Research into cycling road traffic collisions has identified a list of common collision scenarios for Ireland and underlined previously underappreciated issues on our roads.

Among other things, the research shows the importance of studying single-cyclist collisions (those involving no other road user) – with poor road surface conditions (slippery road surfaces, debris, or potholes), LUAS (tram) tracks, and kerbs highlighted as being commonly involved in such incidents.

A number of key findings emerged from a detailed analysis that used self-reported collision data. The researchers behind the study found that garda and hospital data paint an incomplete picture of the cyclist safety problem.

Roughly 75% of respondents involved in injurious collisions did not report the incident to the gardai. Furthermore, the findings indicate that many lower severity injuries do not appear in hospital data. The data coverage and underreporting issues highlighted in this study are not unique to Ireland – internationally, injury prevention efforts are transitioning from a focus on fatalities and serious injuries to include less severe collisions.

Key findings

  • Single-cyclist collisions (those involving no other road user) are very common in Ireland, and they are the least likely collision type to be reported to the gardai with fewer than 4% reported
  • Loss of tyre traction due to slippery road conditions, and interactions with LUAS (tram) tracks, kerbs, and potholes are key factors
  • Single-cyclist collisions often have more than one contributory factor
  • For collisions with bonnet-type vehicles (eg cars), nearside (left)-hook, vehicle lane changing, and overtaking manoeuvres are common
  • Impacts with vehicle sides and doors are also common

Kevin Gildea, PhD candidate in Trinity’s School of Engineering, is the first author of the research, which has just been published in the journal Accident Analysis and Prevention

He said: “The study highlights in particular the high prevalence of collisions in urban environments preceded by the cyclist and vehicle travelling in the same direction, such as vehicle overtaking/passing or lane changing, or left-hooks at intersections, highlighting the need for safety interventions both along roadways and at intersections.

"Dooring collisions also pose a high risk for cyclists, highlighting the need for educational campaigns – like Dutch Reach – and automated vehicle safety systems to reduce their occurrence.

"For single cyclist collisions, the study highlights how common falls involving poor road surfaces, involving slippery road surfaces, debris, and potholes, LUAS/tram tracks, and kerbs are.

"The findings for tram tracks are particularly striking, considering the fact that they are only present on certain sections of the road network in Dublin city. These findings highlight the importance of road/cycle lane maintenance efforts, and infrastructural interventions to improve the forgivingness of road furniture, particularly around tram tracks, and kerbs – especially at locations where cyclists are expected to enter/exit cycle lanes or interact with tracks.

“Although a number of the scenarios that we have identified were previously known to pose risks to cyclists in Ireland, and good work has been done to reduce their risks – through educational campaigns and infrastructural interventions – this work adds context and has allowed us to identify a list of priority representative cyclist collision scenarios for Ireland.

"The findings are particularly relevant to road safety bodies and road infrastructural planners and should also have good use in the fields of injury biomechanics, and automated vehicle safety.”

Furthermore, the researchers underline that the scale of the underreporting problem highlighted in this study (for cyclist collisions in particular) adds to the importance that road safety stakeholders make increased efforts to address cyclist safety issues.

Safety-in-numbers effect

Internationally, efforts are transitioning from a focus on fatal and serious injuries to include less severe collisions, which merit investigation due to their high frequency, often long-term effects, and because they discourage cycling, which in turn reduces modal share and safety via the safety-in-numbers effect.

Due to the self-reporting nature of the study these results do not include fatal cyclist collisions. The researchers are currently extending their analysis to include fatalities.

Ciaran Simms, professor in Trinity’s School of Engineering, supervised the research. He added: “I am delighted that the Road Safety Authority has funded this research into cyclist safety in Ireland.

“Common collision scenarios vary between countries and cycling environments, but in this study, we designed a detailed coding scheme to characterise single-cyclist collisions which can also act as a basis for identifying common collision scenarios in other countries.

“In addition, we are now keen to shed further light on the cause(s) and frequency of single-cyclist collisions in Ireland – because our findings have highlighted their importance and because they have not been well investigated in the past. We will also work to investigate cyclist interactions and falls on tram tracks in Dublin – which played a role in 23% of the single-cyclist falls in our data.”

The research reported here was funded by the Road Safety Authority’s RSA-Helena Winters Scholarship for Studies in Road Safety.

The full research paper can be read and downloaded here.