Lowering speed tolerance targets wrong drivers

18:44, Nov 28 2013

As a generally law-abiding and careful motorist who's been driving for 30 years with little more than a couple of fender-benders and two speeding fines in that entire time, I'm starting to feel like the police have me in their sights.

First it was the lowering of the drink-drive limit from 80mg to 50 despite a woeful lack of evidence that it will do anything to lower the road toll - or indeed that drivers in that range even cause many accidents (see my Sunday Star-Times column for more on why I believe the policy is flawed and this news story on how the crash statistics have been manipulated)

Now, police want to lower the tolerance for "speeding'' - or going faster than the posted limit - to just 4 kmh for an entire two-month period.

Motorists put up with this imposition on long weekends and public holidays because it's a special event, they know the police are going to be out in force during public holiday periods, and, who knows, maybe it even works for a short period of time (more about that in a minute).

But there's a big difference between imposing the restriction for a day or two and for 61 consecutive days throughout December and January - and the police are not ruling out the new rule becoming permanent.

The traditional 10 kmh tolerance exists for a series of good reasons. One, car speedometres are calibrated differently and are not accurate to more than plus or minus 5 kmh. In my vehicle, the difference between the speed reading off my GPS and the car speedo can be as much as 10 kmh.


Two, it's extremely difficult to maintain an absolutely constant speed unless you have cruise control. Try it. Sticking to a speed within a margin of 4 kmh is almost impossible, even on a dead straight road with no traffic. With traffic and an undulating road you can't do it.

Three, the tolerance exists because the police know in their heart of hearts that there is much, much more to road safety than a number. Travelling at 100 kmh does not make you "safe'' any more than driving at 108 kmh makes you "unsafe''. There are so many other factors at play: the skill of the driver, attention and distraction, conditions, the road, the vehicle, the level of traffic, the time of day, etc etc. 

So a good cop will let a driver doing 106 kmh on a dual carriageway in good conditions who is not driving erratically sail on by, and concentrate instead on some idiot doing aggressive passing on blind corners who might not even be breaking the posted speed limit. 

Removing the tolerance takes away the cop's discretion and forces him or her to ticket the good driver, whose chances of causing or being involved in an accident were practically nil. Driver is furious, cop wastes everyone's time, and the Government makes another $80.

I don't believe that driving at 100 kmh instead of 105 kmh will save lives or reduce accidents and I don't believe the police believe it either. It's just much easier to sit in a car and stick a radar gun out the window than it is to cruise the highways looking for examples of bad driving.

Enforcing such a slim tolerance will almost certainly result in massive traffic queues, however, as motorists who realise they cannot stick so closely to the limit drop back to 80 or 90 kmh, which will in turn lead to impatient drivers doing stupid things in a bid to get past the driver who's trying to be extra "safe'' by driving very slowly. 

I've no doubt that additional police presence on the roads, and additional media and attendant publicity reduces poor driving and therefore accidents. And I'm all for that.

The problem is, there is so little independent research on traffic safety that is undertaken outside of the police and the Ministry of Transport, who of course are wedded to their perspective. The late road safety campaigner John Bailey, who died in 2005, used to crunch the numbers and point out uncomfortable truths about drink-driving and "speeding''.

Bailey often argued the police should target recividist drink-drivers and those who drove at recklessly high speeds rather than the average motorist. The police therefore didn't like him much, and since his passing there has been almost no independent thought on the subject. 

Indeed, even to question the police approach is tantamount to being "pro-speeding'' or "pro drink-driving''. 

I'm neither. I'm just saying simplistic, numbers-driven campaigns such as this target the wrong people and do nothing to make the roads safer. 

This summer, I'd rather drive knowing the police were looking out for stupid, irresponsible, careless or reckless drivers pulling insane passing moves, tailgating, ignoring the two-second rule, not indicating, and driving too fast for the conditions.

Instead, I'll be looking out for the police car parked at the side of the motorway, clocking up instant fines for sober, responsible drivers in safe, late-model cars ticking along the triple-lane causeway at 105 kmh. 

It doesn't make any sense.

The Press