Advocates of higher speed limits are distorting the facts about road deaths

Alan Buckingham's condemnation of speed cameras relies on several distortions of crash statistics, artfully draped over a long-standing polemic advanced by speed advocates in the UK, Canada and America.

The worst distortion is the claim that speeding causes only seven per cent of crashes, which he derives from research by the UK Transport Research Laboratory. To arrive at this figure, Buckingham excludes crashes assigned to more explicit categories, such as slippery roads, aggressive driving, close following and weather. Of the Australian research, by the NSW Roads and Traffic Authority, Buckingham excludes causes such as jack-knifing, excessive speed for conditions, alcohol and fatigue.

However crashes in those more explicit categories are caused, enabled or exacerbated by speed, and will be neutralised by action against speeding. Jack-knifing, for example, typically occurs when a speeding truck fails to negotiate a turn and hits a ditch or embankment. Slippery roads and weather only become a problem if speed is too high. Aggressive driving frequently means tailgating, which is a favourite activity of the speedster.

It is entirely appropriate to include those precise categories in the aggregate figure for speed. The proportion of crashes caused by speed is not the small seven per cent claimed by Buckingham, but the 30 to 40 percent claimed by road safety experts.

Why crashes are biassed towards lower speeds

Buckingham's second claim is that speeding is safer because crashes predominantly occur at extremes of low and high speeds. This confuses crash speed with sustained travelling speed, and also ignores the distorting contribution of victim vehicles.

Reported speeds in crash incidents will always be biassed towards low speeds because crashes typically occur when one vehicle is entering or leaving the traffic stream, and thus travelling more slowly or even stopped. In such circumstances, the speed of the victim vehicle will contribute to the weighting towards slower speeds that Buckingham comments on, even though the victim vehicle did not cause the crash.

As well, aggressor vehicles usually brake before impact, reducing the impact speed and extent of damage to the victim vehicle, which is often used to estimate pre-crash travelling speed. It's also worth bearing in mind that, when they're interviewed by crash investigators, speeding drivers lie.

Buckingham also attempts to use the lower crash rates on freeways as an argument that speeding is safer. This ignores the fact that freeways are designed to be safer than suburban and rural roads. Freeways are specifically designed to exclude unexpected events such as sudden side entries, vehicles manouvering at low speed, people walking, cyclists and children appearing with little or no warning.

It is thus not valid to conclude, as Buckingham does, that speeding is safer. The TRL research that Buckingham refers to actually makes this point, and Buckingham acknowledges it in his formal paper in the Centre for Independent Studies journal, but not in the articles he wrote for high-circulation newspapers. This is curious. The TRL research specifically finds that, when entry/exit crashes are excluded, and road quality is controlled for, speeding causes more crashes.

Invalidation of this argument also invalidates a related claim by speed lobbyists - that crashes result from a difference between travelling speeds, with the implication that lawful drivers are responsible for this difference. The fact is that low travelling speeds do not correlate with a higher crash rate, and that speed differences arise from the unlawful behaviour of speedsters, not lawful drivers.

Third, experience in America contradicts Buckingham's thesis. When several western states increased speed limits on long distance roads in 1996, fatality rates on those roads rose 15 percent according to the respected Insurance Institute for Highway Safety. Texas increased speed limits even on simple 2-lane roads, and suffered a staggering 45 percent increase in fatalities on those roads, according to an article by Dana Milbank in the 23 September 1997 edition of the Wall Street Journal.

Speed advocates quibble about these figures, since whole-of-state figures in America continued to decline as part of the generalised long-standing decline in crash figures. The point is that the National Highway Transport and Safety Board specifically monitored the roads where speed limits were raised, and crash rates rose on those roads.

Fourth, the 85th percentile argument so beloved of speed advocates is also disproved by American experience. This argument holds that speed limits should be set to the 85th percentile of measured median speeds, regardless of existing speed limits. Speed advocates contend that raising the limit would simply accomodate the natural feel of the road, and bring most drivers into compliance with the new limit.

The reality is that 85th percentile speeds are usually 10 to 20 kmh faster than the limit, and represent the driver's judgement of the fastest speed he can get away with, rather than some natural characteristic of the road. American experience has been that, when speed limits increase, so do the 85th percentile measured speeds. My own experience on roads in the north of Victoria where the speed limit was lifted from 100 kph to 110 kph also concur with this observation. Even worse, America found that the proportion of extremely fast speedsters increases disproportionately.

Are recidivist drivers the reason for the plateau?

There are alternative explanations for the plateauing of crash rates, but Buckingham does not consider them. The most likely is simply that education and advocacy campaigns have reached all reasonable people, and are now stalled at a small hard core of drivers. Most population based trends follow similar patterns.

Another possible factor is that mobile phone usage, which started to become prominent in the mid 1990's, caused more crashes. Many studies have confirmed early findings by the New England Journal of Medicine that talking while driving increases crash risk four times, although mobile phone companies in America have tried to deny and obfuscate this link.

The rights of the rest of us

Crashes and run-downs generally occur when a driver fails to respond quickly enough to some unexpected event, such as a vehicle suddenly entering from a side street or a child running out from between parked cars. The faster the vehicle is travelling, the less time the driver has to avoid impact. This is indisputable.

On high speed 2-lane roads, the speedster is deadly for he or she engages in lots of overtaking, which exposes innocent oncoming traffic to combined speeds typically over 230 kmh.

Studies by professional road safety researchers in Australia have found that crashes and road deaths unequivocally decline where speed cameras are used. Evaluations by ARRB Transport Research, for example, found that fatalities declined by 74 percent at ACT sites, and by 95 percent at a sample of 28 sites in NSW. When Victoria introduced cameras in 1989, crashes dropped 46 percent over the succeeding three years. Buckingham airily dismisses this outstanding result by claiming the preceding year was unusual.

Speed advocates believe they should be trusted to make the judgement as to what speed is safe and preferable. Unfortunately, what seems safe to a business executive running late for a meeting is probably not safe to other parties, including lawful drivers, cyclists, walkers, children, parents, police and medical practitioners. That is why we have speed limits.

Public acceptance of speed cameras is high, according to the ARRB Transport Research study, with only 5-7 per cent of people surveyed saying the cameras provide no benefits. In America, a telephone survey of 6,000 drivers in 1997 found that 27 percent of drivers felt there was too little police enforcement on interstate roads and 40 percent felt that way about residential roads. Only 4 to 5 percent felt there was too much enforcement.

The pernicious elements of speeding ideology

Speed cameras attract widespread ire from speedsters for two reasons - cameras are effective and they're unbiased. They don't care whether the speedster is a politician, or is well dressed, or is driving an expensive car.

The result has been a range of attacks and rhetorical devices intended to shift blame from speeding, such as claims that drivers have better concentration when speeding and that lawful drivers are less skillful. The reality is that reduced response times don't translate to quicker or better responses. Further, it is speeding that requires less skill, not lawful driving. Any fool can put their foot down and pass other cars. It takes skill to maintain station in a fluid traffic environment, and skill to maintain a reserve of time and speed to handle untoward events.

Buckingham tries to impute the great decline in crashes from 1980 to something he calls a driving culture, which by implication is independent from road safety and enforcement programs. The fact is that the decline in crashes was shaped and driven by the very enforcement programs Buckingham is now complaining about. What's more, each time a new program such as drink driving was introduced, libertarian forces complained about and tried to stifle them. In America, driver groups still complain about seat belts and air bags. Buckingham argues that improvements in car safety created the safety improvements, yet America had the same car and road improvements, without the improvements in crash rates that we saw.

Some of Buckingham's arguments against speed cameras are blatant threats of unlawful behaviour, which sit oddly with the speed lobby's claims to wronged law-abiding citizens. These include threats to race through suburban streets to avoid cameras, to speed elsewhere to "make up time," and to use false number plates to avoid detection.

Conclusion

Buckingham's interpretation of crash statistics does not support his contention which, in any case, seems to largely represent a standard polemic of speed lobbyists. The evidence from professional road safety researchers is clear that speed cameras save lives.