Destination Gotthard

Their working day begins at 07:30h in the morning at the SBB works in Biel. This is the SBB center of excellence for maintenance and repairs to its diesel-powered rolling stock, and the starting point for the trial runs taking place all week to commission the new maintenance vehicles. SBB trials manager Sepp Zimmermann welcomes the team of twelve. He briefs them with the news that some things did not go well the previous day, resulting in some engineers having to burn the midnight oil, making modifications to the vehicle control system. Today's runs between Langendorf and Gänsbrunnen will show whether these have helped. Two special points of note will be a slight uphill run of 1 in 35 (2.8%) and the section through the Weissenstein Tunnel. A mere 3.7 km long, and taking less than five minutes end-to-end, this narrow tunnel built in 1906 is not really a dress rehearsal for the Gotthard Tunnel, but the necessary permission has not yet been granted to travel through the Gotthard.

Everyone is happy when Zimmermann dismisses the group, because it's freezing cold. Hagen Kestin, though, is standing there, the only one in a T-shirt, exuding the calmness of someone who really knows his trade. The man who trained as a communications electronics technician has been commissioning rail projects for mtu for ten years. This has taken him to many parts of the world – from the Siberian cold to the desert heat. And, despite the routine, anyone meeting him notices right away that his love for his work has not been left on a train somewhere along the line. For Kestin, too, this new vehicle for the Gotthard Tunnel is very special.

A very special vehicle

Standing in the driver's cab of the bright yellow railcar now is Peter Gerber, the SBB Technical Project Manager responsible for its procurement. His eyes gleam, and his voice resounds with enthusiasm when his turn comes to answer questions on the vehicle known, somewhat blandly perhaps, as the 'Xem 181 011': “No doubt about it, this vehicle is certainly very close to my heart,” he says, “I've been working on the project right from the ITT stage.” Harsco Rail had responded to the invitation to tender with a winning design which has now been turned into reality. The design concept tailor-made by Harsco engineers to SBB requirements is packed full of impressive technical features – including automatic clutches at both ends and compatibility with the European Train Control System (ETCS) standards.

“But the most special feature is the hybrid traction system,” says Gerber. “We can drive under electrical power or diesel power. The train driver can switch from one to the other with ease, even without stopping.” Gerber points to two buttons on the control console: one is marked E (for electric), and beside it is a button marked D (for diesel) which is illuminated, indicating that the train is being powered by the mtu PowerPack – as it will be for most of the day. In everyday use, this will rarely be the case: “We're assuming that we will use diesel mode for around 400 hours per year,” explains Gerber. Most of the time, the vehicles will be traveling under overhead power lines. Only if these fail or have to be powered down for maintenance purposes will the mtu PowerPack swing into action right away from its ever-ready standby mode.

On safety duty

The 57 km long Gotthard Tunnel is not just set to be the world's longest railway tunnel, but the safest too. And a lot of effort is going into this. In addition to fire-fighting and ambulance rolling stock, which are also fitted with mtu traction systems, SBB is procuring a total of 13 maintenance railcars and 18 engineless tenders with a variety of technical design-finishes for use in this record-breaking tunnel. The first of these vehicles is due to go into service at the beginning of 2017. Their main task will be to inspect and maintain the tracks, catenaries and other rail infrastructure deployed in the tunnels: “Lighting, ventilation systems, safety installations and radio systems all have to be checked continually,” explains Peter Gerber. This even includes regular rinsing out of the huge drainage shafts: “to prevent stalactites from forming.”

Nocturnal logistical feats

Each weekend sees one of the two tunnel tubes close at night. Once that happens, there's no hanging around: “A total of three trains are brought at high speed – up to 100 kph – from the SBB Maintenance & Intervention Centers in Erstfeld in the north and Biasca in the south. Each train is made up of three to four maintenance railcars with tenders in between, and takes up its position at a different location in the tunnel.” Gerber refers to this as 'time-optimized dispatch' within the tunnel: In order to make the best use of time available within the tunnel, the teams of up to eight people per maintenance car work simultaneously at different locations. At the end of the shift, the individual cars reunite into trains, and another technical gem of the 'Xem 181' comes into play: “A lead car is able to take control of others attached to it,” explains Gerber.

mtu – the driving force

In order to ensure that speeds of 100 kph – which are unusual for service railcars, but imperative given the distances involved – can also be attained when overhead power lines fail or are taken offline for maintenance purposes, each railcar is fitted with an mtu PowerPack housing a 12-cylinder 12V Series 1600 R80L diesel engine. Developing up to 700 kW of traction power, this is the most powerful engine in its series. With its built-in SCR exhaust aftertreatment system, the PowerPack meets the stringent EU Stage IIIB emissions standard. As well as the engine and alternator, the PowerPack contains all the systems needed to deliver traction power. Even the working power needed for on-board equipment – including a large crane on the rear work platform – during diesel-mode operation is produced by the mtu PowerPack.

Taking the engine's pulse

Sitting immediately above the engine, separated only by the railcar floor, is Hagen Kestin with his notebook PC, radioing his next requirements to the driver: “Move off at 50%. And have Bobo give us some push.” Bobo is the Type Re 420 brake locomotive coupled to the railcar: without its braking power the maintenance railcar would exceed the 60 kph speed limit prescribed for test runs. Kestin taps into the engine control unit via his notebook, whose display lights up with brightly-colored graph curves. “The amplitude tells me how the engine is doing,” says Kestin. He is, so to speak, taking the drive system's pulse. He monitors various temperatures – of the engine, the coolant and the exhaust – and the pressures (charge air, oil and fuel system) and, finally, the oil and AdBlue levels and the status of the ventilation control system. All these curves have to be brought into a kind of harmony with each other which laypeople do not really follow – but Kestin has very clear ideas of what the image has to look like: “That point is not so great,” he suddenly says, his voice tinged with dismay.

The paramount objective of Kestin's work is to adjust the engine's electronic control system in such a way that the engine always runs in its sweet spot. This means the engine is using as little fuel as possible, giving off as few emissions as possible and building up maintenance requirements which are, similarly, as low as possible. Before leaving the factory, the mtu PowerPack has already been put through its paces at great length on the company's own test stand. “That's where 90% of all issues come to light,” explains Kestin. But, once installed, what the engine wants to do has to be brought into harmony with the demands and characteristics of the vehicle in question. How traction system and vehicle get on together in real life is something that only comes to light once they have been married together and the driver has pressed the red start button for the first time.

Heavy-duty test heaven

Time and again, Kestin has the driver move off under a variety of loads. And then stop. Move off. Stop. Then the engine is switched off: The engineers from Harsco Rail load new software into the electronic control system. They had fine-tuned this in line with readings taken during the trial run. It is at such moments that you understand why good teamwork is an important part of any successful commissioning.

“Now let's get the PowerPack right up to full working temperature,” radios Kestin to the driver. The driver is only too happy to oblige and shifts the drive lever to 100% traction power. Kestin has his eyes on the laptop, seeing the charge-air temperature rise slowly. And then something happens that propels him straight to seventh heaven: when a temperature limit is reached, the engine management system responds suddenly by reducing engine power. Simultaneously, the train control system demands more electrical current from the alternator. You can see now on Kestin's screen how the charge air temperature drops back, a tenth of a degree at a time. And, as suddenly as the temperature curve dropped below its limit, engine power is boosted again, accelerating the railcar because the train asked for more current. “Beautiful!” shouts Kestin. As recently as yesterday, this test had caused the engine to shut down – resulting in much burning of midnight oil – but today vehicle and PowerPack are communicating perfectly.

Commissioning brings people together

Harsco engineer Lorenz Trachsel, too, breaks into a smile in his seat behind Kestin. The next thing one might expect to see would be the two colleagues high-fiving each other – but that would perhaps be a little too euphoric for our two commissioning gurus. Lorenz Trachsel has been working with a group of specialist engineers for two and a half years now, working on fine-tuning the vehicle and has met with his mtu colleagues several times during this period for meetings in Aachen, Friedrichshafen and Switzerland. They have long developed a close working relationship in this time, and you notice how they are all really pulling together. “It's great fun taking care of a project like this and making progress,” says Trachsel.