Resident Risk In Oxford City
WELCOME Welcome to the SIGNPOST SERIES , a suite of reports to support professionals working in Road Safety. Designed by Road Safety Analysis, these profiles provide an authoritative overview of performance that can assist in directing investment and effort to reduce casualties on the roads. For more information on other services offered by Road Safety Analysis, please visit www.roadsafetyanalysis.co.uk
CONTENTS Welcome .................................................................................................................................................................. 2 Contents ................................................................................................................................................................... 2 Introduction ............................................................................................................................................................. 3 Quality of postcode data...................................................................................................................................... 3 Overview of Oxford City ........................................................................................................................................... 4 Overall resident risk ................................................................................................................................................. 4 Resident casualties of any severity ...................................................................................................................... 4 Resident killed or seriously injured (KSI) casualties ............................................................................................. 4 Progress in reducing resident risk ........................................................................................................................ 4 Resident risk by age group ....................................................................................................................................... 6 Resident child casualties ...................................................................................................................................... 6 Resident young adult casualties .......................................................................................................................... 6 Resident adult casualties ..................................................................................................................................... 6 Resident senior casualties.................................................................................................................................... 7 Resident risk for vulnerable road user groups ......................................................................................................... 8 Resident pedestrian casualties ............................................................................................................................ 8 Resident pedal cycle user casualties .................................................................................................................... 8 Resident motorcycle user casualties.................................................................................................................... 8 Large motorcycle user casualties ..................................................................................................................... 8 Small motorcycle user casualties ..................................................................................................................... 9 Resident young adult drivers ............................................................................................................................... 9 Appendix ................................................................................................................................................................ 10 Data sources....................................................................................................................................................... 10 Correction for missing postcode data ................................................................................................................ 10
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SIGNPOSTS
2012: RISK OXFORD CITY
IN ROAD SAFETY
RESIDENT CASUALTIES FOR
OF
By Road Safety Analysis
INTRODUCTION The SIGNPOST SERIES are road safety profile documents which provide comprehensive insight into risk faced by local communities. Each profile examines either road risk on the network of a specific highway authority, or risk experienced by the residents of a particular local authority district area. This profile examines risk to residents in Oxford City. All crash, vehicle, driver and casualty information in this document is derived from national STATS19 data for a six year period from 2006 to 2011. Residency of people involved in crashes can be derived from postcodes collected by police forces. The figures in this profile refer to casualties and drivers with postcodes in Oxford City. This dataset, including full residency information, is available to the road safety community for detailed analysis in MAST Online. A less complete version of STATS19, which does not include residency information, can be downloaded as a raw dataset from HM Government's transparency website at data.gov.uk. Residency profiles assess risk on the basis of where people live rather than where they crash because residency is the most appropriate basis for measuring socio-demographic factors which influence road risk. Since about two out of every five crash victims are injured outside the district where they live, it is inadvisable simply to equate 'crashes on local roads' with 'risk to local population'. Factors such as commuting and through traffic travelling long distances can result in substantial differences between the type of risk encountered on a road network and the risk to people who live in communities nearby.
Quality of postcode data While collection of postcode data as part of STATS19 is substantial and improving, it is not absolutely complete. Nationally, about 20% of casualties and drivers have no postcode reported in police STATS19 returns. Considerable local variation between police forces is also found, with missing postcode rates ranging from as low as 5% in some areas to as much as 43% in others. However, casualties and drivers with missing postcodes have been included in this analysis. For these cases, the most likely distribution of residency has been estimated using an algorithm specially constructed by RSA. The technique used is explained in detail in an appendix to this report. It is necessary to adjust casualty figures in this way for three reasons. Firstly, it ensures that the overall casualty total when reporting resident risk agrees exactly with figures published by the Department for Transport in REPORTED ROAD CASUALTIES GREAT BRITAIN. Secondly, it improves relevance and reliability by providing the largest possible sample size. Thirdly, it minimises distortion of casualty rates due to local postcode reporting practices: if no adjustment was made, then residents in police forces which report relatively few postcodes would seem to experience deceptively low risk, while conversely residents in forces which report almost all postcodes would appear to face misleadingly high risk.
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OVERVIEW OF OXFORD CITY The English District council area of Oxford City (ONS code E07000178) covers an area of around 17.6 square miles. It had a total population of 153,662 approx based on 2010 mid-year estimates, placing it in the 2nd decile terms of population density (45th out of 379 districts).
OVERALL RESIDENT RISK This section calculates risk based on all residents of Oxford City who suffered any injury in reported crashes anywhere on Britain's roads over the six year period 2006 to 2011, regardless of age or road user type. It is likely that additional unreported casualties occurred, but no estimate of these can be included in this report. Oxford City's overall risk and progress in comparison to other areas is illustrated in Chart 3.
Resident casualties of any severity On average, approximately 474 casualties per year are reported among residents of Oxford City. These figures include slight injuries such as minor cuts, bruises, shock and whiplash. This equates to an injury rate of one in every 324 residents each year. In comparison, the national rate is one in every 264 British residents each year. Consequently, Oxford City's national injury risk index is 82, where a value of 100 represents the national rate. This means that injury risk experienced by residents of Oxford City is 18% lower than the national average. Oxford City has a national injury risk ranking of 330th (where first place indicates the highest risk), placing it in the 9th decile of injury risk across 379 districts in Britain.
Resident killed or seriously injured (KSI) casualties On average, approximately 72 casualties per year are reported as killed or seriously injured among residents of Oxford City. This figure includes an average of 4 casualties per year who were killed, but excludes all slight injuries. This equates to a KSI rate of one in every 2,149 residents each year. In comparison, the national KSI rate is one in every 2,165 British residents each year. A comparison of KSI to overall risk is illustrated in Chart 1. Consequently, Oxford City's national KSI risk index is 101, where a value of 100 represents the national rate. This means that KSI risk experienced by residents of Oxford City is 1% higher than the national average. Oxford City has a national KSI risk ranking of 190th (where first place indicates the highest risk), placing it in the 5th decile of KSI risk across 379 districts in Britain.
Progress in reducing resident risk These statistics measure the change in road casualty risk over time for residents of Oxford City. The local trend is established by comparing a baseline (2006 to 2008) to the most recent information available (2009 to 2011). Progress is assessed by evaluating this trend relative to nationwide change over the same period. A comparison of recent progress to overall risk is illustrated in Chart 1. The average number of resident casualties has changed by -71 casualties per year over three years. This includes a change in resident KSI casualties of +9 casualties per year over three years. Oxford City has an injury progress index of 100, where a value of 100 represents the national rate of progress and higher values indicate less progress. The corresponding KSI progress index is 130. This means that progress in improving the injury risk experienced by residents of Oxford City is equal to the national rate over the last three years, while progress in improving KSI risk is 30% slower than the national rate.
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Oxford City's national injury progress ranking is 217th (where first place indicates the best progress), placing it in the 6th decile of progress across 379 districts in Britain. The corresponding KSI progress ranking is 364th, placing Oxford City in the 10th decile of progress.
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RESIDENT RISK BY AGE GROUP This section calculates risk for different age groups of Oxford City's residents who suffered injury in reported crashes anywhere on Britain's roads over the six year period 2006 to 2011, regardless of road user type. It is likely that additional unreported casualties occurred. Progress rankings have been calculated for each group using the same technique as that used for progress in risk to all residents. A comparison of risk for individual age groups to overall risk is illustrated in Chart 1.
Resident child casualties Oxford City's child population based on 2010 mid-year estimates is 24,649 approx. For the purposes of this analysis, children are all persons under the age of 16. On average, approximately 42 casualties per year are reported among children resident in Oxford City. This equates to a rate of one in every 582 resident chidren each year. In comparison, the national child injury rate is one in every 514 British resident children each year. Consequently, Oxford City's national child injury risk index is 88, where a value of 100 represents the national rate. This means that injury risk experienced by child residents of Oxford City is 12% lower than the national average for the same age group. Oxford City has a national child injury risk ranking of 221st (where first place indicates the highest risk), placing it in the 6th decile of child injury risk across 379 districts in Britain. The average number of child resident casualties has changed by -14 casualties per year over three years. Oxford City has a child injury progress index of 89, where a value of 100 represents the national rate of progress and higher values indicate less progress. This means that progress in improving the injury risk experienced by children resident in Oxford City is 11% faster than the national rate over the last three years. Oxford City's national child injury progress ranking is 99th (where first place indicates the best progress), placing it in the 3rd decile of progress across 379 districts in Britain.
Resident young adult casualties Oxford City's young adult population based on 2010 mid-year estimates is 37,058 approx. For the purposes of this analysis, young adults are all persons aged between 16 and 24 inclusive. On average, approximately 128 casualties per year are reported among young adult residents of Oxford City. This equates to a rate of one in every 290 young adult residents each year. In comparison, the national young adult injury rate is one in every 124 British young adult residents each year. Consequently, Oxford City's national young adult injury risk index is 43, where a value of 100 represents the national rate. This means that injury risk experienced by young adult residents of Oxford City is 57% lower than the national average for the same age group. Oxford City has a national young adult injury risk ranking of 376th (where first place indicates the highest risk), placing it in the 10th decile of young adult injury risk across 379 districts in Britain. The average number of young adult resident casualties has changed by -19 casualties per year over three years. Oxford City has a young adult injury progress index of 104, where a value of 100 represents the national rate of progress and higher values indicate less progress. This means that progress in improving the injury risk experienced by young adult residents of Oxford City is 4% slower than the national rate over the last three years. Oxford City's national young adult injury progress ranking is 255th (where first place indicates the best progress), placing it in the 7th decile of progress across 379 districts in Britain.
Resident adult casualties This section analyses the road safety profile of adults aged between 25 and 59 inclusive. Oxford City's population in this age group is 69,579 approx, based on 2010 mid-year estimates. On average, approximately 256 casualties per year are reported among adult residents of Oxford City. This equates to a rate of one in every 272 adult residents each year. In comparison, the national adult injury rate is one in every 238 British adult residents each year. 6|Page
Consequently, Oxford City's national adult injury risk index is 88, where a value of 100 represents the national rate. This means that injury risk experienced by adult residents of Oxford City is 12% lower than the national average for the same age group. Oxford City has a national adult injury risk ranking of 296th (where first place indicates the highest risk), placing it in the 8th decile of adult injury risk across 379 districts in Britain. The average number of adult resident casualties has changed by -31 casualties per year over three years. Oxford City has an adult injury progress index of 101, where a value of 100 represents the national rate of progress and higher values indicate less progress. This means that progress in improving the injury risk experienced by adult residents of Oxford City is 1% slower than the national rate over the last three years. Oxford City's national adult injury progress ranking is 228th (where first place indicates the best progress), placing it in the 6th decile of progress across 379 districts in Britain.
Resident senior casualties Oxford City's senior population based on 2010 mid-year estimates is 22,376 approx. For the purposes of this analysis, seniors are all persons aged 60 or more. On average, approximately 38 casualties per year are reported among senior residents of Oxford City. This equates to a rate of one in every 594 senior residents each year. In comparison, the national senior injury rate is one in every 556 British senior residents each year. Consequently, Oxford City's national senior injury risk index is 94, where a value of 100 represents the national rate. This means that injury risk experienced by senior residents of Oxford City is 6% lower than the national average for the same age group. Oxford City has a national senior injury risk ranking of 242nd (where first place indicates the highest risk), placing it in the 7th decile of senior injury risk across 379 districts in Britain. The average number of senior resident casualties has changed by +3 casualties per year over three years. Oxford City has a senior injury progress index of 115, where a value of 100 represents the national rate of progress and higher values indicate less progress. This means that progress in improving the injury risk experienced by senior residents of Oxford City is 15% slower than the national rate over the last three years. Oxford City's national senior injury progress ranking is 307th (where first place indicates the best progress), placing it in the 9th decile of progress across 379 districts in Britain.
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RESIDENT RISK FOR VULNERABLE ROAD USER GROUPS This section assesses risk among those Oxford City residents who may be among the most vulnerable to injury or crash involvement. Like other sections of this report which address resident risk, the scope of this section covers all reported crashes anywhere on Britain's roads over the six year period 2006 to 2011. It is likely that additional unreported crashes involving Oxford City residents occurred. Progress indices and rankings are only available in categories where sample sizes are generally large enough for results to be meaningful. A comparison of risk between different road user groups is illustrated in Chart 2.
Resident pedestrian casualties On average, approximately 54 casualties per year are reported as pedestrians resident in Oxford City. This equates to a rate of one in every 2,837 residents each year. In comparison, the national pedestrian injury rate is one in every 2,152 British residents each year. Consequently, Oxford City's pedestrian injury risk index is 76, where a value of 100 represents the national rate. This means that pedestrian injury risk experienced by residents of Oxford City is 24% lower than the national average. Oxford City has a national pedestrian injury risk ranking of 234th (where first place indicates the highest risk), placing it in the 7th decile of pedestrian injury risk across 379 districts in Britain. The average number of pedestrian resident casualties has changed by 0 casualties per year over three years. Oxford City has a pedestrian injury progress index of 112, where a value of 100 represents the national rate of progress and higher values indicate less progress. This means that progress in improving the pedestrian injury risk experienced by residents of Oxford City is 12% slower than the national rate over the last three years. Oxford City's national pedestrian injury progress ranking is 297th (where first place indicates the best progress), placing it in the 8th decile of progress across 379 districts in Britain. A comparison of pedestrian progress to overall pedestrian risk is illustrated in Chart 2.
Resident pedal cycle user casualties On average, approximately 133 casualties per year are reported as pedal cycle users resident in Oxford City. This equates to a rate of one in every 1,157 residents each year. In comparison, the national cyclist injury rate is one in every 3,551 British residents each year. These figures include both pedal cycle riders and pillion passengers reported as injured in crashes. Consequently, Oxford City's cyclist injury risk index is 307, where a value of 100 represents the national rate. This means that cyclist injury risk experienced by residents of Oxford City is 207% than the national average. Oxford City has a national cyclist injury risk ranking of 6th (where first place indicates the highest risk), placing it in the 1st decile of cyclist injury risk across 379 districts in Britain.
Resident motorcycle user casualties In order to improve insight into local issues and priorities, motorcycle user risk has been split into two categories for separate analysis. For the purpose of this report, large motorcycles include all powered two wheeled vehicles with a reported engine capacity of 125 cc or over. Small motorcycles include mopeds and all other powered two wheeled vehicles with a reported engine capacity under 125 cc. All figures include both riders and pillion passengers reported as injured in crashes. Large motorcycle user casualties On average, approximately 20 casualties per yearare reported as large motorcycle users resident in Oxford City. This equates to a rate of one in every 7,813 residents each year. In comparison, the national large MC user injury rate is one in every 5,280 British residents each year. Consequently, Oxford City's large MC user injury risk index is 68, where a value of 100 represents the national rate. This means that large MC user injury risk experienced by residents of Oxford City is 32% lower than the national average. Oxford City has a 8|Page
national large MC user injury risk ranking of 335th (where first place indicates the highest risk), placing it in the 9th decile of large MC user injury risk across 379 districts in Britain. Small motorcycle user casualties On average, approximately 17 casualties per yearare reported as small motorcycle users resident in Oxford City. This equates to a rate of one in every 9,039 residents each year. In comparison, the national small MC user injury rate is one in every 6,132 British residents each year. Consequently, Oxford City's small MC user injury risk index is 68, where a value of 100 represents the national rate. This means that small MC user injury risk experienced by residents of Oxford City is 32%lowerthan the national average. Oxford City has a national small MC user injury risk ranking of 291st (where first place indicates the highest risk), placing it in the 8th decile of small MC user injury risk across 379 districts in Britain.
Resident young adult drivers Unlike other assessments of resident risk in this profile, this section is not restricted to examining casualties of reported crashes. Instead, it focuses on all drivers involved in crashes, regardless of personal injury. This approach is used to scrutinise the exposure of younger drivers to risk. All analysis within this section excludes riders of pedal cycles, motorcycles and mopeds, since risk for these road user groups has been considered separately. For the purposes of this analysis, young adults are all persons aged between 16 and 24 inclusive. Sixteen year olds have been included because reliable population estimates are not available for age groups which start at seventeen. Oxford City's young adult population based on 2010 mid-year estimates is 37,058 approx. On average, approximately 72 drivers per year among young adults resident in Oxford City are reported as being involved in an injury crash. This equates to a rate of one in every 512 young adult residents each year. In comparison, the national young adult driver involvement rate is one in every 150 British young adult residents each year. In order to place young driver involvement into perspective, it is useful to compare this rate to the equivalent for all drivers of any age. The involvement rate for all drivers resident in Oxford City is one in every 296 residents aged 16+ each year, compared to the national rate of one in every 183 British residents aged 16+ each year. Oxford City's young adult driver involvement risk index is 29, where a value of 100 represents the national rate. This means that the driver involvement risk experienced by young adult residents of Oxford City is 71% lower than the national average. Oxford City has a national young adult driver involvement risk ranking of 373rd (where first place indicates the highest risk), placing it in the 10th decile of young adult driver involvement risk across 379 districts in Britain. The average number of young adult drivers involved in crashes has changed by -26 drivers per year over three years. Oxford City has a young adult driver involvement progress index of 92, where a value of 100 represents the national rate of progress and higher values indicate less progress. This means that progress in improving the young adult driver involvement risk experienced by residents of Oxford City is 8% faster than the national rate over the last three years. Oxford City's national young adult driver involvement progress ranking is 71st (where first place indicates the best progress), placing it in the 2nd decile of progress across 379 districts in Britain. A comparison of young driver progress to overall young driver risk is illustrated in Chart 2.
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APPENDIX Data sources Reported road casualties by residency: MAST Online http://www.roadsafetyanalysis.org/mast-online/ Subset of raw STATS19 dataset released by HM Government: Data.gov.uk http://data.gov.uk/dataset/road-accidents-safety-data Population and area in England and Wales: Office for National Statistics http://www.ons.gov.uk/ons/taxonomy/index.html?nscl=Population+Estimates Population and area in Scotland: General Register Office for Scotland http://www.gro-scotland.gov.uk/statistics/theme/population/estimates/mid-year/index.html
Correction for missing postcode data Because SIGNPOST SERIES profiles calculate resident risk by population, it is necessary to correct for regional variation in postcode reporting. Otherwise, areas in force areas which are poor at reporting postcodes would have lower resident casualty figures and therefore better risk rates than they should, but forces which are meticulous at reporting would be penalised. This would be inaccurate, misleading and unfair. It is also important to ensure that the total number of casualties attributed to every authority in the report added up exactly to the overall total, so local risk rates can be compared directly to each other and meaningfully to the national rate. The procedure below describes in detail how adjusted authority resident casualty figures are derived. Each step is illustrated by an example, involving two fictional entities: a police force called Southshire Constabulary, and the unitary council area of Northtown Borough Council which is elsewhere in the country, far from Southshire. 1. The following data was extracted from MAST Online: a. Casualties with unknown postcodes reported by each force in Britain; Southshire Constabulary had 8,381 casualties where Casualty Home was 'Unknown' b. Total casualties reported by each force in Britain, from which the number of postcodes successfully reported by each force was calculated; Southshire Constabulary reported 47,400 casualties altogether, so they reported 39,019 casualty postcodes (47,400 minus 8,381) c. All casualties categorised by authority area of residency according to reported postcode, broken down by the force area in which the crash occurred. There were a total of 4,882 casualties reported across Britain with a Northtown postcode, of which 183 were reported as injured in a crash in the Southshire Constabulary force area 2. For each home authority, the proportion of residents known to have crashed in each police force area was calculated. 3.75% of Northtown resident casualties sustained their injury in Southshire (183 divided by 4,882) 3. For each combination of home authority and police force area of crash, the proportion of all casualties in that police force area who were known to live in the authority in question was calculated. 0.47% of all postcodes reported by Southshire Constabulary are in Northtown, calculated as 183 divided by 39,019 4. The number of unknown casualties reported by each force from each authority was calculated, assuming that unknown casualties follow the same distribution as the known ones. About 39.3 of Southshire's unknown casualties were assigned to Northtown (0.47% of 8,381) 10 | P a g e
5. The adjusted casualty total for each combination of home authority and police force area of crash was calculated. About 222.3 Northtown residents were included in the total casualties reported by Southshire Constabulary , 183 with known postcodes plus an assumed 39.3 from casualties with unknown postcodes 6. These calculations were checked by adding up the adjusted totals for all authorities. The result is exactly equivalent to the actual casualty total as published in REPORTED ROAD CASUALTIES GREAT BRITAIN and MAST Online. 7. Exactly the same process was repeated for casualty and driver figures for each relevant each road user group, to derive a distinct set of correction factors for each. Southshire Constabulary reported 3,924 child casualties in the force area including 919 missing postcodes, and 5 Northtown resident children were known to have suffered injury in Southshire out of a total of 291 known Northtown resident child casualties altogether This algorithm makes certain assumptions, which may affect the results to some degree. These assumptions and their possible consequences are made explicit below. 
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Missing casualty postcodes arise mainly because of internal reporting practices within police forces, so all reporting of postcodes in STATS19 by any given force is probably affected to about the same extent regardless of where each individual casualty resides. However, if reporting officers were significantly more likely to report recognised local postcodes than less familiar ones, then this calculation could slightly overestimate resident casualty figures for authorities with unusually high concentrations of local casualties (often more rural or remote areas), and conversely slightly underestimate for authorities with high concentrations of non resident casualties (often those in urban areas or with long stretches of trunk routes). The reporting of foreign resident casualties in STATS19 is unreliable. In principle, foreign residents should be reported with the special code'2' in place of the postcode, but in practice only 3,019 instances of this were returned between 2006 and 2011. If taken at face value this would mean that only 0.22% of all casualties on Britain's roads (1 casualty in every 454) were foreign residents, and that they account for only 1.4% of all casualties reported without a postcode. However, anecdotal evidence and common sense suggest that there is widespread and significant under-reporting of foreign resident casualties. There are significant inconsistencies between forces in recording foreign residents. For instance Kent Police reported only eight casualty postcodes with '2' over the entire six year period while Northern Police, which lies hundreds of miles distant from most major points of entry to Britain and is over five times smaller in terms of population, reported 295 in the same period. Since there is insufficient data to represent foreign resident casualties in a robust manner, the only consistent course of action is to distribute all casualties without postcodes as if they were British residents, including the relatively few records which contain the official foreign resident STATS19 code. This assumption will increase all adjusted resident casualty figures to a small but unquantifiable extent. It may also disproportionately affect a few authorities where an unusually high number of casualties reported in the local force area could in fact be foreign residents (often those containing heavily used points of entry to Britain), or where the code '2' is in fact widely reported.
Postcodes in Northern Ireland are reported as 'Unknown', because casualty figures on Northern Ireland's roads do not fall in the scope of STATS19 reporting and therefore are not yet included in MAST. Consequently, the considerations explained above concerning authorities with unusually high foreign resident casualty rates may also apply to any authorities where an unusually high number of casualties reported in the local force area could in fact be residents of Northern Ireland.
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Chart 1 - Oxford City Resident Risk and Progress Indices - Age Bands (2006 - 2011) 160
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140 [Solid Bars] National Risk Index (high index = greater risk)
130
120 120 110 101 100
100 82
88
43
88
94 90
80 80
70 60 60
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All Casualties
KSI Casualties
Child Casualties
Young Adult Casualties
Adult Casualties
Senior Casualties
[Dashed Lines] Progress Index - last three years (high index = less progress)
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Chart 2 - Oxford City Resident Risk and Progress Indices - Road User Type (2006 - 2011) 180
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[Solid Bars] National Risk Index (high index = greaterer risk)
130 140 120
120
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307 100
100 76
26
68
68
68
90 80
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40 60
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Pedestrian Casualties
Young Adult Drivers
Drivers
Pedal Cycle Casualties
Large MC Casualties
Small MC Casualties
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[Dashed Lines] Progress Index - last three years (high index = less progress)
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Chart 3 - Local Authority District Resident Risk: Performance and Progress (2006 - 2011) 140
Low risk, less improvement
High risk, less improvement
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Oxford City Recent Progress Index
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100
90
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Low risk, more improvement
High risk, more improvement
60 20
40
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All Resident Casualties Index
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