Highways England has given details of a tunnel
constructed under a busy road without any interruption to traffic
as part of a pioneering scheme to cut pollution.
The trial project involves installing underground drainage
pipes – tunnelled under the A38 at Dean Burn in Devon – and a
filtration pond filled with engineered soil to trap oil and metal
residue that are carried in the water running off the busy
road.
The area is particularly important because right next to the road
sits Potter’s Wood, a protected Site of Special Scientific
Interest (SSSI), and as well as improving water quality, earth
excavated from the pond and tunnel is being used to create bug
hotels, butterfly scrapes and bee banks to benefit biodiversity.
The scheme, enabled by Highways England’s Environmental
Designated Funds, has been designed by contractors Kier and
delivered by South West Highways, and if successful, the system
could be rolled out at other locations around the country’s major
A roads and motorways.
Highways England Project Manager Michelle Reed said:
We’re very excited to be trialling this new and innovative
environmental system and if it’s successful we could be rolling
it out across the country.
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.
Michelle added:
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 Dean Burn scheme started in July and with KJ Thulborn
undertaking landscaping and environment features, the work is
scheduled to be completed by 31 October.
Highways England is committed to addressing the impacts of its
strategic road network, and last month work started on grasslands
schemes on the A1 and A64 in Yorkshire, sowing the seeds for
species of pollinators to flourish on the roadsides.
This follows the success of a similar scheme on the A38 in Devon
which has just been awarded the Ciria’s BIG Biodiversity
Challenge Pollinator Award for 2019.
A number of other Designated Funds projects are being undertaken
elsewhere in the South West, including:
- a scheme to restore a section of the Cotswold Canal near M5
Junction 13 in Gloucestershire
- a reedbed filtration scheme at Stover Country Park in Devon
- a cultural heritage project to enhance the historic Stoke
Park landscape alongside the M32 in Bristol
- cycling, habitat and heritage projects alongside the A30 in
Cornwall
- cycle path initiatives around the new M49 junction scheme at
Avonmouth
The Government allocated £675 million of funds to Highways
England over a five-year spending period covering 2015 to 2020 –
a series of ring-fenced funds designated to address a range of
issues including Environment, Cycling, Safety and Integration,
Air Quality and Innovation.
The Highways England Environmental Designated Fund of £225m has
been set up to improve the environmental performance of the
Strategic Road Network. It is to be used for projects that are
‘beyond business as usual’ which will help achieve benefits for
one, or preferably a combination of areas including: cultural
heritage, biodiversity, landscape, flooding and water quality,
carbon emissions and noise pollution.
