[caption id="attachment_30786" align="aligncenter" width="560" caption="Bike/car fatality and injury risk for cyclists vs car occupants in Sydney (based on Garrard et al)"]
I’ve previously questioned the surprisingly common view that cycling on roads isn’t dangerous. In this article, Does cycling on roads put your health at risk?
, I pointed to data released by Transport for London
which suggests cycling in London is more dangerous than any other mode except motor cycling.
In another article, Do Coroners sometimes go too far?
, I cited a study that calculated the risk for Australian children of travelling to school by bus relative to other modes. When exposure is accounted for (i.e. kms of travel), taking the bus is 1.4 times safer in terms of the risk of death or serious injury than being driven; 4.4 times safer than walking; and an extraordinary 55 times safer than cycling.
An economic appraisal of the proposed Inner Sydney Regional Bicycle Network
prepared by AECOM for the City of Sydney states that an increase in cycling at the expense of other modes would increase the total cost of accidents to the community.
Now a reader
has drawn my attention to a more recent Australian study, Cycling injuries in Australia: road safety’s blind spot?
, by J Garrard, S Greaves and A Ellison.
They looked at Police data on road crashes in Sydney over a four year period by mode and compared these against distance travelled (see exhibit). They estimate the relative risk of a fatality on a bicycle in Sydney was around 11-19 times higher than in a car. The researchers also looked at Police-generated crash data for Melbourne in 2007-08 and found the fatality risk for a cyclist travelling the same distance on the roads as a car driver or passenger was four and a half times that of a car occupant.
There's a large range in these estimates because the number of cyclist fatalities is small i.e. between 8 and 10 p.a. over four years in Sydney (compared to annual counts of 164-185 for car occupants) and 4 in Melbourne in 2007-08 (96 for car occupants). However in all cases the risk of fatality is much higher for cyclists.
The researchers also looked at injuries (where the numbers were much larger). The risk of suffering an injury in Sydney was 13-15 times higher for a cyclist, although injury severity isn't identified in NSW, so some relatively minor injuries will be included. Fortunately the Victorian data does discriminate by severity and the results are broadly similar; the risk of a serious injury in 2008-09 was 12.9 times greater for a cyclist than a car driver. (1)
In the case of Melbourne, the researchers also had access to hospital data on serious injuries suffered by cyclists and car travellers in 2007-08. While the numbers were essentially the same as the Police data in the case of cars, there were two and a half times as many serious cyclist injuries compared to the police data base, indicating many hospital presentations are the result of off-road incidents. If these cases are included, the relative risk of cycling compared with driving was 34 times higher in Melbourne.
The researchers go on to point out that cyclist injuries increased 109% in Melbourne between 2000 and 2008, and conclude that:
While road safety counter-measures have undoubtedly led to a safer operating environment for vehicle occupants, the (arguably) car-centric nature of many of these measures has in fact done little to improve cyclist safety. Cyclists appear to be over-represented in terms of fatalities and serious injuries relative to their exposure to traffic, but under-represented in interventions aimed at reducing traffic fatalities and injuries.
Caution is needed in interpreting the numbers because of the limitations of the data e.g. it's collected by staff whose main priority at the time of the incident isn't record keeping. Much more caution is needed though when interpreting fatality data presented by the Qld Transport Department
to the Parliamentary Inquiry Into Cycling Issues. The Department simply presented fatality data for various countries by dividing by population.
: another reader
commenting on a different article has cited this study, Injuries to pedal cyclists on New Zealand roads, 1988-2007
. She says it shows "the average number of serious (AIS>2) injuries per million hours spent travelling in 2003-07 was 6.2 for cyclists, 1.0 for pedestrians, and 0.8 for car/van drivers."
- It’s sometimes argued that using kilometres of travel can give a misleading impression because car trips tend to be longer than bicycle trips. In Melbourne, for example, the average weekday trip by car is 11.7 km compared to 5.3 km by bicycle. The average duration of travel however is similar: 20.5 minutes for cars versus 22.4 minutes for bicycles. (Note though that in their study for the City of Sydney, AECOM assumed an average 9 km trip distance for cycling). Even if that proposition is accepted, using time or the number of trips as the metric only halves the relative risk of bicycle travel in Melbourne in 2007-08. A cyclist is still around twice as likely to die and around six times more likely to suffer a serious injury than a driver if he or she cycles on the road. In any event, this argument only holds when the same trip is compared (as is the case here). On average, however, cyclists make fewer trips than drivers, so over the course of a year, total kilometres and hours spent on the road by all cyclists will be considerably lower than the corresponding figure for all drivers.