Traffic impact assessment by Riza Atiq Rahmat

Traffic Study: Traffic Impact Assessment A brief note for Urban Transport Course By Riza Atiq Rahmat Universiti Kebangsaan Malaysia

Traffic Study – Traffic Impact Assessment 

All development will generate traffic into current or future transport facilities



All big development will generate internal traffic

TIA will answer the question of:  What will the effect of a development to the surrounding transport facilities  What is the magnitude additional traffic due to the development to the existing traffic  How will the additional traffic effect the current traffic 

What is the proposal to alleviate or minimise the impact

High density development will generate high volume of traffic 1

Developer

Architect / town planner

Local Authority

Instruction by the local authority to execute TIA

Appointment of a transport engineer

Discussion to determine the scope, study area and study methodology

Collate existing data and information

Traffic survey

Analyses:  Trip generation  Modal split  Trip distribution  Trip assignment  Analyses of LOS (Level of service)  Problem evaluation  Proposal to alleviate or reduce the identified problems

Review the original lay-out plan and propose any improvement to the client and land use

Final Report

TIA Content 1. Existing Situation  Existing government transport policies for the development area  Structure plan and local plan prepared by the Local Authority  Existing traffic and public transport facilities 1200

Traffic Volume (PCU/Hr

1000

800

600

400

200

0 6-7

7-8

8-9

9-10 10-11 11-12 12-13 13-14 14-15 15-16 16-17 17-18 18-19 19-20 20-21 21-22 Masa Menuju P/Bandar Dari P/Bandar

16 hours traffic count

65 34 54 28 52 62

42 59 59 45

62 75

Direction

Traffic Volume

Green Time (s)

Lane

Capacity

V/C ratio

South bound - straight - Right turn - Left turn

658 345 542

32 32 59

2 1 1

980 490 903

0.67 0.70 0.60

North bound - straight - Right turn - Left turn

758 451 621

43 43 61

2 1 1

1317 658 934

0.58 0.68 0.66

West bound - straight - Right turn - Left turn

598 423 597

27 27 70

2 1 1

827 413 1072

0.72 1.02 0.56

East bound - straight - Right turn - Left turn

527 287 621

18 18 50

2 1 1

551 275 766

0.96 1.04 0.81

 Road safety record  Pedestrian facilities  Identify all planned transport facilities in the vicinity of the development  Identify all other developments in the vicinity of the development and quantify the combine impact to the external traffic  Identify all existing public transport facilities and the impact of the development to the facilities  Identify potential traffic problem in the development

2. Analyses Trip Generation Land use Office

Attraction per 100 sq.m floor area (morning) 3.7 person / hr

Production per 100 sq.m floor area (afternoon) 4.05 person / hr

Hospital

1.52 person / hr

1.32 person / hr

Shopping Centre

0.45 person / hr

0.95 person / hr

Primary school

2.5 person / hr

High School

2.5 person / hr

College / University

2.0 person / hr

1.8 person / hr

Land use Apartment

Production per unit (morning) 2.11 person / hr

Attraction per unit (afternoon) 1.79 person / hr

Condominium

2.05 person / hr

1.73 person / hr

Flat / low cost house

2.51 person / hr

2.10 person / hr

Single story link house

2.21 person / hr

1.81 person / hr

Double story link house

2.52 person / hr

2.15 person / hr

Semi detached house

2.55 person / hr

2.17 person / hr

Bungalow house

2.65 person / hr

2.25 person / hr

Example

Morning Land use Flat Single story link house Double story link house Condominium Total

Residential unit

Production rate Morning production

845 725

2.51 2.21

2121 1602

934

2.52

2354

837

2.05

1716 7793

Petang Land use Flat Single story link house Double story link house Condominium Total

Residential Production unit rate

Morning production

845 725

2.1 1.81

1775 1312

934

2.15

2008

837

1.73

1448 6543

Trip Distribution Gravity Model

Pi Aj Tij = Ki Kj Tij Where

Tij = Trip from zone i to zone j Pi = Production of zone i Aj = Attraction of zone j Tij = Travel time or travel cost between zone i and zone j  = Parameter to be calibrated. In Klang Valley,  = 2.05 for morning and afternoon peaks.

1 Ki =  Kj Aj / Tij j

1 Kj =  Ki Pi / Tij i

Aj / Tij Production Constraint Model:

Tij = Pi  Aj / Tij j

Pi / Tij Attraction Constrain Model:

Tij = Aj  Pi / Tij i

Example

Proposed Development

Trip Generation Land use

QTY

Rates

Flat

205

2.51

Link house

431

2.21

Semi-D

125

2.55

2.65

Bungalow

Production

Total

515 953 319 138

1924

Trip Distribution Destination

Travel Time (min)

Estimated attraction

Aj / Tij2.05 Distribution

Trip Distribution

Ipoh

92000

62.871

0.271

522

Batu Gajah

16500

15.466

0.067

128

Gopeng

17200 153.295

0.662

1273

Aj / Tij2.05 231.632

1.000

1924

 =

Notes: Distribution = (Aj / Tij2.05 ) / ( Aj / Tij2.05)

Modal Split (Modal Choice) Influencing factors Car ownership Household Income Distance to the transport facilities Travel Time Travel Cost Car park availability

     

Peak Hour Modal Split in Kuala Lumpur Land use

Bus %

Car / van / jeep %

27.6

57.4

15.0

Government Office Company Office

48.0

45.6

6.4

Bank

49.9

45.0

5.1

Hotel

35.9

60.1

4.0

54.3

40.7

5.0

Shopping Centre Bungalow house

12.1

84.0

3.9

Semi-D house

16.2

79.4

4.4

Link House

42.1

48.5

9.4

Condominium

13.7

85.1

1.2

Apartment

39.9

45.0

15.1

Flat

49.5

28.3

21.7

Motor cycle %

(Source JKAL, DBKL Annual Report, 1991)

Average Passenger (including driver) in Kuala Lumpur. Land Use

Car / Van / Jeep

M / Cycle

Bus (big)

Bus (Mini)

Office

1.55

1.25

Hotel

1.55

1.25

*40

Shopping Centre Houses

2.14

1.30

2.05

1.38

(Source: JKAL, DBKL Annual Report, 1991)

Example A local authority has approved a proposed development of a housing estate. It consists of 1250 link houses, 155 semi-D houses, 78 bungalow houses, 390 units condominiums, 820 units apartments and 970 units of flats. Calculate both inbound and outbound traffic flows during morning peak hours.

Land use Unit Prod Produ Modal Split Person trip Number of cion uctio Vehicles n Bus car M/C Bus car M/C Bus car M/C rate Link house 1250 2.21 2763 42.1 48.5 9.4 1163 134 260 16 654 188 % % % 0 Semi-D 155 2.55 395 16.2 79.4 4.4 64 314 17 1 153 13 % % % Bungalow 78 2.65 207 12.1 84.0 3.9 25 174 8 1 85 6 % % % Condo 390 2.05 800 13.7 85.1 1.2 110 680 10 1 332 7 % % % Apartment 820 2.11 1730 39.9 45.0 15.1 690 779 261 9 380 189 % % % Flat 970 2.51 2435 49.5 28.3 21.7 1205 689 528 16 336 383 % % % total 44 1939 786

Trip Assignment Assigning O-D trips to the transport network

to Ipoh

To PLUS Hâ&#x20AC;&#x2122;way 981 ukp/j

247 ukp/j 759 ukp/j Proposed Development

365 ukp/j to Batu Gajah

603 ukp/j 61 ukp/j 1021 ukp/j

to Gopeng

Assumption: Traffic growth 4.1% Base year: 2000

2004 To Ipoh

To PLUS Hâ&#x20AC;&#x2122;way

247 ukp/j Proposed Development

790 ukp/j

380 ukp/j 603 ukp/j

To Batu Gajah 61 ukp/j 1063 ukp/j

to Gopeng

To Ipoh

to PLUS Hâ&#x20AC;&#x2122;way

1690 ukp/j

Proposed development 1443 ukp/j

1303 ukp/j

to Batu Gajah

to Gopeng

3. Impact to the Road Network

Level-Of-Service (LOS) = Flow/Capacity (or V/C) V/C < 0.9 OK

V/C > 1.0 (LOS = F)

V/C < 0.3 (LOS = A)

4. Road Safety Safe to the residences Safe to the visitors

5. Internal Lay-out

6. Parking Space

Malaysia: 1 cps / 500 sq.ft floor area or 1.25 / residential unit

7. Public Transport

8. Pedestrian, bicycle and disable facilities