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Speed limits reduction report (FOI)

Speed limits reduction report (FOI)

Produced by the Freedom of Information office
Authored by Government of Jersey and published on 31 August 2023.
Prepared internally, no external costs.


Please supply a copy of the report referenced in the Governemnt of Jersey's recent response to a petition about speed limits, which is cited in the response as indicating that on '20mph roads' there is a '21%' reduced chance of injury to cyclists compared with 30mph roads.  

Please explain what process of analysis and literature review was undertaken in order to assure ministers of the veracity and academic rigour of the 'report'. 

Please explain the Government of Jersey's precise understanding - in the abstract - of the concept of a '21% reduced chance' and how that understanding was developed and confirmed by persons with appropriate expertise before the response was approved for putting into the public domain. 


The research paper requested is accessible by other means. Article 23 of the Freedom of Information (Jersey) Law 2011 has been applied. Please see the following link:

Cycling injury risk in London: A case-control study exploring the impact of cycle volumes, motor vehicle volumes, and road characteristics including speed limits ( 

The literature review was caried out by Infrastructure and Environment’s Senior Traffic and Road Safety Engineers in conjunction with Senior Traffic and Road Safety Engineers from external contractors, WSP, under the direction of the Principal Engineer for Network Management.

The review pulled together the findings from a variety of sources and papers including the Department for Transport, Transport Research Laboratory, the British Medical Journal, The Road Safety Foundation, along with other sources including peer reviewed papers.

The research paper, linked above, cites in its findings that a 21% reduction in the chance of an injury occurring on a 20mph road when compared to a 30mph road.  This can also be expressed as a reduced probability of an incident occurring which results in an injury to the cyclist.  

Whilst the specific figures presented in the research paper may not translate identically to the Jersey highway environment, the overall trends are being mirrored in Jersey with analogous data being produced. 

Article applied

Article 23 - Information accessible to applicant by other means

(1) Information is absolutely exempt information if it is reasonably available to the applicant, otherwise than under this Law, whether or not free of charge.

(2) A scheduled public authority that refuses an application for information on this ground must make reasonable efforts to inform the applicant where the applicant may obtain the information.

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