Cutting speed limits on residential streets could lead to an increase in road casualties, MSPs have been told.
Independent road safety researcher Eric Bridgestock insisted cyclists and pedestrians could be “lulled into a false sense of security” by a lower speed limit.
Green MSP Mark Ruskell wants to change the law to reduce the speed limit in residential streets and built-up areas, and has introduced a Member’s Bill at Holyrood.
But the Scottish Parliament’s Connectivity Committee was told there is no evidence such a move would improve road safety or have a significant impact on vehicle emissions.
Speaking about the Bill, Mr Bridgestock said: “There’s no evidence at all it makes anything safer, from a casualty point of view, in fact it makes this worse for the reason that people are lulled into a false sense of security on the road they are walking on.
“The whole thrust of the 20mph approach is to encourage people to feel safer whether they are walking or cycling or whatever. The more you encourage people to feel safer the less care they take, and it is evidenced in any 20pmh zone I have driven through, certainly St Albans where I live, that people wander across the road, there are pelican crossings but they wander into the road without even looking because they have been encouraged to feel safer.
“And the evidence seems to be that the casualties go up, Manchester two years ago cancelled the next stage of their 20mph roll-out because the casualty reductions in the 20mph zones were less than those in the remaining 30mph zones.”
Martin Reid, policy director for Scotland at the Road Haulage Association (RHA), said: “We’ve had a look at this and we can’t find any evidence to say there is a massive difference in terms of the emissions.
The RHA, together with other motoring and transport groups, complained about the “blanket” nature of the proposals.
They also raised concerns many motorists simply will not comply with the lower speed limit
Neil Greig, policy and research director at IAM RoadSmart, said: “Our issue is we think it’s too broad- brush, if you have an issue with a street and want to change behaviour you have to change the look and feel of the street.
“20mph without changing the character of the road doesn’t really change driver behaviour.”
A recent survey found 81% of motorists drive too fast in 20mph zones, with Mr Greig stating there is a “huge compliance issue”.
He also told the committee that “it’s not making much difference in terms of safety because these roads were often safe before”.
He said: “If you wanted to change the number of people killed on our roads you would target rural roads for example, very few people get killed as pedestrians and cyclists in our towns and cities.
“It’s very difficult to pick out any real safety benefits if that is the key thing you’re looking for.
“Also there are studies showing the reductions in speed are there, one or two miles per hour, coming down a little bit, often imperceptible, often unnoticed by the locals.”
Scottish Taxi Federation chairman Tony Kenmuir said: “Speaking for just over 23,000 public hire taxi drivers in Scotland, I haven’t had a single response in favour of the Bill.
“We’re generally in support of 20mph speed limits where it is appropriate but the feeling is the blanket approach is likely to cause a lack of compliance.”
Mr Ruskell said: “Of the 6,500 responses to the committee’s call for views, two-thirds say they support a safer limit, with majority support across local authorities, transport operators, businesses, campaign groups, community councils and individuals.
“My Bill aims to reduce injuries and prevent deaths on our streets. I look forward to giving evidence to the committee myself in the coming weeks.”
Research by the Glasgow Centre for Population Health estimates reducing the speed limit could cut casualties by between 145 and 755 a year.
This includes a reduction in fatalities of between one and five.
Separate research by transport organisation TRL concluded “accident frequency falls by roughly 6% for every 1mph reduction in mean speed for urban roads with low average speeds and by about 4% for urban roads with medium speeds”.