Motorists using the M4 near Chippenham are being warned to expect delays as safety work will take place for three months.

Improvements costing £5 million are to be carried out on the motorway between Junction 16 (West Swindon) and Junction 17 (Chippenham).

The work starts on Monday and continues until May.

During the work only two lanes of the motorway will be open; the hard shoulder and lane one will be closed. These restrictions will be lifted over Easter.

A 50 mph speed limit will be in place during the work and some work will be carried out overnight.

Highways Agency project sponsor Rachel Scott said: “The work has been carefully planned so we can undertake more than one scheme at the same time which will significantly reduce disruption. However, I would advise people to plan their journeys and allow extra time.”

The improvements and maintenance includes the stabilisation of embankments, upgrading traffic signals and the replacement of sections of the steel central reservation barriers with concrete barriers.

The Highways Agency says the new concrete barriers are stronger and more robust. They reduce the risk of vehicles involved in accidents crossing from one side of the motorway to the other and improve the safety of motorists and road workers. The agency also said the barriers are unlikely to require repairs after vehicle impact.

Further work taking place during the same time will be drainage repairs and fence replacement.

Work on the M4 between Junctions 14 (Hungerford) and 13 (Newbury) which has involved installing crossing points is due to be completed by the end of January.

Two crossing points are being installed which will allow traffic to keep flowing following major incidents. During the work there is a 50 mph speed limit and narrow lanes.

Work is also due to begin on Monday on the M5 near Clevedon which will involve a 50 mph speed restriction between Junctions 20 and 21 until April.

This is to enable a new concrete barrier to be installed on the central reservation.