Road safety should learn from human behaviour, not work against it

Road safety should learn from human behaviour, not work against it

by Liam Kerr
article from Thursday 2, March, 2017

THE SCOTTISH GREENS outlined plans recently to cut the national speed limit to 20 mph in all residential zones. Whilst I am pleased to see the Greens have temporarily given up propping-up the SNP and trying to separate Scotland from its main trading partners, I am less happy that its move towards 20 mph limits will undermine efforts to protect people.

Announcing the policy, the Green environment spokesperson Mark Ruskell, suggested this change to the law will give communities “safe streets for walking and cycling”, and directly linked the 20 mph limit with increased cycling.

Would a 20 mph blanket limit achieve this? Doubtful.

At the heart of these plans is a fundamental misunderstanding about how humans behave, and this policy – which would have profound issues with enforcement – risks numbing drivers to their surroundings and, consequently, increasing danger.

We, in the Scottish Conservatives, instead make the case for targeted safety zones. We should be focusing on imposing 20 mph zones where they are specifically needed, for example in dense residential areas and outside schools and hospitals.

The evidence on blanket 20 mph limits increasing safety is inconclusive. Some years ago the Transport Research Laboratory found that 20 mph signs produced only a small reduction in speed and, following-up in 2009, showed such limits reduced the average speed by 0.9 mph: not statistically significant.

The first area to introduce a blanket 20 mph limit was Islington. Studies of that experiment found it did successfully cut the driving speed of 85 per cent of traffic. Crucially, however, that cut was of 1 mph on average, slowing drivers down from 28 mph (in what were 30 mph zones), to 27 mph.

Furthermore, a study in York suggests 20mph limits could be increasing rather than reducing the risk of accidents, by lulling pedestrians into a false sense of security and taking less care.

It is not a stretch to argue this applies equally to drivers.

If you remove the need for people to “consciously” drive, you reduce their attention. If you impose a 20 mph limit on a straight, clear urban artery on a bright sunny day with minimal traffic, drivers glaze over; or, as happens now, with blanket prohibitions which take no account of prevailing conditions, simply ignore it.

All responsibility on the part of the individual cannot be removed. All roads are not the same; those hazards encountered in towns do not all pose the same level of risk. And not all drivers are equally reckless or safe. One size rarely fits all.

We must recognise these studies’ findings – and formulate policy on what is practical and achievable, based on human behaviour. We must treat road users as adults. Research suggests that drivers use clues from the environment around them to judge the appropriate speed. A limit is just that: a “limit”. It is not a “target”, and we should be ensuring drivers are trained to judge the appropriate speed, not delegate responsibility to an arbitrary yet mandated sign.

Similarly, where limits do not match the environment and/or prevailing/likely conditions, uncertainty and confusion are generated, distracting from appropriate decision making. Such uniformity also introduces an unhealthy disrespect for limits – especially where it makes those areas where slow speed is required less unique, with a potential attendant impact on road safety. Twenty-five or so years ago I learned to drive on, amongst others, the A701 Edinburgh to Moffat road. I recall my instructor saying “on this road, when they put a warning sign, they mean it”. Those familiar with that road will know you ignore those warning signs at your peril. The result? Appropriate speed commensurate with the signs and conditions is observed.

There would be clear issues with enforcement of a blanket 20 mph limit, given the sheer number of road users and our underfunded police service. Indeed, the greater the prospect of flouting road laws and getting away with it, the more chances some drivers will take. Phase one of the Edinburgh 20 mph policy was rolled out last year. Police road checks were called off after a week; a week in which they handed out two fines and 36 “formal warnings”.

On the contrary, a speed limit which matches the road environment promotes self-compliance and confidence in the system, removing the need for costly enforcement.

Thus, a solution, a way to increase road safety, remove decisions on adherence to road laws, and to the issue of enforcement, is targeted 20 mph zones, enforced by appropriate measures such as speed bumps. These would be determined by the those who know a community’s roads best: the people living there, key stakeholders, and the local authority, and restricted to locations and times where the need for a 20 mph zone is obvious. They should be targeted at roads that are primarily residential and on streets where pedestrian and cyclist movements are high such as around schools, shops, markets, playgrounds and other areas – or where a specific hazard requires a specific solution. There is clear evidence the risk of casualties will then be reduced.

And any 20mph zone must be self-enforcing by ensuring that signposting, features, and traffic calming measures “make sense”. Instead of imposing restrictions on all drivers to catch the careless, uncaring or simply those who realise the limit is ill-thought through, build in segregated design features for enhanced pedestrian and cycling safety.

The Greens’ impractical idea of a blanket 20 mph limit would fail to achieve its stated aims. Instead, we should create a system where drivers regulate their own behaviour, within the boundaries of speed limits which take account of the specific environment and conditions, aided by reduction measures where they really are necessary.

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