The Trades Union Congress (TUC) has urged employers to investigate road traffic accidents in which their employees are involved.
The TUC campaign aims to encourage the Health and Safety Executive to investigate the practices of all employers whose staff drive at work.
The organisation hopes that as a result of the HSE's involvement, managers will take equal responsibility for their workers.
TUC health and safety officer Tom Mellish will tell a Birmingham seminar tomorrow that; "because deaths of employees killed whilst working on the roads are investigated as individual incidents, the root causes behind accidents - driver fatigue, poor state of company vehicles - may never come to light."
TUC general secretary John Monks said: "Workers who drive for a living are more than three times more likely to be killed at work than any other worker.
"Aside from the pain and suffering caused to them and their families, this tragic toll is a massive £3.7bn annual cost to society and a sky high £2.7bn to employers."