London Paddington to Bristol rail electrification creates Swindon jobs
About 100 jobs will be created in Swindon as part of the electrification of the railway line between London Paddington and Bristol.
Network Rail bosses are due to sign the deal with ABB and UK Power Networks Services to provide 30 electricity substations to power the trains.
The first of the stations is due to be delivered in June 2015 with the remainder at six-week intervals
Work to upgrade bridges along the route is already under way.
The route between London and Bristol - including the Newbury to Oxford link - is due to be completed by 2016 with the extension to Cardiff by 2017.
A Network Rail spokesman said electric trains would have 20% more seats than a diesel equivalent, with journey times improved.