In the daily battle between motor vehicles and pedestrians for supremacy on the streets of our towns and cities it’s pretty obvious the car has won the fight hands down over those who prefer to walk or cycle. Over the years, town planners have provided motorists with an unfair advantage by introducing complex town centre traffic schemes, often making it difficult for pedestrians to cross roads at busy intersections and turning the daily commute for cyclists into a life-threatening duel with 40-ton trucks.

While traffic has to be kept moving on main roads passing through urban environments, road safety campaigners are hailing what they describe as a ‘cultural shift’ in the way local authorities are currently reversing decades of policy that favoured the movement of vehicles over the safety of pedestrians and cyclists on minor and unclassified roads. Dozens of local authorities across the UK are currently responding to government backing and are set to introduce even more 20mph speed limits in residential and commercial areas in an attempt to reduce the number of serious road casualties.

It’s well known that excessive speeds increase the chance of pedestrians – especially children – being fatally injured in a collision with a motor vehicle. Figures released by the Royal Society for the Prevention of Accidents (RoSPA) show that at 20mph there is a 2.5 per cent chance of a pedestrian being killed in a collision compared to a 20 per cent chance if the vehicle is travelling at 30mph. Lower speed limits have already received the backing of the European Parliament and the government has already cleared the way for local authorities to implement the lower 20mph limit without further consultation wherever it’s deemed necessary.

One of the first cities in the UK to impose a large number of 20mph limits was Portsmouth where the lower limit was introduced to about 94 per cent of the city’s roads previously restricted to 30mph. On roads where the average speed was recorded to be between 21mph and 24mph before the limit was lowered, the overall average dropped to 18.5mph. Although the average speed on Portsmouth’s restricted streets was reduced, it was found that the £500,000 scheme failed to significantly reduce the amount of accidents on the city’s roads. In fact, according to a report in the ‘Daily Telegraph’, the number of people killed or seriously injured on Portsmouth’s roads after the limit was lowered to 20mph actually went up, not down.

Research has proven that lower speed limits are more appropriate on roads where average speeds are already low and the lay-out provides a clear impression for motorists that a 20mph speed limit is appropriate, such as past a school or a parade of shops. On some roads, a lower speed limit can attract more business when pedestrians don’t feel threatened by fast moving traffic, and can also be the catalyst required to regenerate a deprived area. Although, according to RoSPA, only a small reduction in overall speed is recorded on roads where the lower limit has been imposed by installing repeater signs along a route, rather creating specially devised 20mph zones. Extra sign clutter can also be confusing to the motorist, especially as councils across the UK are currently pledging to reduce unnecessary road signage, whereas the lower limit in specially designated 20mph zones featuring traffic calming devices, such as speed bumps or chicanes, tend to be self-enforcing.

The use of traffic calming devices continues to raise a number of concerns among many motorists who claim that road humps and speed cushions can damage their cars’ steering and promote premature tyre wear. To counter these claims, the Transport Road Laboratory (TRL) and Millbrook carried out a number of trials that included testing vehicles negotiating various speed calming devices and creating computer models of vehicles and their occupants. Contrary to popular belief, it was discovered that the tests didn’t show any vehicle damage from the humps or any significant or permanent changes to the test vehicle’s suspension systems if the speed limit was adhered to.

The report also stated that the levels of discomfort caused by the humps were generally acceptable if the vehicle traversed the humps at the appropriate speed (15-20mph) and that the forces on the occupants’ spines were smaller than what could typically cause an injury. What the report failed to mention was that owners of cars with low ground clearances, such as classic sports cars, need to take particular care when traversing speed humps so as not to cause damage to front spoilers or low-slung exhaust systems, let alone the occupants’ backs! There is also a rising cause for concern from residents on controlled routes who have reported fatigue cracks appearing in the fabric of their properties, caused by the vibrations from vehicles negotiating traffic calming devices.

Another area for concern over the proposed expansion of 20mph zones is the effect of traffic calming devices on the response times for emergency vehicles, such as fire engines and ambulances. TRL research also looked at the average response time for a fire tender running over different types of traffic calming devices in a Surrey housing estate and came to the conclusion that responses times were affected, although the vehicle’s average speed was proved to be higher over speed cushions and lower over flat top humps.

Whenever local authorities plan future 20mph zones, it’s vital that the local community is consulted along with the emergency services to identify any issues with on-street parking and access before traffic calming devices are installed. In principal, reducing the speed limit to 20mph in residential areas is a good idea – it will save lives and stop side roads being used as rat-runs – provided the reduced limit is enforced properly and non-destructive traffic calming devices are installed.