Deserted Sully Island's traffic lights to help visitors

The warning signs will shine red, yellow or green to warn about the tide

An island which has no roads or residents is being equipped with traffic lights - after visitors kept getting cut off by the tide.

Sully Island on the Vale of Glamorgan coast can be reached by foot at low tide via a rocky causeway.

But over the years hundreds of people have been left stranded on the island when the tide comes in.

So the RNLI is trialling a set of traffic lights to warn visitors when they are likely to be cut off.

The lights are being installed on Wednesday - two days after one person had to be rescued from the island after being left stranded by the tide.

Nine others had to be saved over the last bank holiday from the island which is 400m from the mainland shore.

People can get to and from the island during a three-hour window either side of the low tide.

It is a popular attraction for people visiting a Danish Iron Age fort and the remains of a Victorian-era ship which ran aground there.

In a bid to reduce the volume of calls for help, the RNLI has set up the traffic lights to warn visitors about the incoming tide.

The traffic lights will let people know when it is safe to cross, when time is running out and when it is unsafe to walk along the causeway.

The amber light provides a countdown on how much time is left on the island as a return trip takes about 40 minutes on foot.

An RNLI spokeswoman said: "By observing the sign, visitors don't have to second guess how much time they have."

Sully Island can be reached on foot only via a tidal causeway

RNLI community incident reduction manager Nicola Davies said the charity will monitor the effect the lights have on cutting the number of rescue call-outs.

She said "hundreds of visitors have been caught out over the years" by people misjudging the returning tide over the rocky causeway.

"The sign is a pilot and has not been tested anywhere else in the UK," she said.

"Sully Island is the perfect place for it to be tested as we are seeing regular incidents involving people cut-off by the tide resulting in call-outs for Penarth RNLI."

A former haven for smugglers in the Middle Ages, Sully Island is classified as a Site of Special Scientific Interest by Natural Resources Wales.