What are the main causes of cycling crashes?

Answer

Mostly it is a combination of several factors which leads to a road crash. In the occurrence of a bicycle crash factors related to infrastructure, vehicle and behaviour play a role. Often there is also a combination of unsafe behaviour of the cyclist and unsafe behaviour of another road user.

Infrastructure as (part of) the cause

Both the quality and the general layout of the infrastructure play a role in the occurrence and outcome of bicycle crashes.  A poor quality of the road surface (e.g. pits, trenches, drain covers, embankments by tree) is often the reason for a single-bicycle crash [6] [7]. Pits and bumps, for instance, play a role in 6% of the single-bicycle crashes [7]. Nearly one third of the single-bicycle crashes involving race cyclists occur on a (very) slippery road surface and when there are lengthwise trenches. The proportions for mountain bikes and hybrid bikes are 13 and 16% respectively [7].

Other infrastructure factors in the occurrence and outcome of bicycle crashes are the visibility of obstacles, the road course and the width of bicycle paths and lanes [8]. Additional infrastructure factors to improve safety for cyclists mentioned by the Dutch Cycling Association [9] are:

  • car traffic using a coarse main road network with a limited number of side roads;
  • good quality cycle routes through and between residential areas; and
  • good crossing facilities at locations where cyclists need to cross the car network.

Vehicle as (part of) the cause

The extent to which the vehicle – in this case the bicycle – has played a role in causing the crash is difficult to establish and is also not systematically registered. However, it is clear that when riding a bicycle there is always a risk of falling, because it is a vehicle requiring balance that is inherently unstable [10] [11]. The bicycle type may also influence safety; different bicycle types have different riding positions, ease with which one can put the feet on the ground, and ease with which one mounts and dismounts [3]. One also slips sooner on a bicycle with narrow tyres than on a bicycle with wide tyres.

A safe bicycle has a sound frame construction, good brakes and lighting, and well-profiled tyres [11]. Senior cyclists(65 and older) often have a different way of mounting, starting and dismounting, which makes it harder to maintain one’s balance [12] [13]. They could benefit from specially designed tricycles that can prevent  a fall when mounting and dismounting [3] [11] [14].

Behaviour as (part of) the cause

Unsafe traffic behaviour of other road users, e.g. speeding, distraction, red light running, driving under the influence, increases the risk of crashes, in particular also the risk of crashes with cyclists [15]. Also the unsafe behaviour of cyclists themselves, e.g. smartphone use, cycling under the influence, cycling without good bike ligths, increases the risk of  a crash. Often there is also a combination of the above unsafe behaviour by both cyclist and fellow-road user.