The 12.03pm Norwich to Cambridge Abellio Greater Anglia service collided with a tractor and trailer on the Hockham Road level crossing near Thetford on April 10, 2016.
A report released by the Rail Accident Investigation Branch (RAIB) said a signaller had given the tractor driver permission to cross the tracks 'when there was insufficient time before the train would arrive at the crossing'.
It said the signaller at the Network Rail signal box at Cambridge had 'lost awareness' of the train's position and it was one minute away from the crossing when the tractor driver was permitted to cross.
The train, which was carrying 135 passengers, was travelling at 87mph as it approached the crossing. The driver saw the tractor moving towards the track and sounded the horn and applied the emergency brake.
But it collided with the tractor and trailer at 84mph, seriously injuring the tractor driver. Four passengers and the train driver also suffered minor injuries.
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The report stated the experienced signaller's competence to operate the equipment safely and effectively was not 'adequately monitored' and his concentration levels 'may have decreased due to a combination of fatigue and a lack of engagement'.
The report also highlighted a decommissioned system of warning lights at the crossing, which the inspector said 'would have probably prevented the accident'.
Instead the crossing, which is situated on a private road, depended on vehicle users opening and closing the gates themselves, after using a telephone to get permission to cross the line from a signaller at Cambridge.
Simon French, chief inspector of rail accidents, said: 'Communicating with level crossing users will be one of many duties carried out by a signaller.
'In an environment where signalling control areas are becoming larger, and the number of crossings overseen by an individual signaller may often increase, it is important that the railway industry considers carefully the measures required to control the risk of signaller error leading to collision.'
The RAIB's report findings:
• The signaller -
The report said Network Rail did not 'adequately define' the amount of experience needed for signallers to maintain their competence to work safely and effectively on the work station in Cambridge.
It also states the signaller did not 'believe the training had provided him with the necessary confidence when using the system operationally.'
He only worked on the system which included the Hockham Road crossing for short periods.
The investigator also stated the managers did not implement a requirement for refresher training on the system and the signaller 'took no steps to increase his own competence'. It added that these 'may have been an underlying factor in the accident'.
• Crossing system -
In 2012 Network Rail had equipped the Hockham Road crossing with a system which provided green and red lights to warn users whether or not it was safe to cross.
The system was decommissioned by Network Rail in October 2015 while a review took place into safety concerns about the system with the system developer.
The RAIB's report states if the system had of been working it 'would have probably prevented the accident'.
The RAIB report made the following recommendations:
1) Reduce the risk of signaller error at user worked crossings.
Network Rail should review its measures for user worked crossings and identify ways of reducing the likelihood of accidents caused by signaller error.
Options for consideration include; improved information for signallers and the closure of user worked crossings.
2) Improve the way new equipment is introduced. Network Rail should review and improve its processes for introducing new signalling equipment. Including training and management of staff who operate the new equipment.
3) Improve the competence of signalling shift managers. Network Rail should review the management arrangements for signalling shift managers, to provide assurance that they are competent to use all the equipment that they may be required to operate.
Network Rail's response to the findings and recommendations
Helen Warnock, Network Rail's senior incident officer for East Anglia, said: 'We take on board the recommendations outlined in the report.
'Since the incident at Hockham level crossing in April 2016, we have already made a number of changes to improve safety. Reducing the risk at level crossings remains a top priority and we are committed to make level crossings as safe as possible for everyone.
'Our thoughts remain with the injured tractor driver and those affected.'
Improvements made by Network Rail at Hockham level crossing since April 2016 include:
• An electronic warning system is now in operation at the crossing, which displays red and green lights that indicate to the user when it is safe to cross thus removing the need to call the signaller.
• The landowner has received additional briefing for his users about how to cross safely with this new technology.
• New ways of working have been introduced at the signal box which will improve how signallers deal with requests at user worked level crossings.
• The installation of additional screens for signallers so they can better track the location of trains on the network.
• A new operations manager with significant operational experience has been appointed to support and lead the local management team.
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