Commuteres and holidaymakers are being warned to expect major disruptions to rail services through Trowbridge and Westbury this summer.

Passengers are being urged to allow extra time for journeys, particularly if they are travelling to airports, as some services will be replaced by buses.

The delays in July and August will be caused by the electrification of the Great Western mainline between London Paddington and Bristol Temple Meads as work starts on the Chippenham to Bath section.

The first stage of the work is planned for July 18 to 31 disrupting the Chippenham-Bath section to allow electric cables to be strung through Box tunnel.

Passengers travelling to London from west Wiltshire via Bath will instead have to pick up the service at Bristol, or use an hourly service from Bath to Chippenham on an alternative route to London.

During stage one, Westbury to Bath should be a near normal timetable, while Westbury to London Paddington should not be greatly affected.

The Heart of Wessex line connecting Bristol via Trowbridge and Westbury to Weymouth will be disrupted. Cllr Horace Prickett, passenger transport portfolio holder for Wiltshire Council, said: “The current electrification... is the largest project since the war. Full details are still being worked out.”

During stage two, from August 1 to 31, the Avon Valley line connecting Westbury to Bath will close completely and replacement buses will operate to stations from Westbury to Bath.

From Trowbridge, West- bury to Cardiff trains will divert via Swindon, with alternate trains calling at Melksham. The Bristol to Waterloo service will not run from Trowbridge in August, but may start from Westbury.