Highways England is looking into ways of reducing the cost of building a canopy over roads, to protect the environment from harmful vehicle pollution.
The move is part of a new strategy to reduce the impact of Britain’s roads on the environment.
The road authority said it had identified a “cantilever barrier” or “canopy” – a tunnel-like structure designed to prevent vehicle emissions, which might be a possible solution.
With the air quality benefits of the intervention yet to be fully understood, it said it was now working with the Dutch Roads Authority to measure air quality around an existing cantilever barrier on its network.
The government is under mounting pressure to reduce pollution from road emissions and has committed £100M to improving air quality on Britain’s road network to 2021 as part of its Road Investment Strategy.
Currently diesel heavy goods vehicles, diesel cars and vans together contribute to 77% of the NO2 close to motorways.
The new strategy includes 10 pilot studies which Highways England has been carrying out from 2015 to 2018.
One study builds on previously trialled paint that ‘eats’ nitrogen oxides (NOx). In 2015 it trialled an air quality barrier on the M62 in the north of England. The 100m long barrier made of wood was intially 4m high but raised to 6m in early 2016. It then progressed to incorporating an “innovative” material with the potential to clean air.
It is now testing a 3m high fence coated in an “innovative mineral polymer material”, which has the ability to absorb nitrogen dioxide.
A Highways England spokesperson said: “The best solution to accommodating the extra traffic on our roads, without negatively impacting on air quality, is cleaner low-emission vehicles.
“In the meantime we are investing £100M to test new ideas including less-polluting fuels and road barriers which can absorb harmful emissions.”
Aecom managing director - highways & bridges Paul McCormick welcomed the push for new innovations, but questioned the how much of the road network could be impacted with the potential structures, and the cost and challenges to maintain the structures.
“It sounds like an interesting trial, but I’m not sure how much of the network it could cover,” he said.
“There’s a huge operational and maintenance aspect to it. If it was built out of solid concrete then that would be fine, but the cost would be horrific. If the structure is fabric-based, what happens with snow, wind and rain? Who is going to repair it? If it gets ripped does someone have to climb over a live highway? Do you have to close the road? Who is going to pay for the maintenance? Would we be putting people’s lives at risk to maintain it?
“It’s obviously good to push innovation and it’s great they’re trying to do something about it, but perhaps the £100M could be used to carry out schemes that might bring the date for less polluting cars forward.”