First Great Western is encouraging customers travelling on Saturday and Sunday to check journey times and routes as improvement works take place across the Great Western main line.

During the weekend, the railway line between Didcot Parkway and Swindon will be closed while the line between Hereford and Worcester Shrub Hill will be closed on Sunday.

The planned Network Rail works will reduce delays caused by signal failure and prepare the lines for the installation of overhead line equipment, which First Great Western says is a vital step in electrifying the railway.

The following routes will be affected:

London Paddington/Reading to Bath Spa/Bristol Temple Meads and Weston-super-Mare: Train services will operate between London Paddington and Bristol Temple Meads will be extended by about 20 minutes as trains are diverted via an alternative route.

An hourly service will operate on Saturday, August 2, until 3pm on Sunday, August 3, when a half hourly service will return.

London Paddington/Reading to Swindon: A rail replacement bus service will run between Reading and Swindon. On Saturday there will also be a through train service via an alternative route with extended journey times of around 60 minutes.

London Paddington/Reading to Bristol Parkway and South Wales: South Wales routes will alter over the weekend: On Saturday they will call at Chippenham, Swindon and Bristol Parkway and on Sunday they will call at Bath Spa, Bristol Temple Meads and Bristol Parkway. An hourly service will operate. Journey times will be extended by around 75 minutes.

London Paddington/Reading to Cheltenham Spa: Customers on routes between Cheltenham/Gloucester/Swindon and Reading/London Paddington will be able to choose between diverted train services (extended journey times by up to 60 minutes) or fast bus services between Swindon and Reading (extending journey times by up to 35 minutes). An hourly direct bus service will operate on Saturday and a half hourly bus service on Sunday.

London Paddington/Reading to Hereford: Customers travelling from Hereford/Ledbury/Colwall to Reading/London Paddington will be able to travel via Newport London Paddington/Reading to Bedwyn on Saturday. Fast services from London Paddington/Reading to Bedwyn will not call at Theale or Thatcham. Stopping trains from Reading to Newbury will continue to call at Theale and Thatcham.

Swindon to Westbury via Melksham: On Saturday some train services between Swindon/Chippenham and Trowbridge/Westbury via Melksham will be operated by rail replacement buses.

For further service and route information click here

Real-time running information for First Great Western can be found at www.journeycheck.com/firstgreatwestern