Safety: Road designs for life

Half of all road deaths in the UK take place on just 10% of the country’s main road network.

The majority of these incidents are at junctions, with roadside objects or head-on collisions, and occur just outside major towns and cities at speeds where safety equipment such as airbags and crumple zones cannot provide enough protection to the vehicle’s occupants.

It means road design has a vital role to play in reducing the number of casualties on UK roads; so much so that international best practice sees the driver, vehicle and road treated as one combined entity when it comes to protecting road users from serious harm.

It also means that targeting problem areas with a range of safety measures – often low-cost – can have a dramatic impact. For example, between 2007 and 2009, there were 12 fatal and serious crashes on the A404 between Amersham and junction 18 of the M25.

After working with the Road Safety Foundation (RSF), Buckinghamshire and Hertfordshire County Councils introduced a range of measures such as resurfacing, improved road markings, lowering the speed limit and improving crossings on a stretch where pedestrians were especially vulnerable.

These changes led to just one fatal or serious crash taking place on the six-mile stretch of road between 2010 and 2012. “The measures that worked were both low-cost and straightforward,” says Caroline Moore, senior research analyst at RSF.

“Our research shows that improving road safety is not down to just one factor, but needs to be treated as a combination of vehicle safety, driver behaviour and road design. There is an element of drivers behaving poorly, but there are also a lot of drivers who just make simple mistakes and, unfortunately, some make mistakes where there’s a tree right next to the road, which can lead to serious injuries.

“If that tree was a little further away, or had a barrier in front of it, the outcome of that crash would be very different.

“Also, was it a narrow road? Were the road markings up to scratch? These are some of the things we look at in our research. Not all countermeasures that make a significant difference have to be expensive.”

RSF is a founder member of the Euro RAP scheme, which rates the in-built safety of motorways and the A-road network outside urban centres using a five-star ranking, just as the Euro NCAP star rating system rates the in-built safety of vehicles (see page 40).

This covers all aspects of a road’s design, including surface and markings, signage, speed limits and traffic calming measures, such as pedestrian crossings and roundabouts.

“If you look at all the single-carriageway roads that aren’t medium risk or higher, you see all the same features: wide roads, paved shoulders, warning signs for junctions and T-junctions that have a merge lane,” says Moore.

The Euro RAP ratings are calculated by analysing approximately 50 attributes every 100 metres of road, using images taken either by using cars fitted with 360-degree cameras or through Google Streetview.

“All these images go to an office where a team of coders will review each of them and that data gets fed into a software system,” says Moore. “This generates star ratings for every 100m of road, but we present our results as average ratings for every three kilometres so it’s easier to read on a map.

“Generally, we say that if you improve between each star rating, you will see a 50% reduction in fatalities, and that’s based purely on how well the road is protecting the vehicle if it has a collision and how likely it is that the vehicle will have a crash.”

RSF uses its research to support its campaign to improve the safety of existing roads, as well as influence the design of new roads.

It wants all roads to gain a minimum of three stars, an ambition shared by Highways England for its 4,300 miles of motorways and major A-roads.

Highways England aims to ensure that more than 90% of travel on its network is on roads with a safety rating equivalent to three stars by 2020.

This is part of its ambition to reduce the number of people killed or seriously injured on its network by 40% by the  end of 2020, with its aim to get as close as possible to zero by 2040.

At the moment, 50% of its motorways are rated three-star with the remainder four-star; 78% of dual carriageway A-roads are three-star (four-star 20%, two star 2%); and 35% of single carriageway A-roads are three-star (two-star 62%, with less than 1% one-star).

 “While we cannot eliminate risk on our network or in the things that we do, we can recognise it, assess it correctly and take steps to manage or mitigate the dangers,” says a spokesman.

“We also aim to improve our information to road users to ensure they better understand how to use our roads, for example the signs they will see on a smart motorway and the variable speed limit signs that help manage traffic flows.”

The Transport Research Laboratory (TRL) has been instrumental in the development and introduction of ‘smart’ motorways, and has also carried out work in other areas of safe road design. This includes psychological traffic calming, which is used to slow traffic down when entering 30mph zones.

“By painting lines on the road to make it feel narrower or the turns feel sharper, you can increase the driver’s perception of risk without increasing the actual risk,” says Nick Reed, academy director at TRL.

“This encourages the driver to adopt slower speeds and that was shown to  be successful in both the simulator and in real life testing, so this is a low-cost way to reduce speeds.”

Other psychological measures include creating ‘gateways’ into villages and using different coloured road surfaces.

Reed says the development of new vehicle technologies has increased the need to focus on road and lane markings.

“There is a need now for lines to be maintained to a higher standard to enable the current generation of automated vehicles to follow those for guidance,” he says.

“I know that Highways England receives complaints from drivers of vehicles with lane guidance systems, who want  to know why they weren’t able to use their driver aid on that particular stretch of the motorway despite the fact the lines are perfectly appropriate for a human driver.”

This has led it to develop the MarkingCollector device which is able to monitor a road marking’s reflectiveness and condition.

TRL is also looking at how the information presented on motorway gantries can be presented inside a vehicle using connected vehicle technology.

“This would give the driver very specific information about their particular journey, what the current speed limit is and what lanes are appropriate for their travel,” says Reed.

While Highways England’s road network accounts for only 2% of the country’s roads, it carries a third of all national traffic, with four million people driving on it every day.

Despite this volume of traffic, Department for Transport (DfT) statistics showed the Highways England network accounted for 10% of reported casualties in 2013: 47% were on local minor roads and 43% on local major roads.

DfT figures released last month showed that country roads are the deadliest, with an average of three people dying on them every day last year.

In total, 1,040 people were killed and 9,051 seriously injured on country roads in 2014, with a third (348) of fatalities occurring on a bend.

“Sometimes we will flag up a poor performing single carriageway, and the relevant authority will say it will carry out an education campaign for motorcyclists, or it’s trying to tackle speeding with cameras, but we come from the angle that it could do more with the road design,” says Moore.