Keeping the wheels turning on Elizabeth line Class 345s

Philip Haigh visits Alstom’s Old Oak Common depot, to gain an insight into the work that goes to maintaining a modern train fleet.

In this article:

• Old Oak Common evolved from a pioneering 1906 steam depot to a modern Elizabeth line maintenance hub.
• Alstom now operates the facility, focusing on less labor-intensive maintenance of Class 345 electric trains.
• Historic foundations remain, while new tech enables efficient services, including regenerative braking and software upgrades.

When George Jackson Churchward superintended the opening of a vast new locomotive depot at Old Oak Common in 1904-06, the result was widely seen as the most up-to-date facilities in the country.

Boasting four turntables, offices, stores and shops for carpenters, smiths and coppersmiths, it had everything needed to maintain and service Great Western Railway steam locomotives.

Today, the site of Jackson’s pioneering locomotive depot is simply 33 stabling sidings, each capable of holding a nine-car, 205-metre Class 345.

This is the type that runs Elizabeth line services across central London from Reading in the west to Shenfield and Abbey Wood in the east.

Much of Churchward’s depot succumbed to demolition teams in the 1960s, as British Rail converted from steam to diesel traction. All but one turntable went, and that was now open to the elements.

The maintenance facility (known as the ‘Factory’) remained, converted to its new role.

Crossrail demolished what remained in 2011, as it built the Elizabeth line. As part of this demolition, it called in archaeologists to survey the site. They found the remains of the old turntable pits and inspection roads, and even fragments of cups marked ‘GWR - Return to Paddington Station’.

Sitting alongside the stabling sidings is the Elizabeth line’s rolling stock maintenance shed, fully equipped to carry out work up to heavy maintenance and overhauls of the fleet of 70 trains.

In a few years, they will be supplemented by another ten, as the result of a recent order from Transport for London to Alstom in Derby (RAIL 1012).

Alstom operates Old Oak Common’s depot, including the maintenance shed. This shed sits on the site of the old Great Western Railway’s carriage lifting and painting shops, which dated from the 1930s.

More recently, this part of Old Oak Common was known as the Pullman Shed, because British Rail converted the paint shop to maintain, service and repair ‘Blue Pullman’ luxury diesel multiple units that it introduced in the 1960s for limited services from Paddington to Bristol and to Birmingham and Wolverhampton. These services lasted until 1973.

To the south of Alstom’s depot once lay the Coronation Sidings, the original GWR’s massive 15-road carriage shed, and more recently the current GWR’s High Speed Train depot (built in the 1970s by British Rail) and that of Heathrow Express which dated from 1997.

All that has gone, with everything south of Alstom’s site now under High Speed 2’s control. It is the site of its new station, which will sit in a newly dug box that stretches for 850 metres and is 20 metres deep (RAIL 1002).

Where Churchward’s depot might have rung with fitters’ hammers, Alstom’s is quiet. RAIL visited on a weekday morning, which is the quietest time. The peak was over, so the stabling sidings had plenty of trains but the shed itself had few.

Depot Operations Manager James Harrison explained that a typical day’s work comprises a 105-day exam for a Class 345. The train arrives at 0630 and a 12-hour shift of eight people cleans filters, and checks brakes and safety equipment before the unit is prepared for service and leaves at 1830.

With the first ‘345s’ entering service in 2017 (RAIL 830), they now undergo five-year overhauls, while Harrison notes that their 7.5-year overhauls start next February.

The five-year overhauls involved replacing oil in the coupler between traction motors and gearboxes, of which a nine-car ‘345’ has 20.

The 7.5-year overhaul will entail seat squabs replaced in the saloons, with Harrison explaining that this might involve fitting a more distinct design to each train’s 51 priority seats.

Alstom is also working through a programme to fit USB power sockets, which takes four days per train and involves digging into the wiring looms that run through the saloon. This involves removing a lot of the interior.

Staff at the old site would have been very used to changing brake blocks. For older stock, such as Churchward’s steam locomotives, this involved heavy cast-iron blocks. Later stock used brake shoes and, latterly, the fitters in the HST shed would have been changing brake pads.

Alstom has little such activity. Harrison told RAIL that his team was more likely to change brake pads because they had become life-expired, rather than because they were worn. Class 345s have very effective regenerative braking, he explained, so their brake pads see little use. They can last for five years - around 200,000 miles.

Regenerative braking uses traction motors to slow a train by working in electrical reverse, generating electricity and feeding it back into the overhead line system. Not only does this save brake pad wear, it also reduces overall energy consumption.

The depot becomes busier at night, when cleaning becomes the main activity. Every Class 345 is cleaned every night, although only 35 visit Old Oak Common. The rest of the fleet receives cleaning at one of eight outstations, such as Maidenhead.

It takes an hour to clean each train, and this work includes wiping grabrails, mopping floors and vacuuming seats. After cleaning, there’s a 45-minute preparation test, and then each train is ready for service once more.

One road at Old Oak Common (M2) houses the depot’s heavy cleaning facility. This concentrates on roofs, carriage ends and undersides, which the wash plant at the depot entrance does not reach.

Every 42 days, every train goes through the heavy clean, with a team of seven people fully kitted in ‘hazmat’ suits for the work.

On M1 road sits a wheel lathe. During RAIL’s visit, it was being checked, adjusted and serviced by its manufacturer. It usually sees one train per week, working between Thursday and Sunday.

When new, wheels under a Class 345 measure 825mm in diameter. The lathe usually removes 2mm per cut to restore the correct tyre profile, and this typically happens every 140,000 miles. When the wheel reaches 760mm, it will be too small to use and will be replaced.

Harrison hopes to match wheel wear with the time period of bogie overhauls, at ten years. This would make life simpler because his team would only need to swap bogies from under trains. Then wheelsets could be replaced when the bogies go through their own overhaul at somewhere such as Alstom’s Crewe facility, which is currently dealing with bogies from Avanti West Coast’s Class 390 fleet (RAIL 1021).

Old Oak Common is handily equipped with facilities to swap bogies. M9 road is lined with jacks that can lift a complete train from its bogies. Miniature turntables allow bogies to be moved to and from a storage road equipped with an overhead crane.

M7 and M8 roads feature bogie drops just inside the shed entrance. They allow a single bogie to be dropped into a pit equipped with a transfer table that runs under M9 road and onto a lift up to the bogie storage area.

Stillages line the one wall of this area, each with a bogie on board. On the opposite side of the track sit wheelsets. Most bogies are for Class 345s, but Old Oak Common also hosts a couple for Greater Anglia Class 720s with Transport for London’s permission, adds Harrison.

M7-M8 roads feature centre pits and concentrate on heavy maintenance. M3-M6 concentrate on examinations with side and centre pits. In addition, M4 has platforms at train floor level and platforms for roof access, with suitable interlocks to prevent access when there’s power in the overhead line equipment.

Alstom’s Old Oak Common serves the same purpose at Churchward’s, but it has stock that is considerably less labour-intensive. This is a feature of electric stock, but trains today rely more heavily on software than at any time in the past. Getting this right is every bit as important as the work of Old Oak Common’s depot staff.