Cyclist injury data before and after
helmet law in Western Australia

The table above shows the proportion of head injuries had been falling before the mandatory bike helmet law was introduced in 1992. The actual number of skull fractures was 64 in 1990-1992 and 44 in 1993-1995 (-31.25%). Surveys indicate the number of cyclists on the Narrows dropped by 28% between 1991/92 and 1995/96. On the Causeway bridge, cyclist numbers dropped by 36% between 1991/92 and 1995/96.

The actual number of intracranial injuries was 423 in 1990-1992 and 403 in 1993-1995 (-4.8%). The estimated percentage of West Australian cyclists wearing helmets increased from 39% in 1991 to 77% in 1995.

Skull fractures usually don't inflict long-term disability and intracranial injuries mostly require less than one day of hospital treatment. Nevertheless, both injury types can be serious.

The decline in skull fractures in the three years after helmet law enforcement amounts to an average seven per year. The decline in intracranial injuries in the three years after helmet law enforcement also amounts to an average seven per year.

That's an average 14 less head injuries per year from a total bike ownership of more than 750,000 West Australians, and with tens of thousands of people giving up cycling after the law was enforced.

The actual number of head injuries fell marginally after helmet law enforcement. However, upper limb fractures rose sharply. Cyclist upper extremity injuries in Western Australia increased from 118 (16.9% of all injury locations) in 1988 to 274 (32.2%) in 1998.

Research by McDermott et al. (Trauma, 1993, p834-841) found a significant increase in neck injuries for helmet wearers. 3.3% of unhelmeted riders sustained neck injuries while 5.7% of helmeted riders sustained neck injuries - a 75% greater risk among helmet wearers. The study compared 366 helmeted riders and 1344 non helmeted riders admitted to hospital in the Australian state of Victoria before helmets were mandatory.

* No neck injuries because cyclists with a neck injury also sustained injury of the same severity to a higher ranking body region.

Table B9 / Bicycle Crashes and Injuries in Western Australia, 1987-2000 - Road Safety report RR131 (PDF 840kb) commissioned by Road Safety Council, dated November 2003 and authored by Lynn B. Meuleners, Arem L. Gavin, L. Rina Cercarelli and Delia Hendrie

Although head injuries represent a smaller percentage (or proportion) of overall cycling injuries, this is mostly because of a much greater number of upper body injuries within the smaller pool of cyclists on the roads.

In other words, upper body injuries replaced head injuries as the dominant injury following helmet law enforcement but mostly because the actual number of upper limb fractures rose so sharply.

Various factors explain the overall (all body) increase in injuries, which add to the public health / pollution / transport infrastructure consequences of having fewer cyclists.

These include greater risk-taking when wearing a helmet, an increase in head surface area likely to contact or graze a solid object, and greater brain injury through the added rotational force of the helmet - particularly soft tops which grip the road surface (see eMedicine for more detail).

A further reason for the failure to reduce overall injury numbers is that tens of thousands of citizens who have abandoned cycling are instead driving their cars, increasing traffic density and further endangering all road users including pedestrians, other motorists and the remaining cyclists.

Cartoon thanks to Yehuda Moon and the Kickstand Cyclery

West Australian Health Department data allows a comparison of injury rates during the three years before and the three years after all-age mandatory bicycle helmet law enforcement in 1992.

Following is a summary of the Health Department data linked above, showing actual and averaged numbers of hospitalised cyclist injury types in Western Australia on an annual basis:

Surveys consistently show that cyclist numbers fell by approximately 30% from 1992 to 1995 (three years of helmet law enforcement).

When this 30% reduction in public cycling numbers is considered, the above results suggest a slight improvement in skull fractures and a worsening in intracranial injuries (which should have averaged close to 100 per year following law enforcement).

Despite far fewer cyclists, the numbers of non-head injuries either remained fairly static or, in the case of upper limb fractures, worsened markedly.

Age-standardised rates of hospital admissions for injuries sustained in bicycle and vehicle crashes

Above is a West Australian Health Department graph comparing hospital admissions for injuries sustained in bicycle and vehicle crashes from 1981 to 1995. There is no reduction in cyclist admissions after helmet law enforcement in 1992. It can be argued that the increase in vehicle crashes from 1992 coincided with July 1992 enforcement of the bicycle helmet law that caused tens of thousands of people to abandon cycling and instead drive their cars, increasing the injury risk for all road users.

According to the Australian Commonwealth Department of Transport, one third of all car journeys are estimated to be three kilometres or less and the average length of each bike trip is 2.5 km. Every day, Perth residents make 240,000 car trips that are less than one kilometre long.

Read the views of an Accident and Emergency doctor: "Forcing people to wear helmets demonstrably reduces the number willing to ride a bicycle. Less cycle use means more obesity, heart attacks, and use of other, less environmentally-friendly means of transport. Making helmet use compulsory gives cycling an undeservedly dangerous profile, and may discourage bicycle use even further."

America's Injury Prevention magazine published an article in 2003 titled Safety in Numbers: more walkers and bicyclists, safer walking and bicycling (PDF 140kb) which concludes that policies increasing walking and bicycling can improve the safety of other road users.