UK’s Highway Safety is Set in Concrete

Spending cut-backs have become part of the every day norm for the UK Government as it struggles to overcome to the global economic recession that has hit it so hard. But the tough times have also seen some glimmers of hope – especially on the roads, where projects are being brought forward to stimulate the economy. One major benefactor, beyond the workforce, is safety.

In 2005, the government said it would phase out the aging and more dangerous existing steel barriers seen on motorways and replace them instead with new concrete replacements. In 2009 alone, £400m of accelerated works will be done by the Department of Transport – and this will include its important safety barrier project.

But spending this money up front is more than just good for the economy. The savings in health spending can also be proved alongside existing road death figures and the overall long-term cost benefits of concrete step barrier (CSBs) also speak for themselves.

Road’s safety net

Work to replace steel central reservation barriers with CSBs was carried out last month on two major UK motorways: the M1 – a £16.4m project between junctions 32 and 35a – and the M62 in West Yorkshire. This £27.9m safety improvement scheme for the M62, carried out by Balfour Beatty and supervised by CarillonWSP forms part of the Department for Transport’s (DfT) £700m fiscal stimulus package – which was due to be rolled out in 2010/2011 but has been brought forward in a bid to stimulate the economy.

Now, as existing steel barriers meet the end of their 20-year life, concrete barrier replacements are being phased in. This became policy by the Highways Agency in 2005 when its Interim Advice Note 60/05 (IAN 60/05) called for the use of rigid concrete safety barriers for motorway central reserves where annual average daily traffic (AADT) exceeds 25,000 vehicles a day.

“It will apply wherever suitable to new road schemes, existing road improvement schemes such as motorway widening or where existing barriers in the central reserve are due for replacement,” the Highways Agency said.

According to the Highways Agency there are more than 400 crossover accidents where vehicles break through the central reservation barrier each year in the UK and about 40 deaths (at a cost of £1m a fatality). A report by the Transport Research Laboratory showed that 70% of these accidents could be avoided if concrete barriers were implemented.

The results, from a series of computer models developed by Arup for transport infrastructure group Britpave, offered a simulated view of the impact from a range of vehicles hitting the barrier. It found the stepped design could reduce the effect of impact on passengers. These findings were confirmed later by the Motor Industry Research Association.

As well as being robust and more motorbike friendly, the concrete barriers also overcome issues with steel barriers, which are often bordered by soft earth or grass which can cause drivers to lose control when they come into contact with their vehicle. CSBs are supported by a base of concrete and tarmac, which offers more contact. Concrete is also non-combustible (it is classified an A1 fire resistant material under EN 13501-1), which makes it an effective barrier to the spread of fire in the event of an accident.

Further endorsement for the CSB came from the Parliamentary Under-Secretary of State for Transport Jim Fitzpatrick after a lorry crashed through the central reservation on the M40 in May 2007 and killed three people in a seven-vehicle crossover accident.

On impact with a concrete barrier, any vehicle up to 13.5t in weight, which includes most buses, coaches and 4x4s, will be contained and redirected back to the highway. Steel barriers, on the other hand, are only able to contain a 1.5t car, such as a Ford Focus.

According to Britpave the barriers also reduce a driver’s ability to ‘rubberneck’ incidents in the opposite carriageway as the headlamp glare, especially when it is raining, is blocked by the concrete barrier.

Proving its price

It is not only lives that will be saved in the UK when new concrete step barriers are installed, the longevity of concrete also brings the long-term costs down. Introducing the barriers can cost less in regards to land purchase than introducing steel barriers, which require more outlay of land. At 900mm high and with an overall base width of 542mm the barriers are narrower than two parallel rows of steel fencing – yet as they are incredibly robust a single barrier is more than sufficient for both sides of the motorway.

Although they are narrower than steel barriers, a further advantage is that concrete barriers will last for about double the time – about 50 years – and unlike steel barriers will require no repairs or maintenance. This significantly reduces the cost, and improves the flow of traffic by reducing the need for closure of lanes. The fact that there are 100 repairs carried out on steel barriers each month on the M25 alone (according to Britpave) puts the potential time and cost saving into perspective.

Therefore, despite it being 30% more expensive to install concrete barriers (as revealed in IAN 06/05), when the whole-life cost was assessed it was shown that the actual figure was more like 0.2% – once the reduced maintenance and traffic management costs had been taken into consideration.

Sustainable solution

In addition to safer roads, CSBs also offer a sustainable solution – the UK produces the majority of concrete that it requires itself and recycled aggregates can be also used in the construction of CSBs.

Its environmental benefits don’t stop there. According to Britpave’s ‘Sustainability Benefits of Concrete Step Barrier’ report, “the average embodied quantity of CO² in a metre of surface-mounted CSB can be as low as 19% of a similarly performing steel solution over a 50-year period.”

Despite the phasing-in rate being questioned by Robert Goodwill, MP for Scarborough and Whitby in 2007 (who questioned why less than 100km of existing barriers on a total 3,240km of motorway had been replaced with concrete barriers?), the CSBs continue to be phased in during road maintenance and widening when the steel barriers come to the end of their life.

So far new CSBs have been installed on highways across the UK, including the M62, M18, M180, M1, M4, M5, M6, A12, A27, A1 and the A55. To date there have been no crossover accidents where a CSB is in the central reservation, and the deployment of this successful product is set to continue.

“The concrete barrier saves lives, money and journey time, and protects the environment by using lean construction techniques and 100% recyclable materials. It is a truly holistic sustainable solution which encompasses social, environmental and economic facets,” concludes David Jones, director of Britpave.