Percentage reduction in road traffic collisions (FOI)
Percentage reduction in road traffic collisions (FOI)Produced by the Freedom of Information office
Authored by Government of Jersey and published on 10 July 2023.
Prepared internally, no external costs.
Please advise what the percentage reduction in road traffic collisions are on every road in Jersey that has had its speed limit reduced in the last 10 years. Please provide statistical proof that reducing speed limits has a positive effect on the safety of the road.
The Road Traffic (speed limits) (Jersey) Order 2003 Table of Legislation History lists all roads that have had their speed limits changed since 2003.
Road Traffic (Speed Limits) (Jersey) Order 2003 (jerseylaw.je)
Please also find attached an Excel spreadsheet of all road traffic collisions (RTCs) that have been reported to the States of Jersey Police since 2008. This is to allow you to analyse comparisons on any particular road from five years before the first date of the requested time frame (2013 to 2023) where a road speed was changed. The data excludes 1,450 RTCs where the locations are not recorded.
The States of Jersey Police do not hold details of the percentage reduction in road traffic collisions on every road in Jersey that has had its speed limit reduced in the last 10 years. There is no obligation to create data not held, therefore Article 10 (1) of the Freedom of Information (Jersey) Law applies.
Infrastructure and Environment department response
Jersey has a higher casualty rate per head of population than mainland Great Britain, and most British islands. Moreover, the proportion of vulnerable users involved in collisions is significantly higher when compared to rates for similar road users (pedestrians, cyclists, mopeds and motorcycles, horse riders) in Great Britain. Figures 1 and 2 at the foot of this response show Jersey trends in more detail.
The causal factors relating to road traffic casualties are multifaceted and generally fall into three categories: environmental, vehicle, and human, with the human factor being by far the leading determinant. Determining the cause of a road traffic collision is complex and requires large and consistent data sets to identify trends and causal links.
Whilst Jersey casualty rates are higher than those of similar jurisdictions, when individual roads are looked at, in statistical terms, the sample sizes are small, and no statistical significance can be read into the results.
As it is difficult to use Jersey’s road traffic collision data to establish statistically reliable trends at an individual road level, Jersey’s speed limit policy has been developed in the light of reliable national and international research, such as that published by the Royal Society for the Prevention of Accidents (RoSPA) which demonstrates that reducing speed limits has a positive effect on road safety. The policy was agreed by the Minister for Infrastructure with the Comité des Connétables, Honorary police forces and the States of Jersey Police and lodged with the States Assembly in 2016. These studies consistently demonstrate that appropriate reductions in speed limits reduce harm on road networks. Jersey’s speed limits policy recognises that there is a clear relationship between vehicle speed and collision severity, especially with regards to vulnerable road users.
Framework for Speed Limits.pdf (gov.je)
Jersey Road Safety Action Plan 2017 to 2019.pdf (gov.je)
The Island Road Safety Review, lodged with the States Assembly in December 2021 has both raised the profile of road safety, and committed thinking, practice and resources to significantly reducing casualties over the whole road safety spectrum, not just utilising speed management.
Island Road Safety Review December 2021.pdf (gov.je)
Please also see the Jersey Road Safety Action Plan 2017 to 2019 linked above.
The graph below shows killed and seriously injured road traffic casualties in Jersey over time.
The graph in Figure 1 attached shows killed and seriously injured road traffic casualities in Jersey over time.
Rolling averages are three-year mean averages and are used to show long term trends whilst minimising the extent of random fluctuation that the figures for individual years contain.
The further graph below shows casualty numbers in recent years by road user group and demonstrate that whilst car occupant casualties have fallen, casualties amongst other road user groups have not.
The graph in Figure 2 attached shows casualty numbers in recent years by road user group and demonstrate that whilst car occupant casualties have fallen, casualties amongst other road user groups have not.
Data for 2020 and 2021 is not considered typical due to lower traffic levels due to the Covid restrictions that were in place and has been omitted from I&E’s analytical work.
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