Current limited evidence suggests there may be no difference in collision rates for general cycle routes or networks compared to none, or for cycle lanes compared to none. However, the quality of this evidence was generally low, which reduces the robustness of the data. Further well-designed studies generating more data to inform the review question are needed.
Overall summary Low risk of bias in the review
All domains were considered at low concern.
|A. Did the interpretation of findings address all of the concerns identified in Domains 1 to 4?||Probably yes|
|B. Was the relevance of identified studies to the review's research question appropriately considered?||Probably yes|
|C. Did the reviewers avoid emphasizing results on the basis of their statistical significance?||Probably yes|
|Risk of bias in the review||Low|
|Number of studies||21|
|Number of participants||Unclear|
|Last search date||March 2015|
|Objective||To determine the effects of different types of cycling infrastructure for reducing cycling injuries in cyclists.|
|Population||Adult or child cyclists.
Mixed age groups were included.
|Interventions||Cycling infrastructure that aims to manage the shared use of the road space for both motor vehicles and cyclists (cycle lanes, shared use of a bus lane, advanced stop lines, cycle routes and coloured lanes or stop lines); cycling infrastructure that separates cycle traffic from motorised traffic and may include special routes exclusively for cycle traffic, but which may be shared with pedestrians either in mixed or segregated conditions (cycle tracks and cycle paths); and management of the transport network (separation of traffic movements, cycle phases at traffic signals, speed management).|
|Comparator||Not pre-defined (ultimately included: no infrastructure or a different type of infrastructure)|
|Outcome||Primary outcomes: injuries (self-reported or medically attended) sustained as a result of cycling.
Secondary outcomes: collision rates for cyclists; cycle counts.
Studies with assessed collisions that occurred as a result of racing, mountain biking or playing (i.e. cycling a non-directional course) were excluded.
|Study design||Randomised controlled trials, cluster randomised controlled trials, controlled before-after studies and interrupted time series studies.|
Four studies reported on collision rates for cyclists at one to two years. Pooled analysis reported no difference in cyclist collision rates for cycle routes and networks compared to no cycle routes or networks (rate ratio (RR) 0.68 (95% confidence interval (CI) 0.31 to 1.47; 4 studies, n=18 sites). When taking into account cycle flow, pooled analysis similarly reported no difference in collison rates (RR 0.40 (95% CI 0.15 to 1.05; 3 studies). Similarly, pooled analysis reported no difference in cyclist collision rates for cycle lanes compared to no cycle lanes (RR 1.21, 95% CI 0.70 to 2.08; 3 studies).
Narrative analyses suggested that speed limits of 20 mph, changing parts of the road network to some designs of roundabouts and changing busy parts of a cycle route may reduce the risk of collision.
The eligibility criteria were generally well described (although the comparators were not pre-specified) and appeared appropriate to address the present review question. No restrictions were reported based on study characteristics or sources of information.
|1.1 Did the review adhere to pre-defined objectives and eligibility criteria?||Probably yes|
|1.2 Were the eligibility criteria appropriate for the review question?||Probably yes|
|1.3 Were eligibility criteria unambiguous?||Probably yes|
|1.4 Were all restrictions in eligibility criteria based on study characteristics appropriate (e.g. date, sample size, study quality, outcomes measured)?||Yes|
|1.5 Were any restrictions in eligibility criteria based on sources of information appropriate (e.g. publication status or format, language, availability of data)?||Yes|
|Concerns regarding specification of study eligibility criteria||Low|
Extensive searches were carried out on a variety of biomedical and transport-specific databases, including: the Cochrane Injuries Group Specialised Register, CENTRAL, MEDLINE (OvidSP), PubMed, EMBASE Classic, ISI Web of Science, Geobase, Open Sigle, Tranweb, Sustrans, Safetylit and TRID. In addition, websites (Pedestrian and Bicycle Information Center, Cycling Embassy of Great Britain, AAA Foundation for Traffic Safety, Australian Road Research Board, Swedish National Road and Transport Research Institute, Transport Canada, Transportation Research Board, Injury Control Resource Information Network, Harborview Injury Prevention and Research Center, CTC national cycling charity, American Society of Civil Engineers, Google Scholar) were searched, conference proceedings from the World Conference on Injury Prevention and Safety, Australian Cycling Conference, New Zealand Cycling Conference and the Velo-city Conference were handsearched, the reference lists of included studies and previously published reviews were screened and relevant organisations were contacted. The search strategy was reported in full and appeared adequate. There were no restrictions imposed based on date, publication format or language. Two review authors independently assessed titles and abstracts for inclusion in the review, and disagreements were resolved by a third review author.
|2.1 Did the search include an appropriate range of databases/electronic sources for published and unpublished reports?||Yes|
|2.2 Were methods additional to database searching used to identify relevant reports?||Yes|
|2.3 Were the terms and structure of the search strategy likely to retrieve as many eligible studies as possible?||Yes|
|2.4 Were restrictions based on date, publication format, or language appropriate?||Probably yes|
|2.5 Were efforts made to minimise error in selection of studies?||Yes|
|Concerns regarding methods used to identify and/or select studies||Low|
Two reviewers were independently involved in the data extraction process and any disagreements were resolved by consensus with a third reviewer. Sufficient study characteristics appear to have been extracted to allow interpretation of the results. The study results were appropriately collected for the synthesis. The methodological quality of included studies was assessed using appropriate criteria. Two reviewers were independently involved in the risk of bias assessment and any disagreements were resolved by consensus with a third reviewer.
|3.1 Were efforts made to minimise error in data collection?||Yes|
|3.2 Were sufficient study characteristics considered for both review authors and readers to be able to interpret the results?||Probably yes|
|3.3 Were all relevant study results collected for use in the synthesis?||Probably yes|
|3.4 Was risk of bias (or methodological quality) formally assessed using appropriate criteria?||Yes|
|3.5 Were efforts made to minimise error in risk of bias assessment?||Yes|
|Concerns regarding methods used to collect data and appraise studies||Low|
The synthesis appeared to include all eligible studies. The method of analysis was explained and appeared appropriate. The methods used to pool data appeared appropriate. Heterogeneity was assessed and found to be moderate for all outcomes; this was further investigated using subgroup analysis. Robustness of the findings cannot be performed due to the low number of studies. Quality of the individual studies was considered in the synthesis.
|4.1 Did the synthesis include all studies that it should?||Probably yes|
|4.2 Were all pre-defined analyses reported or departures explained?||Probably yes|
|4.3 Was the synthesis appropriate given the degree of similarity in the research questions, study designs and outcomes across included studies?||Probably yes|
|4.4 Was between-study variation minimal or addressed in the synthesis?||Probably yes|
|4.5 Were the findings robust, e.g. as demonstrated through funnel plot or sensitivity analyses?||Probably yes|
|4.6 Were biases in primary studies minimal or addressed in the synthesis?||Yes|
|Concerns regarding synthesis and findings||Low|