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TRAIN MANUFACTURER Hitachi is fighting to overcome two types of cracks on its Class 8xx IET fleets, which led to travel chaos in May. The initial problem was discovered during a routine check on April 11 on five-car Class 800/0 800013 at North Pole depot when fatigue cracking was found in some yaw damper bolsters. According to a National Incident Report issued by the RSSB the inspection highlighted a crack on vehicle 814013. It was thought to be just a light surface scratch or score and was removed using emery cloth. Unfortunately, cracks re-appeared in the same area, and following tests it was found they had substantial depth.
The same problem was found on eight sets, predominantly early built examples. The cracks occurred where the yaw damper bracket is welded to the car body, with depths measured as much as 15mm. Although the cause has still to be confirmed, each affected set was a high mileage one, leading to the thinking they are fatigue related. Further testing is ongoing. LNER, Hull Trains and TransPennine Express, all of which use the IET, were advised immediately. The small number of sets involved and the reduced schedules at the time meant passenger services were mostly unaffected.
However, that soon changed on May 8 when engineers discovered more cracks affecting more trains. Industry insiders confirm that the majority of the cracks have been found around the jacking points, behind the lifting (jack) pocket bolster, which are used in depots when trains need to be lifted for maintenance. The longest crack so far discovered is reportedly 285mm and all are in the alloy Aluminium 7000, produced in Japan. While the lifting points are not used as part of normal service, there is considered to be a small risk that parts could become dislodged. Over that weekend Hitachi performed an intense series of tests, which led to a fleet-wide grounding of 182 Hitachi AT300-based trains. Both GWR and LNER fleets were found to have cracks, some severe, in the metal adjacent to the weld point and Hitachi issued an order to stop any unit leaving a depot until it had been thoroughly inspected.
Hitachi issued a statement which said: “Safety is our number one priority and, as a precaution, the decision was taken to halt the entry into service of our inter-city fleets, pending inspection. We understand the frustration caused and we would like to apologise for the inconvenience to passengers and operators. Having been cleared for service, some trains are now running again across the network.” However, the seriousness became apparent later in the day when 80 of the 182 units were taken out of service, with the remainder awaiting inspection. Those withdrawn included 11 LNER sets, 68 at GWR and one with TPE. Hull Trains Class 802s were all cleared to run. By the following morning (May 9) the corresponding number of sets to fail the inspection were LNER 20, GWR 75 and TPE four. In addition, inspections of Hitachibuilt Class 385 EMUs with ScotRail on May 10 found ten with similar cracks near the jacking points.
Significantly, LNER is reported to have found few problems with its electric Class 801 variants, possibly due to their younger age and being lighter due to only one diesel engine. May 9 found the company with 27 Class 801 sets to cover 30 diagrams, but only six bi-mode sets to cover 16 diagrams. The following day GWR had just three of its 93 IETs available for traffic.
Responding to the growing crisis, Rail Minister Chris Heaton-Harris said: “Today [May 9] I have directed the rail industry to urgently set out a comprehensive plan to ensure services can safely resume as soon
as possible. I expect operators to explore all options for replacement services to help people complete their journeys, and have asked Hitachi for a safety inspection plan, as well as a longer-term repair strategy. Our focus is to ensure trains are returned to service as quickly as possible, once they are fully approved as safe. Only then can we start to rebuild a reliable and punctual timetable for passengers. I also want to thank passengers for their patience during what could be a significant period of prolonged disruption, likely to continue for some time.”
Alternative traction
With a date for return to service unsure, operators scrambled to find some alternatives to enable some sort of timetable to be established, notably at GWR. CrossCountry ran extra trains in the West Country and provided GWR with an HST set for use on May 9. Charter train operators also presented proposals. GWR introduced an hourly fast shuttle between Paddington and Didcot, using 12-car Class 387 EMUs, and then extended it as far as Swindon from May 10, and later to Bristol Parkway. CrossCountry also ran a connecting shuttle service between Swindon and Bristol. A process to allow the 387s to run through to Cardiff was also being worked on. Class 165s were initially used on the Bedwyn Shuttles, although these were later supplemented by three c2c Class 378/3s drafted in by First, running as four-cars on the route. Locomotive Services Limited also sent its training rake of Mk 3s from Crewe to Laira in case they were needed and ROG’s 37884 retrieved some former Transport for Wales Mk 3s from store for the same reason.
However, with fewer trains available overcrowding was inevitable, which posed more challenges given the need for social distancing on board. For example, on May 10 CrossCountry’s 0931 Penzance to Newcastle service, formed of a single five-car Class 221 DEMU, had 270 passengers on board when it arrived at Exeter. The 0748 from Glasgow, also a single five-car set, was full and standing when it reached Plymouth at 1744. On May 11 the 1030 Bristol to Swindon CrossCountry HST service was well loaded to a level that would have been uncomfortable with a Voyager.
GWR also considered the options for its ‘Castle’ fleet of short-formation HSTs. It could use the HSTs that were employed by EMR, but if that happened GWR would prefer to use its own power cars on any services that ran into Paddington as they are fitted with ATP equipment. As well as the additional HST vehicles on loan from LSL at Crewe, a rake of Mk 2 coaches from Riviera Trains was also being prepared that could be used with Class 67s. Also being considered were TPE Class 802s, which could be covered in the north by bringing more Class 68/Mk V sets back into service.
LNER fared better as it was able to return a significant number of its fleet to service more quickly. Furthermore, it began reintroducing some of its Class 91/Mk 4 combinations to traffic on May 11, earlier than planned. Great Northern peak services from King’s Cross to Peterborough were strengthened to 12-car sets.
Difficult repairs
The investigation into the cause of the cracking is believed to be focussed on a combination of stress and chemical corrosion. Engineering insiders have refuted suggestions that the cracks around the jacking points might be related to the weight of the underfloor diesel engines, although they do note the diesel-equipped vehicles have a modified yaw damper setup. Substantial samples have been cut from 800026 and more severely damaged 802205 for metallurgical analysis, both in Japan and at The Welding Institute. These include one of the two Class 800 units where cracks were first discovered in early April. The second set is being used as a testbed for repairs.
The Class 8xx series bodyshells were assembled using a friction stir welding technique, and repairing welds in aluminium is a very complicated process. If such welding is required it would mean all electrical equipment in a vehicle being either disconnected or removed to prevent it being damaged by the high temperatures involved. Making this more complicated is the fact that there are only a few facilities able to do the work. The least affected units are being repaired first and returned to service. Those with the original yaw damper attachment issue are being treated quickly, with several already back in traffic after repairs.
The jacking point cracks are a more complicated proposition. But negotiations continue between Hitchai, the Office of Rail and Road, GWR and industry consultant Ricardo to establish an intensive monitoring and risk assessment process. In the longer term it might be necessary to look at an alternative type of repair, even replacing welding with a series of bolts.
Service return
The Rail Delivery Group confirmed on May 13 that “after further rigorous safety checks involving ORR’s HM Railway Inspectorate, GWR and LNER will now begin reintroducing trains with a more regular service for passengers. Trains on some routes may be less frequent than usual, and train availability could vary, for a number of reasons, so passengers should continue to check with the operators before they travel.”
Hitachi Rail Group CEO Andy Barr said: “Today’s agreement [with the DfT and operators] sets out our joint plan for the phased reintroduction of our trains into service, which will continue to deliver the highest possible safety standards. We and our partners have worked around the clock to agree an approach that allows the return of trains to service where they have been deemed safe. With our service recovery plan now underway, we will begin reintroduction of our trains as they are individually approved.”
It is understood that the development of further cracks is unlikely, with a Hitachi spokesman saying, “we’ve been through the whole fleet now with a very thorough exam. The view of the engineers is that the cracks we are finding have been there for a while, because they’re not showing any fresh metal. It appears that these cracks don’t develop overnight, and while there might be one or two that possibly creep over the line, we’re not expecting to find that a load more units have suddenly developed cracks.”
On May 17, the date of the latest timetable change, LNER increased its services. Trains north of Edinburgh to Aberdeen and Inverness resumed over the May 15-16 weekend after the successful completion of further safety checks. Weekday and Saturday services to and from Lincoln have also been reintroduced. An amended timetable is in place until early June while Network Rail continues to deliver East Coast Upgrade works at King’s Cross station. David Horne, LNER Managing Director, said: “I would like to thank our customers for their understanding over the past week and I am pleased we have since been able to step up our services. We continue to work together as an industry on the recovery plan for any affected trains, with all trains being checked before they leave the depot. Safety remains our top priority.”
However, the industry accepts that with each set needing repairs that take it out of service for some weeks, it could take until the end of 2022 before the fleet has fully recovered.