Temporary traffic lights on a busy road running through Sutton and Merton have been anger and confusion by turning permanently red when their batteries expire.

Starting at the Rose Hill roundabout in Sutton, and running along St Helier Avenue in Morden to Morden Hall Road, at least four sets of temporary lights have been installed at pedestrian crossings since April.

But the lights have caused long tailbacks after turning permanently red for prolonged periods of time, leaving road-users having to negotiate their own way across busy crossings. 

Mark Gale, who runs Doggy Boutique opposite one set of lights in St Helier Avenue, said: "Ambulances have been getting stuck going to St Helier Hospital - even they can't go through because it's 100 or so cars in the way.

"The law says you have to obey traffic lights so there are people beeping their horns and people reluctant to go through them knowing the law."

He said the lights outside his shop have failed at lease four times between April 29 and May 18 - and indirectly caused one car crash between confused queing drivers. 

Your Local Guardian:

The work forms part of Transport for London (TfL)'s Road Mordernisation Plan, which involves upgrading the traffic lights from bulbs to LED lights.

Richard Clearey, CEO of the biggest temporary traffic lights supplier in the UK, SLR Traffic Systems, said: "Unfortunately the nature of temporary traffic lights is limited battery."

He said the lights, which his company have supplied in Morden, typically last between seven and 10 days and his company offers a 24-hour maintenance service if contractors request it.

"I don't know what more we can do", he said.

Under UK law temporary traffic lights must turn permanently red when their batteries expire.

Elsewhere in Europe, such as Austria and Switzerland, temporary traffic lights turn flashing orange when their batteries expire, which makes it easier to report the problem, according to Mr Clearey.

Iain Blackmore, Head of Traffic Infrastructure at TfL said on Tuesday: "We apologise for any inconvenience during these works and will discuss with our contractors to ensure that this situation does not arise again."

Contractors Metro Traffic Management, which supplied two sets of temporary traffic lights in St Helier Avenue, denied failing to charge the batteries in time, claiming they had "failed earlier than expected on a few occasions".

Two sets of temporary traffic lights in St Helier Avenue were removed last week. But there are still a number of temporary traffic lights in the area while works continue.

Have you been caught out by the lights getting stuck on red?

Comment below, or email louisa.clarence@london.newsquest.co.uk.