Commuters warned of major rail works in Wiltshire
Commuters are being warned that major engineering work on the Great Western Railway mainline could disrupt travel for the next week.
The work is preparing the 176-year-old line for new faster Hitachi trains that are due to come into service later this year.
Network Rail said the trains are capable of travelling at 140mph, but only after upgrade work is completed.
A £5.7bn contract was awarded in 2011 to the manufacturers of the new trains.
Over the next two weekends, there will only be two high-speed trains an hour from Bristol Temple Meads to Paddington with one calling at Swindon, Didcot and Reading. The other will call at Bath Spa and Reading.
During the week and on Saturday 15 July, there will be a similar level of service but there will only be one train an hour between Bristol Temple Meads and Chippenham.
Train services between Westbury and Swindon via Melksham will also be affected with trains starting and terminating in Chippenham.
Replacement buses services will be offered.
GWR operations director, Rob Mullen, said: "The work is helping GWR take full advantage of our new fleet and will be the greatest step-change in experience for our passengers in a generation."