementation is discussed in relation to existing knowledge, goal conflicts, organisational matters, public support, possible networks and the existence of negotiable solutions.

Synergy, simple organisation, public awareness and possible compromises are fundamental for the implementation of necessary measures. Author:

Trygve Solheim Series: TØI report 448/ 1999 Language: Norwegian with English summary

Forecasting models for air traffic This working report presents different air traffic forecasting models for Norway. The models forecast the number of travellers at 17 chosen links in the conventional Norwegian network. The passengers are divided into two marked segments; business and leisure. Properties and results from models developed in this working report are com-

pared to existing models developed by the Institute of Transport Economics. The existing models are PHOENIX and “The National Model System for Private Travel”. The working report also presents a reestimation of PHOENIX, including a division of this model into business and leisure travellers. The working report includes a discus-

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

sion of the underlying data and the research on which the models are based. Author: Series:

Geir Thomas Knutheim TØI working report 1136/1999 Language: Norwegian

Annotated reports from the Institute of Transport Economics (TØI), Norway

Competition between transport modes and intermodal transport in the Norwegian freight industry

Everyday travel and use of information technology at home

The aim of this report has been to analyse the freight transport market in Norway, answering the question of whether it is possible to raise the level of intermodal transport solutions in Norway. The analysis is mainly based on national statistics. Road transport accounts for almost all freight on distances less than 100 km, but has been increasing also on longer distances, in particular for general cargo. There has been a transfer of low-value general cargo and high-value bulk from sea and rail to road. Rail is competitive with road transport primarily for carriage of general cargo on its main routes. We have shown that the road freight price is 6% lower on routes with parallel rail transport, while no such differences can be shown for alternative sea routes. A rough estimate indicates that about 25% of goods carried 100 km or

The relation between mobility and use of stationary communication has been studied on the basis of the National Personal Travel Survey 1997/98 and a postal survey of the use of information and communication technology at home. From these results, we cannot see any substitutional effects of the use of stationary technology at home on the use of mobile technology. Access to and use of information technology do not seem to have a significant impact on travel activities in everyday life. Stationary communication seems to be a supplement to activities based on mobile technology. For people who work more than “normal” weekly working hours, stationary technology seems to offer greater flexibility in regard to workplace location, but does not necessarily reduce their travel activity. Spatial flexibility also provides temporal flexibility, which means that work trips and other trips can be more widely dispersed during the day compared to the present situation. A positive consequence is a possible reduction in rush-hour traffic, while a negative consequence is that it is more difficult to offer satisfactory public transport service when travel needs are more widely spread over time.

longer are cross-loaded between two different transport modes in a single transport chain. Authors:

Inger Beate Hovi, Tron Even Skyberg, Knut Bøe Series: TØI report 447/1999 Language: Norwegian with English summary

International trends within freight transport The Norwegian transport and logistics market is heavily influenced by international factors. This is partly due to extensive trade with other countries, and also to co-operation with the European Union contributing to a stronger integration of the European transport market. This report contains an overview of the main international trends in freight transport. Globalisation affects transport distance and cargo mix, as well as logistics. A focus on sustainable growth has initiated a process aimed at creating optimal incentives for the choice of transport mode. From a supply-chain-management point of view, expensive solutions in one element of the process may be optimal if they

lead to overall cost reductions. The demand for transport may thus be somewhat insensitive to relative price differences between the modes. In order to depart from the current trend path, intermodal transport must be made more attractive. This may be achieved through efficient terminals, technical and organisational crossborder harmonisation, and information and communication systems.

Author: Randi Hjorthol Series: TØI report 454/1999 Language: English

Author: Series:

Tron Even Skyberg TØI working report 1144/1999 Language: Norwegian with English summary

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

Annotated reports from the Swedish National Road and Transport Research Institute

In response to the lively debate into ways of addressing the high level of involvement of young drivers in road accidents, the Stora Holm Driver Training Centre has invested resources in a training concept known as “Insight”. This comprises six different stations, the purposes of which are to raise pupils’ awareness of the benefit to be gained from using safety equipment in cars and to get them to appreciate the importance of speed and large safety distances in order to be able to drive safely in traffic. The stations include the head from a crash test dummy, a crash sledge, a rollover simulator and three different video films. Pupils are also shown the vehicles involved in the crashes portrayed in two of the films. A discussion also takes place at each station between the pupils and the instructor. The study was based on personal interviews with individual pupils and the obtained answers to the following questions were evaluated: • How was “Insight” experienced by those pupils who visited the facility? How did

PHOTO: STORA HOLMS TRAFIKÖVNINGSPLATS

The driver training concept “The Insight” – an evaluation

Roll-over simulator.

they perceive the message? What did they learn? Did it produce any effect of any aspect of their driving? • Where the practical driving sessions on the skid-pan and the skid training was a whole perceived any differently as a result of the pupils having visited “Insight” and, if so, in what ways? • Does a visit to the “Insight” facility influence pupils’ attitude towards seat belts, the distance to the vehicle in front, speed and road conditions? The results of the evaluation indicate among other things that a visit to “Insight”

has positive effects on pupils’ attitude towards and their use of seat belts. However, the visit did not cause these pupils to think any differently about the distance to the vehicle in front, speed or road conditions, compared with pupils who did not visit “Insight”. If the message is clear, and if the stations are used correctly, safety facilities such as “Insight” can be regarded as having a good potential for increasing pupils’ awareness of the benefit gained from using the safety equipment fitted in cars. Authors:

Anders Nyberg and Inger Engström Series: VTI rapport 443 Language: Swedish with English summary

Winter cycling – The importance of road standard for choice of mode Half of all the car trips made are shorter than five kilometres. From an environmental perspective it is especially important to reduce the number of short car trips since they are responsible for a relative large amount of the emissions caused by traffic. Choice of transport mode is affected by attitudes, socio-economic and demographic factors and by a variety of external factors. But how important is the road maintenance and operational standards of cycle tracks in choice of mode? The purpose of this study was to investigate how important the road maintenance and operational standards of cycle tracks are in choice of mode. A total of 433 employees at four major companies answered a questionnaire concerning their choice of mode for travel to work and the winter maintenance of cycle tracks.

A surprisingly large proportion of the car trips to work are shorter than 3 kilometres (just over 25% in the summer period, and approximately 40% during the winter period). Some of these trips cannot be made by bicycle instead since they involve people who require their car for work related travel or for transport of goods, etc. Other factors which are generally considered to play an important role in choice of mode are travel time, cost, temperature, precipitation, road conditions, exercise, access to parking facilities, etc. Winter cyclists value exercise to a much greater degree than others do. Factors that are also of greater importance to winter cyclists are cost and environmental concern. Travel time, temperature, precipitation and darkness is not so important for winter cyclist.

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000

General opinion regarding the winter maintenance of cycle ways is that it needs improving – as many as 57% are of this opinion. If winter maintenance was improved, 30% believe they would cycle more often and 12% they would cycle much more often. All potential winter cyclists are probably to be found in the “only summer cyclists” group. Approximately 67% of these believe that improved winter maintenance would persuade them to cycle more often, 15% much more often and 52% some more.

Author: Anna Bergström Series: VTI meddelande 861 Language: Swedish with English summary

Questions concerning the content of the articles, or orders for the publications referred to, should be directed to the publishing institution, see addresses below. REQUESTS FOR BACK ISSUES, AND NOTIFICATION OF ADDRESS CHANGES: Readers outside the Nordic countries: see Swedish address. Readers in the Nordic countries: see addresses below. Web site: www.vti.se/nordic

Denmark Helen Hasz-Singh Danish Road Institute P.O. Box 235 DK-4000 Roskilde Phone: + 45 46 30 70 00 Fax: + 45 46 30 71 05 E-mail: hhz@vd.dk

Norway Harald Aas Institute of Transport Economics (TØI) P.O. Box 6110 Etterstad N-0602 Oslo Phone: + 47 22 57 38 00 Fax: + 47 22 57 02 90 Order phone: + 47 22 57 39 13 E-mail: harald.aas@toi.no 32

Finland

Iceland

Kari Mäkelä VTT, Communities and Infrastructure P.O. Box 1901 FIN-02044 VTT Phone: + 358 9 45 64 586 Fax: + 358 9 46 41 74 E-mail: kari.s.makela@vtt.fi

Hreinn Haraldsson Public Roads Administration Borgartún 7 IS-105 Reykjavik Phone: + 354 563 1400 Fax: + 354 562 2332 E-mail: hrh@vegag.is

Norway

Sweden

Helge Holte Norwegian Public Roads Administration P.O. Box 8142 Dep. N-0033 Oslo Phone: + 47 22 07 39 00 Fax: + 47 22 07 34 44 E-mail: helge.holte@vegvesen.no

Sigvard Tim Swedish National Road and Transport Research Institute (VTI) SE-581 95 Linköping Phone: + 46 13 20 40 00 Fax: + 46 13 14 14 36 Order phone: + 46 13 20 42 24 E-mail: sigvard.tim@vti.se

NORDIC ROAD & TRANSPORT RESEARCH NO. 1 · 2000