ORR releases its review into Hitachi Class 80X cracking
THE OFFICE of Rail and Road has released its comprehensive report into the cracks that were discovered on a large number of Hitachi-built trains operated by London North Eastern Railway and Great Western Railway.
The problem was first discovered during routine maintenance in April 2021, with cracking discovered around the yaw damper brackets and anti-roll bar fixings, where the vehicle load is transferred to the train bogies. Examination of the GWR train fleet, where the problem had first been identified, resulted in eight trains being found to be significantly affected by the issue and withdrawn from service.
On May 7, 2021, further cracking was discovered around the weld lines where the train lifting plates are attached to the vehicle bodies, with a potential risk of the lifting plates becoming detached.
The following day the decision was taken to withdraw all 182 Hitachi Class 800, 801 and 802 trains that were operated variously by LNER, GWR, Transpennine Express and Hull Trains, until the trains had all been examined and the scale of the problem identified. This led to widespread service disruptions.
Cracks were also found on Hitachibuilt Class 385 EMUS operated by Scotrail and Class 395 ‘Javelin’ trains operated by Southeastern, but the decision was taken that these two fleets did not need to be withdrawn from service as the issue was considered to be a low risk.
Report findings
It has been found that the corrosion cracking problem in the jacking plates stems from the use of 7000 series aluminium, which is susceptible to stress corrosion cracking, particularly in plates thicker than 10mm. The cracking around the yaw damper brackets is due to fatigue suffered by the trains experiencing greater loads than they were designed for, with wheel wear on the trains and track conditions also identified as possible causes.
Hitachi Rail’s proposed permanent solution to address the fatigue cracking issues in the bolster area is to remove the affected part of the original body structure, including the longitudinal welds where the fatigue cracks have occurred and the mounting brackets. The structure will then be rebuilt using a modified design that provides an unchanged interface with the yaw damper bracket and anti-roll bar.
With so many Hitachi trains now built and in service, it is expected that repairs will take place over a period of six years, with trains being treated in order of priority from inspections and monitoring carried out so far and through ongoing maintenance. Repairs will be carried out at Arlington Fleet Services at Eastleigh.
Monitoring
Trains that have not experienced the cracking issues to date, such as the Lumo Class 803 EMUS, and designs that are under construction at the moment, such as the new trains being built Avanti West Coast, will be modified at the end of the programme to match the other fleets. The trains will be routinely monitored in the meantime.
The Class 810 bi-mode trains being built for East Midlands Railway will also be monitored, although they are built to a different design than those that have been affected.
The Office of Rail and Road’s HM chief inspector of railways, Ian Prosser CBE, said: “With our oversight, Hitachi Rail and operators have put in place robust plans to make sure the right safety issues are being managed following the initial discovery of cracks on the trains, which have allowed trains to re-enter service.
“Safety remains the number one priority. Our review provides a clearer picture of the issue and we will continue our oversight to ensure work moves forward to agree the permanent solution and that our recommendations are acted on.
“It is important that the whole industry works together to learn lessons from what has happened and our recommendations will help with that.”