Cracks found on trains led to huge disruption
‘Corrosion, excess movement’ to blame
PASSENGERS IN Yorkshire faced a week of widespread disruption last May after cracks caused by excess movement and aluminium corrosion were found on dozens of trains, an inquiry has found.
Hitachi-built Class 800 trains were taken out of service as a precaution by several operators, including London North Eastern Railway, TransPennine Express and Hull Trains.
Safety regulator the Office of Rail and Road (ORR) said “stress corrosion cracking” was found just above the wheels, because carriages were experiencing more movement than they were designed for.
It is not known for certain why this happened but potential factors identified include wheel wear – which is when the shape of wheels changes during use – and track design.
The ORR also found cracks on lifting points – which allow carThe
riages to be raised during maintenance work – resulted from the use of a particular type of aluminium which was corroded by chloride in the air.
The regulator stated: “Moist air can have significant levels of chloride in it picked up from various factors such as from salt used for clearing ice.”
withdrawal of Class 800 trains until additional safety checks were introduced led to a week of disruption to services.
The ORR said “stringent mitigation measures” such as regular inspections were put in place to allow trains to re-enter service “without passenger safety being compromised”.
The trains have “performed as specified” and “no safety failures” have been recorded.
Recommendations issued by the regulator include the rail industry collaborating to evaluate whether standards for train design and manufacture take into account pressures created by train movement on Britain’s railways.
It urged Hitachi to conduct a formal review of its welding processes, and for train designers to consider what steps should be taken to ensure protection of structures when 7000 series aluminium components are used.
The report also called on the industry to develop a process for responding to similar “crisis events” in the future.