Babcock Rail has been fined £400,000 for its role in a 2013 incident which left a worker with leg, abdomen and back injuries.
The company was fined for breaching health and safety laws, following a prosecution by the Office of Rail and Road.
A worker was injured while renewing rail track in Flintshire, north-east Wales, two years ago.
On 8 March 2013, a Babcock Rail employee was struck by a road-rail vehicle and trapped against the platform edge of Hope railway station, leaving him with injuries to both legs, abdomen and back.
The ORR said Babcock Rail was aware there was a risk of collision between maintenance vehicles and workers renewing the track at Hope station.
It said the company ”failed to take appropriate steps to prevent its employees coming to harm following inadequate planning, co-ordination and communication between managers”.
The prosecution found that a 3 mph speed limit for vehicles was ”not being monitored or enforced, and no attempts were made to set up exclusion zones or positions of safety for those working near moving vehicles”.
HM chief inspector of railways Ian Prosser said: “This was an avoidable incident which left a rail worker with serious injuries. Babcock Rail’s safety management fell below the standards required, as inadequate planning and co-ordination of track renewals placed workers in unnecessary danger.
“Safety of rail workers is one of the regulator’s key priorities and we will take appropriate action against companies or individuals wherever failings are found.”
Several contractors have received heavy fines in 2016 to date following road and rail incidents.
A Babcock Rail spokeswoman said: “Babcock is committed to maintaining and delivering the highest standards in the management of health and safety in all we do. The health and safety of all employees has always been a top priority and we are also committed to ensuring our staff are trained to the highest standards.
“Following the incident three years ago, we established a thorough and immediate investigation. We have a strong track record for health and safety and this remains an isolated case.”
Carillion was fined £200,000 last month after an investigation into the death of a railway worker in 2012.
Balfour Beatty Civil Engineering was last month fined £1m after the death of a road worker in 2012.