Speed limits that are impractically low tend to be ignored, leading to an increase in road deaths, according to studies quoted in the Times newspaper in the UK.
English Department for Transport research showed that nearly nine out of ten drivers exceeded the limit in 20mph zones. There was a corresponding increase in deaths and injuries on the slowest roads.
The study, which used automatic traffic counters to measure the speeds of 15.3 million cars, showed that 86% of vehicles exceeded the speed limit on 20mph (32km/h) roads.
Clive Matthew Wilson, editor of the car review website dogandlemon.com, is not surprised by the findings:
“American research shows that motorists tend to drive at a speed that feels right. If the speed limit is set unreasonably low, drivers tend to ignore it.”
“Most drivers understand that the roads beside schools and old folks' homes are dangerous to pedestrians. If the low speed areas are confined to areas of known high risk, motorists tend to obey the law. If the lower speed limits are blindly applied everywhere, drivers tend to ignore the law.”
A 2017 review of 20mph limits published by the Royal Society for the Prevention of Accidents (RoSPA) supported lower speed limits in urban areas, but concluded that the lower limits are far more effective when they are accompanied by traffic calming measures:
“...traffic calming slows vehicles down to speeds below the limit, and in this way the zone becomes ‘self-enforcing’. Speed humps, chicanes, road narrowing, planting and other measures can be introduced to both physically and visually reinforce the nature of the road.”
Matthew-Wilson agrees, adding that the best way to protect pedestrians and cyclists is to physically separate them from cars.
“Cars have airbags. Pedestrians and bikes don’t. It’s vital that our city planners keep cars separate from people walking and riding. It’s also important that planners recognise that bikes may pose a threat to pedestrians."
“Roading engineers tend to see pedestrians as a nuisance, so they position pedestrian crossings in places that don’t fit the needs of people on foot. As a result, pedestrians cross in high risk places and may get hit.”
“Roading engineers also fail to grasp how dangerous our roads can be for people with limited mobility and poor eyesight. Regardless of the speed of the road, pedestrian crossings need to be convenient, they need to give pedestrians ample time to cross and cars must stop entirely while crossings are in use.”
Matthew-Wilson says intelligent road design should be a higher priority than unrealistic speed limits.
“The problem with the whole ‘down with speed’ campaign is that the highest risk motorists tend to ignore speed limits.”
Matthew-Wilson gave the example of a fatal accident in central Auckland on December 22, 2017, in which a drunk and speeding motorist ran a red light and killed a taxi driver.
“Since drunk and drugged drivers rarely obey traffic laws, would a lower speed limit have prevented this incident? I doubt it. A restriction on alcohol sales in the area might have helped, but restrictions on alcohol sales rarely get mentioned by road safety planners.”
