Darlington in the North East of England has an illustrious place in railway history. It was one of the termini of the Stockton and Darlington Railway, which in 1825 became the first commercial, public railway line to use steam locomotives.
In July this year, Darlington notched up another first, becoming the base of operations for a new train to operate on Britain’s railways. But on this occasion, neither fare-paying passengers nor freight are involved. Instead, the locomotive is the mobile maintenance train (MMT), a three-carriage unit that is expected to revolutionise the way track repairs are carried out.
The train is a self-contained repair facility that fulfils two functions. First, it carries a maintenance crew and all their equipment to the point where work needs to be carried out, and then stops right over the stretch of track involved. Second, it then provides both the power to drive the equipment the team will use and an enclosed environment in which they can work, protecting them from the elements and any passing train on an adjacent track.
The three carriages that make up the train comprise:
- a traction and supply unit that provides motive power for the whole train; a 140kW generator supplying electrical, pneumatic and hydraulic power; and both crew accommodation and a workshop area;
- an intermediate car (IC) that provides a storage area including an underfloor capacity for six 13.7m long sections of track and an associated loading capability via hydraulic lift gates on each side;
- a mobile maintenance unit (MMU) – effectively a carriage with no floor, which allows the crew direct access to the track while providing shelter from above and the sides.
The train will make it much easier to get out on-site to repair stretches of railway track. Corey White, the supervisor of the train and effectively the onboard manager for the maintenance crew – normally five-strong – who will work on the track, says the concept is new to the UK’s rail network and should make a big difference to the speed and efficiency with which repairs can be carried out.
A key factor is the ease with which a repair crew can be delivered to the work site, says White. Without the train, the team had to be transported by road to the nearest access point to the tracks, and then walk to the required position, carrying equipment, sometimes in adverse weather. The train should obviate conditions that waste time and tire staff even before they start work. But the train also makes the repair work much easier.
It does this first through the protected environment it provides for the repair team. They can step down onto the track from the MMU without even having to go outside the train. They are then inside an enclosed area defined by the two ends of the MMU and its sidewalls, which can be extended outwards by hydraulic actuators to create a working space 16m in length and up to 3.2m in width. The minimum separation of 2m is used only when the train is in motion. Apart from protecting the team from the elements, this feature also means that staff can work in complete safety even if the adjacent track is in use by passing trains, although negotiations with the unions are continuing to gain approval for this to happen.
The second way the train facilitates the work is that it is an active resource for effecting repairs. The MMU is equipped with two 2.5-tonne capacity hoists that extend back into the IC to enable the manipulation of heavy loads – new lengths of track can be lowered straight into place. And onboard power generation makes available tools – both electrical and pneumatic – to support the crew in tasks down on the line. The voltage is 415V AC.
One interesting aspect is that work can take place on the move. The train can creep forward at just 0.2mph (0.32km/h), allowing the crew to work continuously on longer sections of track than can be covered by the MMU, without needing to reboard the train to enable it to be repositioned. To make this process safe, two laser beams are installed across each end of the working area – any transgression will automatically halt the train. So there is no chance of the team coming into contact with moving wheels or heavy train structure.
Another layer of safety built in is a console operated by White from a vantage point above the work, which gives him an effective veto over the train’s movement. Without activating a switch at the console, it is impossible for the driver to put the train into normal motion. A system of video cameras also provides views of the working area and train exterior for both supervisor and driver, to ensure that each has full knowledge of what is happening, and where, on and around the train.
White is confident the train will enhance the efficiency of repair and maintenance operations. He cites the task of replacing a concrete sleeper. Previously, this might have required an eight-strong team, who would first have had to push the sleeper to recover before starting work, he says. The whole job could easily take them a day. In contrast, the MMT team has already carried out such a task in an hour and a half.
The MMTs are built in Germany by train maker Robel and cost £5.5 million each. Eventually, there will be eight of them. Two more are due to go into operation this year, one based at Paddock Wood in Kent and the other in Derby. The other five will follow on next year, with the final train due for delivery in August, and they will operate from Woking, Retford, Peterborough, Horsham and Romford.Their introduction will be overseen by programme manager Craig Mathys. The MMT concept is not new, says Mathys. Such trains are used elsewhere in Europe – the UK trains are closely modelled on units in Norway – and there is also one in the US. However, the UK trains are a specific design variant to cope with particular requirements, involving such factors as the railway gauge and maximum permitted bogie separation, he says.
The idea had been mooted within Network Rail for over a decade, but the go-ahead to implement the approach was finally given a little over two years ago, says Mathys.
Plenty of areas have been identified where the trains could bring improvements. These include, he says, “workforce health and safety, network availability and simplified efficiency targets”. He has no doubts that the investment involved will prove worthwhile. “These trains will contribute to achieving those targets,” he says.
While the tasks carried out from the trains will all be routine, they may also enable welding to be done in weather conditions in which it would otherwise not be feasible, he adds. To support such operations, the trains are equipped with a fume extraction system.
The UK may have followed other countries in adopting the MMT approach but the number of trains involved here will be unprecedented, says Mathys. “No other country has as many as eight.” Others have just one or two.