IN OCTOBER this year, Switzerland’s BLS rail company head of installations and projects Daniel Pixley took on a new task; upgrading the Lötschberg base tunnel at the centre of his network. For the next four years he manage a CHF 100M (USD 100M) research and design project into expansion of the 34.6km long deep alpine tunnel as well as overseeing network scheduling.
Actual construction and fitting out will take another seven years from 2021 if money is voted through.
Currently the tunnel is largely single track, though it has a 14km length of twin bore in the south. The limitation arises from funding restrictions imposed on the grand Alpine rail transit scheme which the country agreed in 1992 with two main north south axes.
From early on the CHF 4.3bn (USD 4.3bn) western side Lötschberg has been the smaller sister to the Gotthard axis from Zürich to Milan, whose main 57km twin bore base tunnel, the world’s longest and deepest rail tunnel, opens to commercial service at the end of next year.
To save costs on the overall alpine system, money was diverted from Lötschberg. Its full twin tunnelling was reconfigured and a 7km long section of its second bore remains to be excavated while another 14km is excavated but is without fittings or track, though it is used for service and emergency functions.
Now the plan is to fit the empty shell section with track, power, signalling and all the other equipment for full train operations, reducing the 21km of single track operations to just 7km. "There is also a 4km long double track underground approach tunnel at the northern, Frutigen portal" says Pixley "and this currently has only a single track which will be also be replaced with a double configuration."
The overall 18km of additional double tracking will make a huge difference to his main task, managing the operations and maintenance of the tunnel. The long single track section of tunnel currently both complicates and restricts the scheduling of the freight and passenger services through both the up to 2,000m deep tunnel and the original higher mountain line 400m above, with its older 15km tunnel built in 1906. The two lines are used in tandem for greater flexibility. They both fit into an overall 500km long network run by BLS which began as the Berne-Lötschberg- Simplon rail company at the time of the first high tunnel line.
Lötschberg’s single tracking, imposed additional constraints over and above those of a long tunnel from the start. In actually operation it has also seen changes in the tunnel use compared to foreseen use when the alpine base tunnel system was approved.
Originally it was thought the tunnel would have a mixed use with some passenger trains, considerable standard freight as well as roll-on lorry freight, and also car shuttles, much like those used in the Channel Tunnel. The diameter of the tunnel is larger than Gotthard as a result, to accommodate the roll-on loading gauge. In the event says Pixley the train mix developed differently. Passenger use is higher and while freight is also important, some of it continues to use the high line, though larger 4,000t trains can only go on the flatter line. Car shuttles have not been run in the high speed tunnel, which is at full capacity use without them.
Demand for Intercity passenger use from Berne and even Zurich however has been higher than thought initially, the result he thinks of major time savings on the route. This comes not simply from the 20 minutes gained by running at the 200km/hour possible through the base tunnel – faster rolling stock for the 250km/ hour maximum does not yet exist – but also because the base tunnel allows and synchronises with new connections into the network at Visp, which is particularly liked by hikers, skiers and other tourists, going to and from the Matterhorn. On the high line they have to go on to Brig and double back costing another half hour. Passenger use is about 56 per cent he says, against a foreseen 27 per cent. The rest is freight or truck shuttles and a small number of service trains. These are mostly used on Sunday nights when the tunnel is closed for routine works. In the double bore section there is also further maintenance done on Monday’s by shutting one of the two tracks.
Of a theoretical 110 train slots set for the tunnel daily, about 85 are used, this being a 77 per cent utilisation, which is "pretty much close to the limit, extremely high use" he says. The spare time soaks up delays and possible incident. Some days do see 100 per cent and a record 137 has been achieved for a single day’s use. "The ideal concept is that we run an Intercity followed by three freight trains at three minutes intervals going south. Then the line reverses and we have an Intercity followed by one freight train" says Pixley. The additional freight trains return on the mountain line he says. "Usually they are less heavily laden heading north and also there are steeper sections on that side before they reach the tunnel, so some trains already have to double up their traction, which means they are already configured for the steeper mountain line."
But the picture is complicated by the time out for maintenance on Sunday – the six trains per hour exceed the 110 daily total – and by the addition into the schedule of a long distance Eurocity train every two hours. "This reduces the available cargo slots" says Pixley. The base tunnel uses a fixed train path timing system he says, and a train must arrive within six minutes of its allotted time or lose its place. "They would then have to wait or go on the mountain line."
That applies more to freight he says because the necessity of meeting connections on the network makes tight timetabling more crucial for the passenger trains.
The freight/passenger mix, combined with the single tracking also has an impact on speeds says Pixley. Despite a 250km/hour capability for the line inside the tunnel, passenger trains are kept to 200km/hour because otherwise they leave too big a gap before the 100km/hour freight catches up. For logistical reasons a faster service would actually reduce capacity. This will apply to all the base tunnels, including those with twin bore running without reverses in direction.
Trains are controlled into, and through, the tunnel from a central operational control room in Spiez some distance north of the tunnel, via local control centres at each portal, the north in Frutigen and south at Raron. Telemetry and 110 video cameras give the centres full information about the inside of the tunnel and its status, with information on ventilation, the cross passages every 330m, the power supply and other systems. Hot box detectors and other equipment monitor train conditions as the approach the tunnel and inside; "sick" trains cannot enter, or must leave quickly if detected inside.
The controllers can alter the regime for maintenance periods too when the main ventilation fans must be used to drive in fresh air, although normally the tunnels rely on train piston effects to push air through. Power ventilation is also used in case of fire to isolate and exhaust smoke filled areas.
Three teams work round the clock, on traffic control, power systems and the tunnel systems says Pixley, "although the latter functions are being partially merged. The power engineers and the systems engineers are being cross-trained."
The changes are partly due to an upgrade in the tunnel operating system which was done recently. Such is the speed with which digital equipment and computers evolve that the overall operating system needed renewal after a maximum ten years he says. It was done late 2013. "We took the chance to also renew the programmable logic interfaces at the automated control points inside the tunnel, and consolidated the sometimes dozen or so units into a single interface unit. It was more cost effective than waiting for them to reach their full 20 year design life."
Systems are from such firms as ABB which supplied heavy power switching equipment for the train traction and ABAG which did much of the 50Hz power system and cabling for doors, ventilation, cooling, lights and fire detectors. Like most base tunnels, the Lötschberg is deep enough to experience hot rock conditions and equipment has to survive 80 per cent humidity and temperatures up to 35oC. Most of the equipment is located in the cross passages which connect across the 40m distance between the twin bores. These are for safety and for equipment, with pressure resistant safety doors. A container system was used during tunnel fit-out to allow the multiple disparate systems to be assembled and integrated above ground before moving to the final locations.
The cross passages will now serve another important function, by allowing the future upgrade project to be carried out in a phased manner without disrupting train services. Sections between 330m long sections will be done one at a time.
"The problem we face is that the central ’empty’ tunnel bore serves as the emergency rescue route for the main tunnel and cannot be blocked for the long periods needed for fit out. But working one section at a time allows for access arrangement from each end of the 14km section to be used."
The Lötschberg has two emergency train stopping stations along its length from which safety access can be made for this central 14km section, which is to be brought to twin tube status. But just how this operation can be sequenced, and construction and equipment fit out crews can both access the work points, and get in their materials, remains to be worked out. This is a challenge facing the study and design team which will begin work next year.
"We are just tendering to appoint outside consultants for the work now," says Pixley. Some CHF 100M (USD 100M) has been cleared by one of Switzerland’s numerous public referenda for the studies, although he does not think it will need the full allocation. Assuming the full project gets funding, to be decided by another referendum in 2018, it is anticipated these complications will demand a programme of some seven or so years before trains can run. That would be around 2027-8. But the twinning will give a significant improvement in capacity, allowing two passenger trains per hour each way for example, and bringing further capacity improvements for freight which is expected to grow steadily.Of course the full twinning of the line would help even more. That requires a final drive to be made to complete the second bore. Local cantons and business groups are campaigning for this to be done.
"It makes sense to complete the tunnel before it is fifty years old at least" says Pixley. "At that point it will require major renovation – the concrete slab track will be reaching its end-of-life point for example and will need replacing, and other systems too. Such works demand extended closure of the tunnel, perhaps over a year. With a single bore, that would close the axis completely which would throw the entire Swiss and European network off balance he says, whereas keeping one of two bores open would have less impact. Other advantages of a full twin configuration would be in taking all but the lightest freight and passengers from the mountain line. It would therefore need a less heavy duty configuration, saving maintenance and capital renewal costs.
But all that is to be decided as always in Switzerland, by referendums.
