FURIOUS motorists were exasperated this week when adjusted traffic lights designed to improve traffic flow on and off the M5 yet again caused rush-hour chaos.

The "new, improved" traffic lights were switched back on at junction 14 of the M5 at Falfield on Tuesday and drivers faced much the same problems as when the lights were initially installed.

Rush hour queues of up to 20 minutes were reported as the new signals made heavy weather of controlling traffic flows at the busy junction with the B4509 from Tortworth to Falfield.

There was such serious chaos when the system was first activated in mid-February that highway engineers had to switch off the lights after less than half a day. They then remained out of action for six weeks while adjustments were made to the computer controlled sequencing system.

They were finally switched back on on Tuesday but drivers reported only a marginal improvement.

Stephen Coombs from Woodford said: "This was the first weekday morning they have been in action since the first disastrous attempt and once again there were rush hour tailbacks.

"Traffic travelling south from the Stone direction was queued back onto the A38 and traffic coming from the Dursley direction was queued up the hill towards Leyhill.

"If the system causes this much chaos during school holidays, what's it going to be like at peak time on a normal work day?"

Mr Coombs said it raised the question of why the lights were deemed necessary in the first place.

"I've lived in the Thornbury area for 30 years and although the amount of traffic has obviously grown I've never been aware of any regular major traffic problems at this junction other than road accidents and I haven't seen many tailbacks onto the motorway."

Highways Agency officials say the signals and new road markings were intended to smoothe traffic flows and improve safety at the busy junction. They say that in the past drivers have faced problems making right turns from the slip roads and traffic has been known to queue on the motorway at peak times.

Spokesman Nadia Nuami said: "Although there was some queueing on Wednesday morning it was a good deal less than on the previous occasion.

"The system incorporates technology which actually learns traffic flows and adjusts itself accordingly. The situation should improve further as the lights fine tune themselves."