Motorists faced a nightmare journey along the M5 to Bristol as roadworks began on the motorway – and the cones will be out until Christmas.

Major resurfacing and waterproofing work started on the northbound carriageway at Avonmouth Bridge yesterday.

There was a 50mph limit in both directions, enforced by cameras, along a 3,000-metre stretch between junctions 18 and 19 for the installation of a contraflow system.

The Highways Agency anticipated delays of about 10 minutes but commuters said it was taking up to one and a half hours to get from Weston-super-Mare to Bristol, a journey which normally takes 30 minutes.

Avonmouth Bridge was opened in 1974 and carries 60,000 vehicles a day in each direction. Before last year's work on the southbound carriageway it had not been resurfaced since 1995. Since then, high levels of traffic and harsh weather have caused the bond between the concrete deck and surface to fail.

A contraflow system will also be set up between the northern end of Avonmouth Bridge and Junction 17, the turn-off for Cribbs Causeway today so that the barriers can be replaced.

During the work there will be narrow lanes and a 50mph speed limit controlled by speed cameras. At times there will be a contraflow.

Three lanes will remain open in each direction throughout the work, which will continue until December 6.

Emergency recovery will be provided within the working area to deal with vehicle breakdowns and help keep traffic moving.

If it rains a lot in the next couple of months the work will take longer.

Highways Agency project manager David Stock said: "The existing surface to Avonmouth Bridge was laid during the previous strengthening contract which started in 1995 and has reached the end of its effective life.

"We will be using a new resurfacing material which, unlike some of the existing material, is able to be machine laid, providing an improved surface finish. The new material is designed to last longer and give a smoother ride than the existing surface.

"A new concrete barrier will be installed between the bridge and Junction 17. The new barrier will replace the previous steel barrier and is designed to improve safety by reducing the risk of crossovers.

"Work will take place at every available opportunity to minimise the duration of these projects, including day and night. However, due to practical considerations such as unsuitable weather conditions, excessive noise or safety, some periods of inactivity can be expected.

"Some peak time delays should be expected during these essential works and drivers are advised to allow more time for their journeys. We regret any inconvenience this will cause."

Replacing the Lawrence Weston bridge on the M5 between junctions 17 and 18 will begin in December.

The bridge has been closed to traffic for a number of years and will be replaced with a single span structure for pedestrians and cyclists.

It will be necessary to shut the M5 for 16 hours to demolish the bridge, which is planned for Christmas Day to minimise disruption.

Philip Gomm, of the Royal Automobile Club Association, said: "Any disruption can have a big knock-on effect. For drivers worried about what their journey might hold in store they can check the Highways Agency website or ring the call centre on 08457 504030 to get real-time information."