Motorists are being warned to expect delays when work begins on a £1 million subway under the busy A27 north of Brighton.

Drivers have been told to allow more time for journeys while the work is carried out near Falmer.

The subway is being built 50m west of the existing structure to create a new and improved link between the University of Sussex, Falmer railway station and the bus service.

Ing Fischer, Highways Agency project manager, said: "This is an important project for the people in the Falmer and University of Sussex area and will ensure that pedestrians, cyclists and the disabled will have a safe alternative from crossing the busy A27.

"The subway will also improve accessibility to the railway and bus systems.

"Improved features, including state-of-the-art lighting and technology, such as security cameras, have been built into the design, creating an atmosphere of safety.

"Footpaths and cycle tracks connecting to the new larger subway will benefit both pedestrians and cyclists.

"The Highways Agency is committed to keeping disruption to a minimum and we will be keeping two lanes open during most of the work.

"However some delays will occur and people are advised a 40mph speed restriction is being enforced both for their safety and for the safety of our contractors.

"People are advised to allow more time for their journeys."

Two lanes of traffic will be kept open during each phase of work, which starts on Monday.

The roads affected will be the A27 at Falmer and slip roads to the A270 and the B2123.

Weekend work will be kept to a minimum and publicised in advance.

At those times a single contra flow lane will operate in each direction.

Traffic management layout and lane widths will vary throughout the scheme depending on which phase of work is being carried out.

The existing subway suffers from flooding and requires temporary steel props for support. It will be filled in.

Work to improve the cycle track leading to the University of Sussex on the north side of the A27 will also be carried out.