INTRO: Construction of a 21 km automated metro in the Danish capital is well under way, with two TBMs being positioned for their second drives under the heart of the city. Andrew Hellawell visited the sites to see construction work in progress

BEHIND THE quayside at Havnegade in central København a 20m wide shaft sinks down to 25m below sea level. The nearness of the harbour to this underground construction site is an obvious problem. And yet in this most environmentally-conscious city it is a bonus. With all remaining tunnelling being done from Havnegade, almost all the spoil and tunnel lining segments can be moved by barge.

This explains the perhaps surprising order in which the city’s Y-shaped Metro network is being built. Early last year the two Tunnel Boring Machines (named Liva and Betty after two famous Danish actresses) set off from a large construction site at Islands Brygge on Amager. They have now driven a pair of 5·5m diameter tunnels 600m long to the grade-separated junction at Christianshavn, which has been dug using NATM in the limestone strata.

Comet, the civil engineering consortium building the Metro celebrated the first tunnel breakthrough on September 1 1998. With the first drives completed, Islands Brygge ceases to be a tunnelling base. Work on constructing the cut-and-cover ramp up out of the tunnel and onto the elevated line south to the Ørestad development zone is under way, and soon the district will once again be a quiet residential area.

Having completed these short tunnels, the TBMs are being dismantled and reassembled at Havnegade. From here they will first drive southeast under the harbour, passing through Christianshavn and continuing down the eastern branch to Lergravsparken. They will then be dismantled and taken back to Havnegade a second time, ready to tunnel westwards to Nørreport and Frederiksberg.

The great majority of tunnelling is in limestone, and the spoil makes ideal fill material for the new island of Peberholm, now rising out of the sea off the east coast as part of the Øresund fixed link project. Removing spoil and bringing in tunnel lining segments directly by sea will avoid thousands of heavy lorry journeys through the historic centre of the city.

More access, less intrusion

Of course, a project on this scale is bound to cause disruption. Hoardings around the site of Kongens Nytorv station near the picturesque Nyhavn in the old city are a visual intrusion. But when completed, the station will have little visible presence, despite being the centre-piece of the Metro, as almost everything is below pavement level.

The station fills a 20m wide trench excavated to a depth of 20m, for a length of 60m. A double piling technique was used to create the box walls, so as to minimise any lowering of the groundwater level which might lead to damage to nearby building foundations.

Platforms are at the lowest level; with twin sets of escalators for both up and down linking to the ticket hall via a mezzanine level through otherwise open space. Stairs connect up to the street, and there is access by glass lift direct from street level to the platforms for disabled passengers. Pyramidal skylights emerge through the pavement, guiding daylight directly down to the platforms; at night, station lighting will shine up through the skylights.

The station concept was designed by architects KHR, which also created the look of København airport’s main line station that opened last September. KHR has endeavoured to use a similar styling, which will give the city’s transport infrastructure a family resemblance.

Running tunnel access shafts are being constructed between stations so that the maximum distance between exits is 600m. In an emergency, passengers will disembark onto a continuous side walkway at car floor height, and proceed to the nearest exit which will never be more than 300m away. Between stations, the running tunnels dip so that the gradients assist trains to brake and accelerate, reducing both brake wear and power consumption.

One of the most important stations will be the interchange with DSB’s S-Bane and Regional trains at Nørreport; this is expected to be the busiest stop. The existing station has quite a cramped layout, so detailed analysis of passenger flows was necessary to ensure it will be able to handle the traffic. The metro station will have its own entrance and ticket hall, leading to a pair of twin escalator routes down to the platforms. Separate escalators from the metro platforms will provide a direct connection for interchange passengers to an existing subway linking the two main line island platforms.

The most visible signs of progress are on the line south from Islands Brygge. This section of route is almost all elevated, running across the open space of Amager Common. A strip of this adjoining the west side of the existing suburban development is to become the new Ørestad district. Amager Common remained undeveloped as it had been used as a military firing range until 50 years ago - something which has posed some problems for construction, as remaining hazards had to be cleared by bomb disposal teams before work could begin.

With the land cleared, construction could proceed quickly across the greenfield site; 2·5 km of the 3·0 km viaduct and half the 2 km of embankment are now complete. Ballasting, tracklaying and other fitting out work has already begun around Vestamager.

Control centre and depot

Beyond this station the line drops down from the viaduct through a 180° turn to access the Control & Maintenance Centre on the east side of the line. This also houses the Metro’s administrative facilities and a test track. A Scada system will be used to monitor all equipment, including pumps, ventilation and escalators, and this can exchange data with the Automatic Train Control equipment, allowing integrated operation of the entire metro. The control centre will normally require a staff of only four or five to operate the network.

Towards the southern end of the line is the Ørestad interchange station linking the metro to the Øresund link approaches. This will provide connections with DSB services to and from København airport and also with services across the Øresund following the opening of the link due next year.

Environmental intrusion is a major concern for the city, and particular attention is being paid to minimising vibration from trains in the tunnel sections. With the line running close to national monuments and sensitive buildings such as the National Bank and Broadcasting House, slab track will be used, and vibration tests will be carried out to ensure that sufficient vibration absorption is built into the track bed.

Rolling stock

The railway systems contractor is Ansaldo Trasporti, which has developed the rolling stock design in conjunction with styling consultants Giugiaro. The complete network will require a fleet of 34 three-car EMUs; the first is due to be delivered by June 5 1999. A three-car set will weigh 52 tonnes, and will be able to accelerate at up to 1·3m/s2 to 80 km/h. Power is drawn from a bottom-contact third rail at 750V DC. As well as reducing the diameter of tunnel needed, third rail was also favoured to minimise the visual intrusion of the metro on the elevated sections on Amager.

With the great majority of journeys taking less than 3min, the emphasis has been on capacity and functionality rather than seating, though there will be seats for 96 of the 300 passengers able to board a three-car train. As well as plenty of standing room, there will be space for wheelchairs and prams, and to accommodate the local population’s enthusiasm for prams and bicycles on public transport.

Level boarding will speed loading and unloading at stations to reduce dwell time, and underground stations will have platform screen doors. A wide central aisle and full-width inter-car gangways will aid dispersal of passengers within each train. Electronic signs will provide on-train information about the next station, and details of transfers to other trains and buses. Although no driver is required, roving staff will help passengers and inspect tickets both on and off the trains.

Passenger focused

Foremost during the design stage have been the needs of passengers, but this has also influenced the way the Metro will operate. It will be the first metro in Europe to offer a guarantee that delays will not exceed 30min, even to passengers changing to other modes of public transport. In the event of a longer delay, they will be able to reclaim up to DKr200 for taxi fares.

A strict incentive scheme will be in place between Ørestadsselskabet and the operating company to be set up by Ansaldo, with 98% service reliability marking the division between penalty and bonus payment. Fully-automated operation offers the opportunity to run trains right through the night at low cost, and a 15min frequency is projected. This will reduce in phases to the minimum 90s headway on the central section during peak periods. Trains should average about 40 km/h. As well as supplying the trains and related systems Ansaldo Trasporti will also be responsible for operating and maintaining them for five years.

Safety is monitored by the Danish Railways Inpectorate, which issues approvals upon submission of the necessary safety case documentation from Ansaldo, the operator and an independent consultant. With no previous metro experience to draw upon, it was decided to adopt the BOStrab standards used in Germany. TÜV Rheinland won the contract to provide independent safety assessment with Det Norske Veritas as subcontractor.

Next phase

While attention is focused on getting the city centre section open by 2001, and the western extension to Vanløse by 2002, another priority is securing the funding needed for completion of the eastern branch on Amager from Lergravsparken through Kastrup to the airport. Unlike most of the rest of the network, all but 200m of this 4·2 km section is at grade, occupying the right-of-way of an abandoned freight line. Consultants Carl Bro and Maunsell began design work on this, and the Vanløse extension, in mid-1998.

Even before the Metro is completed, København Municipality should have made a decision about boosting public transport capacity under its Projekt Basisnet study. One option envisages further metro construction, with light rail and upgraded bus feeders.

CAPTION: The main tunnel drives will start from the Havnegade shaft in central København, allowing the easy transfer of materials and spoil to and from barges

CAPTION: The 34 three-car trainsets being supplied by Ansaldo Trasporti will have wide inter-car gangways. Each will carry up to 96 seated and 204 standing passengers

CAPTION: Construction of the Metro Control & Maintenance Centre on Amager Common is advancing rapidly

Who’s doing what?

Trains, ATC & operation:Ansaldo Trasporti

Civil engineering construction:Comet (Copenhagen Metro Construction Group):Tarmac Construction Ltd, Great BritainSAE International, FranceAnstaldi SpA, ItalyIlbau GmbH, AustriaNCC Rasmussen & Schiøtz Anl