Filton Abbey Wood railway station and the main rail line running through it are to close for two weeks.
The station will be closed for two weeks
The station, near Bristol, will close from 14 to 28 June while workers lay a third track and build a third platform.
The closure is expected to cause delays and alterations to some journeys, and replacement bus services will be in place while work is carried out.
Passengers are advised to check with National Rail Enquiries and to allow extra time for their trips.
Because some trains will be diverted along the Severn Beach line, all trains which normally travel on that route will be cancelled and replaced with a bus service.
The work is aimed at reducing bottlenecks in the area caused by trains travelling between Bristol and South Wales.
A Wessex Trains spokeswoman said: "We apologise to customers for any disruption caused to their journey during this period."