Hairline cracks grounded 182 Hitachi trains — GWR ran three intercity services

In May 2021 cracks were found in more than 180 Hitachi Class 800 trains used by Great Western Railway and London North Eastern Railway, and the affected trains were withdrawn from service. The withdrawal triggered a week of delays and cancellations across GWR, LNER, TransPennine Express and Hull Trains; BBC transport correspondent Paul Clifton reported GWR was at one point reduced to running just three intercity trains, leaving tens of thousands of people unable to travel.

The Office of Rail and Road's April 2022 investigation found the design complied with existing standards, but corrosion cracks had formed on the lifting points — the fittings used to raise carriages during maintenance — because a particular type of aluminium was corroded by salt in the air. Fatigue cracking was caused by the trains experiencing greater loads from movement than the original design allowed, with wheel wear and track design among the possible factors. Cracks were also found when ScotRail's Class 385 and Southeastern's Class 395 fleets were examined.

The regulator recommended a review of industry standards and further work to identify why the cracks developed, while noting there had been no safety failures since the trains returned. Hitachi proposed replacing and modifying affected parts over six years — renting space at Eastleigh Works and taking trains out of service one at a time to keep fleets running — a plan still being finalised with partners when the report was published.

A week of delays and cancellations across four operators; GWR was down to three intercity trains; a six-year repair programme at Eastleigh Works — 'it won't be cheap'.

The alloy met the standards: compliance offered no protection against salt air and loads heavier than the design assumed.

Lifting points concentrate handling stress — the part raised most often turned out to be the part that cracked.

One fleet design serves many operators, so a single defect grounded a whole generation of Britain's intercity trains at once.

A design can meet every standard and still fail: corrosion and real-world loads broke a part nobody tested for both at once.

The ORR said it had been assured of no safety failures and that trains performed as specified after returning to service. Hitachi's six-year modification plan was under review, with the regulator continuing oversight and calling on the industry to 'learn lessons from what has happened'.