THE safety of driver-only train operations will require "careful assessment" as stations become increasingly crowded, the industry watchdog has warned.

An annual review of safety across the UK's rail industry found significant increases in the number of station and platform accidents, including falls at the platform edge, falls between the train and the platform and a surge in the number of passengers harmed after being trapped in train doors - including six major involving major injury.

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The Office for Road and Rail did not directly link the increase in accidents with the use of driver-only operations (DOO), but stressed that as rolling stock is modernised and the practice becomes more widespread there will have to be "a careful assessment of the different risks".

It comes as hundreds of ScotRail conductors prepare to strike again this weekend in an ongoing dispute between RMT and ScotRail over the potential extension of DOO, where train drivers instead of conductors open and close the doors.

RMT says it endangers passengers because the driver is relying on CCTV to check that the platform and doorways are clear.

The ORR has previously vouched for its safety and stated that its inspectors had "found good practice" among operators.

However, the report added that the increasing numbers of people travelling by train - already up 57 per cent in the past decade - could throw up problems in future.

It stated: "Passenger platform crowding puts pressures on train dispatch, especially at curved platforms, or where station furniture obscures good train dispatch sighting lines.

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"These require regular risk assessment and review of the controls used, staff behaviours, the resourcing applied and proactive monitoring.

"The broader network shift with the introduction of new forms of rolling stock and use of driver-only door operation requires a careful assessment of the different risks caused and controls needed to dispatch trains safely and efficiently."

Brand new trains, designed for driver-only operation, are due to be rolled out on the ScotRail network from December 2017. ScotRail stress that more than half of ScotRail services are already driver-only and that no conductor will lose their job, pay or conditions, but the RMT believes the new fleet will signal a major shift away from the "safety-critical" role of the guard.

The number of injuries sustained in platform edge falls was up 48 per cent year-on-year, including six deaths, although the ORR stressed that none of these occurred when passengers were getting on or off trains. However, the report added that the increase "puts the spotlight on a potentially emerging risk trend".

There was also a 21 per cent increase in harm from falls between the train and platform and a 67 per cent increase in harm from passengers being trapped in train doors, including "six major injury events".

A spokeswoman for the ORR said its position on DOO remained unchanged.

She said: "ORR has scrutinised this approach, and our inspectors are satisfied that with suitable equipment, proper procedures and competent staff in place, it is a safe method of working.

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"Generally speaking, the platform related incidents discussed in the report were not associated with boarding onto or alighting from trains.

"However, there is no room for complacency in areas of safety. The ORR, and the industry, do believe that further improvements in all forms of dispatch are possible."

A spokeswoman for ScotRail said it welcomed the report, adding: "Trains with doors operated by drivers have been in operation in Great Britain for more than 30 years."