THE German chancellor, Angela Merkel, will officially open on May 28 what German Rail (DB) describes as Europe's largest multi-level interchange station. The new Berlin Hauptbahnhof (main station) has been built on the site of the former Lehrter station, along with a new north-south link through the city centre and five new and upgraded stations in the Berlin area. Completion of this huge project will revolutionise rail travel in Berlin with major reductions in journey times and much-needed extra capacity. It also coincides with the opening of the Nuremberg--Ingolstadt high-speed line in Bavaria which will cut journey times between Nuremberg and Munich.

Berlin's unique history has had a major impact on the rail network. Prior to the second world war, Berlin - in common with London and Paris - was served by large terminal stations. However, Berlin also had an east-west elevated line known as the Stadtbahn with two tracks for mainline trains and two for the S-Bahn. All six terminal stations were severely damaged during the war, and while the Stadtbahn was also extensively damaged this was the only part of the mainline network in West Berlin that was restored. The construction of the wall around West Berlin in 1961 meant that the terminal stations were no longer needed as West Berlin was served by only a few so-called corridor trains running non-stop from West Germany. There were no regional trains operating through West Berlin. The wall also severed most of the radial lines serving Berlin. East Germany constructed a ring line around Berlin so that trains from cities in East Germany could reach East Berlin without passing through West Berlin.

The fall of the Berlin Wall in 1989 and subsequent German reunification meant that Berlin's mainline rail network was suddenly woefully inadequate for the steady expansion of long- distance passenger services and the introduction of regional trains. DB expects a 6 million increase in long-distance rail journeys to reach 19 million by 2010. While DB has not published any figures for regional passenger services, the separate S-Bahn network, which carried 320 million passengers last year is expected to carry 336 million by 2008.

Exterior view of Berlin's new Hauptbahnhof main station.

All mainline trains could only enter Berlin from the east or west, which meant excessively long journey times to cities to the north and particularly the south of Berlin, such as Dresden and Leipzig. Zoo, the main station serving West Berlin, only had two island platforms for long-distance trains. Friedrichstrasse in Stadtmitte, the old heart of Berlin, is similarly constricted. Berlin East (Ostbahnhof) and Lichtenberg stations are much larger, but too far east to become the main station for Berlin. None of these stations is able to address the problem of how to create a new north-south station and route through Berlin.

The solution adopted was the so-called mushroom concept because the route network looks a little like a mushroom. The idea was to connect the inner ring line to the north of the centre of Berlin, which already had the rights-of-way for main line tracks to exit Berlin to the north, with a new north-south line.

The northern part of the new line is in tunnel. Part of the tunnel parallels a new road tunnel beneath the Tiergarten and a new U-Bahn tunnel. The line surfaces near Yorckstrasse S-Bahn station and follows the track-bed of the former Leipzig main line to the south as far as the outer ring line where it links up with the existing rail network.

The tunnel passes beneath the Stadtbahn at the site of the former Lehrter station. There are two big advantages of using this location to build a new main station: sufficient space to build a new multi-level interchange, and the new station can be served by trains travelling both east-west and north-south. The new Hauptbahnhof is located to the north of the new parliament area and to the northwest of Stadtmitte in a rather desolate area of former railway yards. DB hopes that the station will act as a catalyst to develop the area. All that remained of the former Lehrter mainline station is an S-Bahn station on the Stadtbahn. To improve the situation, the new Hauptbahnhof will have a U-Bahn shuttle to Bundestag and later to the Brandenburg Gate, a new tram connection, and even a jetty for pleasure boats on the river Spree.

The scheme was approved in 1995 and a foundation stone was laid in September 1998. The project has involved the construction of a new six-track (two for the S-Bahn and four for mainline trains) elevated east-west line with three island platforms to the south of the existing Stadtbahn. This was completed in 2002 and trains were diverted onto the new tracks to allow the original section of Stadtbahn to be demolished. However, only S-Bahn trains have been stopping at Hauptbahnhof since then.

The station has been designed by the Hamburg architects Gerkan, Marg & Partners. A major objective has been to allow as much natural light to flood into the station as possible, even down to the underground north-south platforms, by using glass wherever possible. The east-west platforms are covered by a gently-curving single-span glass roof which rises to a height of 16m and is between 59 and 68m wide, and 321m long. The structure is secured in place by 85km of steel cable. Solar panels have been integrated into the glass panes over a 1700m2 section of the south-facing part of the roof to generate about 2% of the station?s power requirements.

The east-west platforms are 10m above street level. There is an intermediate level which contains a travel centre, a DB lounge, catering facilities, and shops. There are more shops and restaurants at ground level, along with links to public transport. Yet more shops and cafes are located one level below this along with an underground car park for 900 cars and 150 bicycles. In all, the station will have 80 shops covering 15,000m2, and all have been let. The north-south platforms are at the deepest level (15m below street level). Here, there are four island platforms for long-distance and regional trains, and one island platform for the U-Bahn.

An unusual feature of the station is the six panorama lifts connecting the east-west and north-south platforms and intermediate floors. Each consists of a glass-walled lift which moves inside a transparent tube. There are also 17 conventional lifts, nine lifts for use by the emergency services, and 54 escalators. The escalators and lifts were supplied by Kone and Otis.

Two office blocks running north-south flank the central area and arch over the station roof. These rise to a height of 46m. They are connected by so-called sky walkways. A 60m-high tower has been constructed beside the station to provide ventilation for the road tunnels.