Rail passengers travelling between Chippenham and Bristol face weeks of disruption during electrification works next summer.

Work to electrify the Great Western main line began at the London end last month, and will reach Wiltshire next July.

Work between Bath and Chippenham that cannot be completed at night is to be combined during a six-week period from mid-July to the end of August 2015.

The first three-week phase will affect only the immediate Box Tunnel area near Corsham.

For passengers travelling west from Chippenham, trains will use diversionary routes, which will extend journey times to Bath Spa.

A Network Rail spokesman said: “Importantly, despite extended journey times, travelling by train between Chippenham and Bath Spa will still be quicker than the same journey by road.”

In the second three-week phase, the entire railway immediately east of Bath Station will close. All trains between Chippenham and Bath Spa will be replaced by coaches.

Passengers travelling from Chippenham to destinations beyond Bath Spa, such as Bristol, will still be able to do so, but journey times will be extended as trains use diversionary rail routes.

Patrick Hallgate, Network Rail route managing director, said: “We realise that this work will cause disruption to rail users, but we are working closely with all the relevant parties to minimise that disruption, and when the work is complete it will pave the way for a massively improved rail service.”

Electrification is expected to cut the journey time from Paddington to Bristol Temple Meads by 22 minutes.

Anyone who wants to share views on the project can go to www.myenvolve.com/project/railelectrification

Network Rail has teamed up with myEnvolve, an independent community engagement app, to run this survey, which was launched in July.