There are delays of up to 30 minutes on the trains between Chippenham and Bristol because of a broken down train.
A group of vandals caused havoc when they attempted to board a train then spray painted the side of the carriage.
A group of up to 20 young people attempted to board the 5.14am Bristol Temple Meads to Severn Beach service on Monday, but were too late.
Several members tried to stop the train doors from closing and were then verbally abusive to staff who attempted to reason with them.
Other individuals then spray painted the side of the carriage - covering the windows and panels in silver and pink paint.
The service was cancelled, and all passengers were asked to alight from the train.
Harry Patch, the last survivor of the First World War trenches, is to have a train named after him.
The Class 43 locomotive will be unveiled at Bristol Temple Meads station this morning by his grandson, Roger Patch.
Harry, who was born in Combe Down near Bath, died in 2009 at the age of 111.
Commuters getting the train from Bristol Temple Meads should expect delays and changes, as a signalling problem is currently disrupting services.
The following changes are expected to continue until the end of service.
- No trains between Bristol Temple Meads and Severn Beach
- Delays of up to 30 minutes to journeys between Bristol Temple Meads and Cardiff Central
A rail union have called the train services running during the current 48-hour strike unsafe.
The RMT union, whose members are striking in a dispute over job losses, safety and buffet cars on new trains, say First Great Western's current emergency "skeleton service", is "dangerously overcrowded" and staffed by people without the right training.
The union say they will be taking this up formally.
First Great Western denied that the trains are overcrowded, and told us staff working on them are fully trained.
The 48-hour strike started on Wednesday night and is set to end at 6.30pm on Friday evening. Staff have been out picketing stations today.
First Great Western say 10% fewer staff have walked out than they were expecting; however the strike has still affected almost 40% of their services.
First Great Western says it should be running more train services during the current rail strike because fewer staff walked out than they expected.
The company says 10% more staff showed up for work than they were expecting.
However it still means that nearly 40% of FGW rail services are affected.
Those travelling can find live service updates here.
The strike, which started last night and is set to end at 6.30pm on Friday evening comes after talks broke down between the RMT union and the company over the new Hitachi Inter-City trains in 2017.
The union have said First Great Western failed to provide "very basic assurances" about safety concerns and job losses. However the company say they have tried to address the concerns and that the new trains cannot be operated "in the same way as the trains we run today, which were built in the 1970s."
They have also played down the possibility of job losses, and say they are "keen to continue discussions with the union".
Plans have been unveiled for improved pedestrian and cycle routes around Temple Meads Station and the new Bristol Arena.
It's hoped the new routes will improve connectivity to the new arena site and have been named 'Temple Greenways'. The routes will link to Totterdown Basin, a little known green oasis where the Floating Harbour meets the Feeder Canal.
Proposals include a new pedestrian and cycle waterside boardwalk, and new paths and seating areas around Totterdown Basin and The New Cut.
Changes are also planned for Cattle Market Road, which will become one-way eastbound for traffic.
Locals, business owners and commuters are now invited to share their views on the proposals. There will be a drop in session on March 26, between 5.30 - 8.30pm.
A rail union will protest across the region today in a campaign against the removal of buffet cars on First Great Western trains.
The RMT says losing the buffet cars will lead to job losses and an 'upstairs downstairs' service on West Country trains. Events will be taking place at Bath Spa and Bristol Temple Meads from 7 o clock this morning.