Following many of the recent fatal UK rail disasters, members of the public have asked why, if seatbelts have saved so many lives on our roads, are similar restraints not installed on our train?

The final carriage spun off the rails but stayed intact

The Potters Bar crash - where the final carriage of a speeding train was flung across the station's platform - has renewed calls for the seatbelt option to be explored.

Dr Kevin Lotzoff, one of the Barnet General Hospital staff caring for some of the 32 people admitted after the crash, told a visiting Prince Charles that seatbelts might have prevented some injuries.

"Passengers were being thrown through the windows, which broke on impact. They were hitting structures as they were thrown out of the train."

Reduced casualties

Casualties may have been reduced in the crash had passengers been strapped into their seat, says Professor Andrew Evans, director of the University of London Centre for Transport Studies.

Seatbelts already save lives on our roads

"The last carriage retained its structural integrity and remained intact despite the fearsome impact. The deaths and injuries seem to have been caused by passengers being thrown around inside or thrown out," he told BBC News Online.

At Potters Bar seatbelts may not have prevented the horrific injuries sustained, but may have reduced the number of serious casualties, he says.

A hindrance, not a help

However, Mr Evans says that similar accidents where seatbelts would prevent fatalities are rare. "There are crashes where they wouldn't help or might make things worse."

In rail disasters where impacts are so severe that there is no "survival space" left inside a carriage - as has been the case in several UK crashes - no form of restraint would save the lives of the occupants.

Some impacts are too violent for seatbelts

Peter Rayner, an independent rail safety expert, says installing seatbelts on the UK's fleet of trains is not a feasible option and may actually cost lives.

"It's a ridiculous idea. A commuter train into London's Victoria station carries 1,000 people. Insist that everyone aboard is strapped to a seat and 350 will be left on the platform."

Mr Rayner says those prevented from boarding trains because of lack of seats would invariably end up on the roads - where travellers are many times more likely to encounter a fatal accident.

Left at the station

Even if rail bosses and passengers permitted the sort of chaos both Mr Rayner and Mr Evans predict would accompany the introduction of seatbelts, would travellers actually bother to buckle up?

In 1999, the Finnish Railway Authority (VR) installed 271 seatbelts in three of its carriages.

Would those unable to get seats take to their cars?

The year-long project suggested that 26% of people travelling in parts of the train without the belts said they would use them if they had been in place.

However, only 1.1% of passengers in the modified seats bothered to belt themselves in. A third of people who actually noticed the belts were even there, said they looked too uncomfortable to bother with.

The Finns made no further moves to install train seatbelts, a VR spokesman told BBC News Online: "People do not want to use them."