Can changing road speed limits work both ways?

Can changing road speed limits work both ways?

by Liam Kerr
article from Thursday 15, June, 2017

BACK IN MARCH, I wrote about the folly of the plans to cut the national speed limit to 20 mph in all residential zones as it would not improve road safety and nor would it lead to an uptake in cycling. It would be far more productive were we to design the speed limit around conditions, appropriateness for city zones, times and the actual road.

The same analysis applies at the other end.

Current UK speed limits were set in 1965, but since then driver training has improved dramatically. With the driving test set to be toughened again in December 2017, there have been remarkable improvements in road conditions, car technology and safety. All of this has contributed to a more than 75 per cent reduction in the number of people killed on British roads.

Congestion on the English major road network costs around £2 billion every year. By 2025 Britain will have wasted £22bn from being stuck in traffic travelling to work. Cutting congestion and/or speeding up traffic offers significant economic benefits.

Our fastest roads, motorways, are also statistically the safest.

Yet IAMRoadsmart suggest that on uncongested motorways, 57% of car drivers exceed 70mph and 20% exceed 80mph. The former Secretary of State for Transport, Philip Hammond, has argued that if 50% cent of the population are routinely breaking the law, “policing by consent” is undermined and the law needs reviewed.

Britain’s speed limits are lower than many other countries in Europe.

In France, the speed limit depends on weather conditions, reducing from ~56 mph on “A” roads, dual carriageways ~70 mph, motorways ~81mph – down to ~50mph, ~63mph, ~70mph in the wet.

On about 60 per cent of the German autobahn there is no speed limit, although the advisory limit is 81mph. German motorists’ organisation, ADAC, spokesman Andreas Hölzel stated that: “If you look at international comparisons, Germany – with no generalised speed limit - performs just as well on safety”.

In the Netherlands, the speed limit on motorways was increased to 80 mph in 2012 after a comprehensive review of motorway capacity, congestion and safety suggested that since cars and roads were more safely engineered, the old speed limit was anachronistic. Motorists report shorter journey times, greater enjoyment and lower congestion.

Surely it is now time to have a discussion about speed limits, including an 80mph limit on motorways. Looking at the facts, and taking account of human behaviour, there is a debate to be had about how we can improve safety and ease congestion.

The UK Government has made preliminary investigations into such a move. In April 2015, new HGV’s-over-7.5 tonnes limits came in on single carriageways (50mph, up from 40) and dual carriageways (60mph, up from 50) in England and Wales, to save hauliers an estimated £11 million a year and "reduce congestion…”.

In 2016, the UK Government announced new plans to raise speed limits at motorway and trunk-road roadworks from the current maximum of 50mph, to cut congestion. Highways England are running a trial on a four-mile stretch of roadworks on the M1 between junction 34 and 35a near Sheffield in South Yorkshire, with a 60mph limit.

But does increased speed reduce safety?

Not according to Ed King, the President of the AA, regarding the HGV change who said in 2014: "… quite often trucks doing 40mph on rural roads… causes congestion but actually causes added danger. If the truck is doing 50mph… the driver will be quite content to stick behind it rather than try to overtake”. Evidence suggests that, as a result of increasing these limits, accidents caused by overtaking were reduced by between 10% and 36%.

Not according to a two-year study by the Danish Road Directorate which states that a 2011 increase in speed limits on rural roads decreased the number of road accidents, because the difference between fastest and slowest cars was reduced, resulting in less overtaking. “If there is a large difference between speeds, then more people will attempt to overtake, so the more homogeneous we can get the speeds on the two-lane roads, the safer they will become,” Vejdirektoratet spokesperson Rene Juhl Hollen commented.

On motorways, the Danes increased the limit nearly a decade ago from 68mph to 81mph. Road traffic Accident fatalities have decreased.

At the heart of this is that 80mph is a safe speed. As Edmund King said recently: “80 mph in a modern car in good weather at a safe distance from the car in front is perfectly safe. Driving at 50mph tailgating the car in front is not”.

One concern might be how to prevent the unofficial 80mph limit today becoming tomorrow’s unofficial 90mph limit?

Firstly, the Danish study above showed that slower drivers became faster with the new higher speed limit, closer to that limit, but the fastest 15% of drivers only drove 1km/h faster than before.

Referring to the Dutch example, IAMRoadsmart report that “motorists appear to have taken the new ‘130kph means 130kph’ policy to heart; there are few, if any, signs of speeding above the limit…”

Research suggests that drivers use clues from the environment around them to judge the appropriate speed. Such limit should be set at a credible level that drivers understand and respect matching the road environment and conditions, which in turn will promote self-compliance and confidence in limits.

Where limits do not match the environment and/or prevailing/likely conditions, uncertainty and confusion distract from appropriate decision making. Uniformity introduces an unhealthy disrespect, especially where it makes those areas where slower speed is required less unique.

This implies variable speed limits. Certainly possible as shown on the M8 in Glasgow and overhead gantries, such as those on the M25, could presumably do the job. Part of this also means investment in more ‘smart motorways’. These demonstrably increase capac­ity and relieve con­ges­tion. They shorten journey times and ensure safety by changing the speed limit to smooth the traf­fic flow. They can also activate warning signs to alert drivers to hazards ahead, and close lanes to allow emergency vehicles through.

After the first smart motor­way (the M42) opened to traf­fic in 2006, jour­ney reli­a­bil­ity improved by 22%, acci­dents were cut by 50% and those accidents which did occur were much less severe with no reported fatal­i­ties and fewer seri­ous injuries.

People will understandably be reluctant to increase speed limits but we must have a discussion on this, guided by facts and examples, including from our European neighbours. As I argued in my piece on 20mph limits, human behaviour and environmental factors should play a part in these decisions. The motorist should no longer be treated as a cash cow, but as a key player in finding the right balance between safety and fluidity. The time to debate whether speed limits should reflect the reality of today’s modern vehicles, driving conditions and tests, or those of 50 years ago, is now.

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