Highways England has constructed a tunnel under a busy road with minimal disruption to traffic as part of a pioneering scheme to cut pollution.
The trial project involves installing underground drainage pipes under the A38 at Dean Burn in Devon along with a filtration pond filled with engineered soil to trap oil and metal residue in the water running off the busy road.
Video released by Highways England shows how small-scale tunnelling equipment was used to dig the modified drainage channel under the A38 while vehicles travelled above unaffected.
Project manager Michelle Reed said: ‘This is the first time we have used this machinery in the South West and it’s been such a success we have completed the tunnelling ahead of schedule and only two overnight lane closures have been needed.’
The scheme is funded through the government-owned company’s designated environmental funds. Highways England said that if successful, the system could be rolled out at other locations on the strategic road network.
Potter’s Wood, a protected Site of Special Scientific Interest (SSSI), sits right next to the road. Earth excavated from the pond and tunnel is being used to create bug hotels, butterfly scrapes and bee banks to benefit biodiversity.
Ms Reed added: ‘Our Designated Funds programme was developed so that we can invest in projects beyond our traditional road build and maintenance, and this is a glowing example of how this funding can have a positive impact on people and communities.
‘The filtration system provides a physical barrier to polluted water, then chemical and biological mechanisms work in combination to break down even more pollutants. It also has the advantage of taking up far less space than other treatment systems, which makes it very cost effective.
‘When completed, this work should significantly improve the quality of water running into Dean Burn and help to support the local environment and its wildlife.’
The project has been designed by Kier and delivered by South West Highways.
