The company's fleet of 700 vehicles, including 350 light commercial vehicles and 250 cars, won the award at the Fleet Safety Forum Awards, organised by road safety organisation Brake.
EW&SR has introduced two specific maintenance policies, one for sub-3.5 tonne vehicles and another for heavy vehicles.
These include defect reporting and require drivers to inspect vehicles before they begin a journey using a form that specifies items to check and action to take if they identify a defect.
The rail firm has also commissioned independent engineers from Leslie Reeson to carry out quality maintenance audits, and verify that maintenance has been carried out to the required standard. And it has invested in fleet management software to provide a trend analysis and maintenance diary.
Barry Illing, road fleet manager of EW&SR, said: 'Our drivers are responsible for signalling defects and sending the information to our fleet management company.'
He added that the pro-active approach to maintenance was saving the company money because defective parts were replaced before they developed into a full scale fault, improving vehicle reliability.