From the BBC:
6 January 2015 Last updated at 07:37 GMT
The project in Abertillery is part of a bid to cut the number being killed by cars in south Wales.
Co-ordinated by the Gwent Wildlife Trust, the new ledge at Pant Du is part of a wider scheme to identify areas where otter deaths can be reduced.
About 700 otters have been killed in south Wales in recent years.
“Otters travel widely throughout Gwent but they prefer to run along the riverbank rather than swim,” explained the trust’s conservation officer Sorrel Jones.
With cleaner rivers and growing fish stocks in the once polluted waters of former industrial Welsh valleys, the car is now one of the biggest threats to the mammals – especially at night when otters are most active.
“Ledges like this give them a safe alternative route, away from traffic,” added Mr Jones.
See also here.
Dead otter in Twente, the Netherlands: here.