Highways Agency

• Safer Roads

Use of Concrete Barriers on the Highways Agency’s Motorways in England – June 2006

The Highways Agency is installing concrete barriers in the central reserves on motorways as and when existing systems reach the end of their useful life.

The Highways Agency & Safety

The Highways Agency continuously aims to improve safety and congestion. We aim to improve safety to both our road users and also to the workforce, as well as reduce maintenance related congestion. The use of high containment concrete barriers in the central reserve on heavily used motorways is one initiative that helps meet these aims.

Safety barriers and their purpose

Safety barriers are used to minimise the risk to vehicle occupants from collisions with roadside hazards. The need for a barrier will depend on the type of road, traffic speed and traffic volume and also the form of any roadside hazard. The main purpose of barriers in the central reservation of motorways or dual carriageways is to retain vehicles on the carriageway and reduce the risk of collision with vehicles on the opposite carriageway. 

The benefits of concrete barriers

High containment concrete barriers improve safety and reduce incident related congestion by: 

• Reducing the likelihood of a vehicle crossing the central reserve and reaching the opposite carriageway (by increasing the containment from normal to high)
• Reducing the maintenance required to a barrier following a vehicle strike, thereby reducing the risk to the workforce and work related congestion (concrete barriers require only minimal repair in most cases compared to traditional steel barriers if struck).
• Being virtually maintenance free and having a life of 50 years compared to 25 years for traditional metal barriers.

The Highways Agency’s policy on barrier types

With effect from January 2005 and based primarily on safety grounds, the Agency’s policy is that all new motorway schemes are to use high containment concrete barriers in the central reserve. All existing motorways will introduce concrete barriers into the central reserve as part of ongoing upgrades and through replacement as and when these systems have reached the end of their useful life. This change of policy applies only to barriers in the central reserve of high speed roads and not to verge side barriers. Other routes will continue to use steel barriers.

Concrete barriers have been installed on a number of roads already, such as M11 Junction 8-9 and M62 J37-38. 

The Dutch Step Concrete Barrier

The Highways Agency is implementing its barrier policy using the high containment Dutch Step concrete barrier. This system has a unique stepped profile that has been shown through testing and computer simulation to help in reducing the injury to occupants of small cars compared to flat fronted rigid barriers. The Step is designed to allow minor vehicle contact to be limited to the base of the barrier and the vehicle tyres. Such slight impact will, in most cases, allow the vehicle to continue undamaged on its journey. This system has also been extensively tested to the European Safety barrier standard EN1317 and shown to contain all vehicles, including 4x4, pick up trucks and light vans up to 13.5 tonnes - including most buses and coaches.

At present there is no European test to look at the effect of motorcyclists and barriers. However, some research has been carried out and this indicates that concrete offers a safer option compared to post and rail systems. 

Further Information

To find out more information on this subject please refer to Interim Advice Note, IAN 60 for an overview of the implementation policy http://www.standardsforhighways.co.uk/ians/pdfs/ian60.pdf

Or visit Britpave website for an overview of the technical requirements on installing concrete barriers, www.britpave.org.uk Work in Progress on the M62: The slip form process used for constructing the Dutch Step Barrier Work in Progress on the M62: finished High Containment Dutch Step concrete barrier