Are motorways in England Suitable For Proposed 80mph Speed Limit?

A report from the Road Safety Foundation examines the suitability of England’s motorway infrastructure for Government proposed speed limit increase.

Go straight to download or read the TrafficSafe review below:

In response to the UK Government’s proposal to raise the speed limit on the nation’s motorway network from 70 to 80mph (112.6 to 129kph) under certain conditions, the Road Safety Foundation has completed a comprehensive study of accident and traffic volume statistics as well as its own records and conducted a survey of the 1870 miles (3009 km) of English motorways to consider whether the proposals are feasible.

The Government proposal is based on arguments that both road and vehicle technology improvements in the last 35 years have led to safer conditions for road users justifying an increase in the limit which would bring economic benefits resulting from reduced travel times.

The Road Safety Foundation doesn’t deny that such technological improvements have resulted in road safety benefits but points out the changing patterns of transport dynamics during that time and also the types of accidents that are now resulting in fatalities and serious injuries on motorways.

Referring to the “safe system” approach for reducing serious road incidents involving driver behaviour, vehicle design and infrastructure design, the improvements made in vehicle occupant protection are generally only effective in frontal impacts of up to 40mph (64kph) and 30mph (48kph), way below normal motorway speeds. It is therefore down to infrastructure design to provide additional protection above those speeds.

With the enormous amount of statistics available to the Foundation, it was straightforward to conclude with a high degree of certainty that the majority of road deaths fall into four broad categories, being head-on frontal impacts, side impacts at intersections, colliding with roadside objects and accidents involving vulnerable road users such as cyclists of pedestrians.

The majority of these kind of accidents are eliminated or their impact reduced on motorways through design changes implemented across the network in the last 40 years including crash barriers between carriageways, prohibition of vulnerable road users from the motorway system, run-off protection, crash barrier protection for roadside objects and the use of split-level junctions with slip-ways and roundabouts.

As protection has increased in this way, the types of accidents which are claiming lives have also been changing and this is largely associated with the increased traffic volume. In this respect, the Road Safety Foundation identifies two accident categories which account for 43% of all serious motorway collisions:

* Run-off accidents

Run-off protection has been put in place across parts of the network but as much as 50% of the network falls below adequate standards. The Road Safety Foundation points out with traffic volume approaching a million vehicles a week in some sections, even such an isolated combination of circumstances representing a one in 10 million chance can occur once every three months.

* Rear-end collisions (or shunts)

Shunting is a phenomenon strongly associated with congested traffic conditions where flow speeds can change abruptly and a lapse of concentration can easily result in a rear end collision. As traffic volume continues to increase, the Road Safety Foundation has shown that the risk of shunting incidents increases exponentially.

A reduction of such shunting incidents can be achieved with a combination of high visibility variable messages signs, recessed protected refuge areas, variable speed limits and strict enforcement such as currently only exist on the western M25 section and part of the M42 motorway south of Birmingham.

In conclusion, the Road Safety Foundation recommends improved run-off protection in current sub-standard and high risk areas of the network and more widespread use of VMS and enforced variable speed limit technology across England’s motorway system.

Download the Road Safety Foundation report on the 80mph speed limit proposal.

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