Mysterious A470 bridge that is baffled drivers for 13 years lastly uncovered
Those who’ve driven along the A470 will have been dumbfounded by the strange structure — but now one person has figured out what the net-like bridge is actually used for
For 13 years, motorists driving through south Wales have been baffled by an peculiar structure overhead.
Looking like a badminton net strung across a 7.3-metre stretch of the A470 in Gwynedd, it seemed to serve no obvious purpose other than grabbing drivers’ curiosity.
The structure went up in 2012 between Dolgellau and Cross Foxes. It was part of a series of environmental measures brought in during a £7.3m upgrade scheme on the A470, undertaken by civil engineering firm Alun Griffiths.
Fed up with not knowing the reason why the structure was there, a Barmouth local turned to social media hunting for explanations. “Every time I drive that way, I wonder what it is,” she confessed.
She found out it was actually a bat bridge — and not, as some quipped, built for “fishing at high tide”. The installation was designed to compensate for the loss of woodland within the Meirionnydd Oakwoods.
Its aim was to encourage bats to fly at higher altitudes, thus cutting down crashes with vehicles. Since bats typically follow hedgerows and woodland boundaries, their removal for road schemes was thought to be leaving the animals confused, according to Wales Online.
The theory was that bats, relying on sonar navigation, would recognise these “bridges” as linear features similar to the previous hedgerows. Nevertheless, they weren’t cheap: a Highways Agency assessment of a bat bridge crossing a Cornwall bypass showed they cost more than £27,000 per flying mammal.
When the A470 bat bridge was built, it became the first road in Wales to comply with the EU Habitats Directive requirements. The project also included additional bat mitigation measures such as lighting and oversized 2.7-metre-diameter culverts beneath the carriageway.
One of these culverts featured a dormouse “rope bridge”, designed to help these adorable rodents safely cross under the road. This was implemented following habitat surveys conducted nine years earlier, which found potential signs of hazel dormice in the nearby woodland — a species protected by European law.
Other measures taken included otter ledges and ramps, as well as protective steps for a birch tree known to be home to Welsh Clearwing moths. Rare lichen samples were also moved to new locations.
Despite these admirable efforts, and the subsequent discovery of breeding dormice in the area, the bat bridges raised two significant issues. Firstly, local residents were puzzled, as no one had actually seen bats near the road.
However, this doesn’t necessarily mean they weren’t there — the Meirionnydd Oakwoods are recognised as a Special Area of Conservation (SAC) for bats. Greater Horseshoe Bats — the most endangered bat species in Britain — along with six other types live in the area, using the tree canopy for shelter while hunting insects that thrive in the damp woodlands.
The second worry turned out to be far more problematic. Wildlife experts found that, despite early hopes, the bridges simply didn’t work.
Rather than confusing them for trees, bats kept flying at perilous heights above bustling roads, frequently with deadly results. Using bat detectors and nocturnal video monitoring, academics from Leeds University witnessed bats essentially dismissing the bridges, maintaining their usual flight routes instead.
Cambridge University’s Conservation Science Group declared the bridges were “based on faith and not on science”. More than £2m has been ploughed into building 15 bat bridges across Britain, with one in five positioned in Gwynedd.
Besides the A470 bat bridge close to Dolgellau, another was erected on the A487 bypass at Groeslon, near Caernarfon, in 2010. This route cuts through the Glynllifon SAC, which houses a lesser horseshoe bat colony.
Wales’ first bat bridge was erected on the A497 between Pwllheli and Criccieth during the road’s £5m improvement in 2006, intended to help six bat species in the area. Twelve months afterwards, two further bridges were installed along the A465 near Abergavenny to substitute demolished structures.
For the latest breaking news and stories from across the globe from the Daily Star, sign up for our newsletters.
