INTRO: Construction work to rebuild Berlin’s main line and S-Bahn networks is forging ahead at a furious pace. Murray Hughes reports from the site of Berlin’s future inter-city interchange

VISIT THE east end of the S-Bahn platforms at Lehrter Stadtbahnhof in the centre of Berlin, and you will see and feel the frantic pace of construction activity that will radically alter the city’s already extensive rail network. Go at night, and the daylight impression of mud, cranes and bulldozers becomes a surreal vision of floodlit machines taking over the city. Work is going on round the clock as contractors strive to meet the government’s completion deadline of 2002.

Look to the north. Two huge blue bucket wheels are scooping up gravel in a confusing web of pipes, conveyor belts and water channels. Sand and gravel hoppers fill and empty among banks of yellow cement silos. The air is full of the clink of gravel on metal, the rush of water and the hiss of conveyors.

Look south. A brightly-lit crane forest looms out of the dark, with the mechanical arms of excavators moving eerily below. Water reflects the lights of distant buildings. The scurrying ants are men.

Here at Lehrter they are building the foundations of Berlin’s biggest interchange. It is sited at the intersection of the east-west Stadtbahn and a completely new north-south tunnel passing right under the city’s famous Tiergarten. It is the keystone in an ambitious programme to restore the city’s rail network to its pre-war state, with the addition of the north-south trunk line. When the programme is complete, Berlin will enjoy unrivalled rail links to the surrounding region and the rest of Germany.

Around DM20bn is being poured into Berlin’s rail network under a programme of works being managed by DB Projekt GmbH Knoten Berlin, a dedicated project management subsidiary. About 200 separate projects are under way, so co-ordination and punctual completion of individual schemes are vital to avoid delay. Many of these require close co-operation with outside agencies or companies such as Sony, which is building its European headquarters at Potsdamer Platz.

The mushroom

The projects designed to improve flows of long-distance traffic dovetail into what Berliners have come to know as the mushroom concept which will absorb around half of the DM20bn.

The name stems from the shape of the network of new lines (map p381). The cap of the mushroom is formed by the North ring linking main line arteries in the west, north and east with the new north-south cross-city route. This entails rebuilding 78 track-km and renovating or constructing 154 different structures including two platforms for long-distance trains at Gesundbrunnen.

The rim of the mushroom is formed by the east-west Stadtbahn. Work has been in hand for some time to rebuild the 8·8 km elevated section from Zoologischer Garten to Hauptbahnhof. This carried two S-Bahn tracks electrified at 750V DC third rail and two unelectrified main line tracks. On completion of rebuilding, these will be wired with DB’s standard 15 kV 16·7Hz catenary.

Originally considered to be a track upgrading job with some work on the formation and structures, the Stadtbahn work has turned out to be a complete rebuild with whole sections of the formation and old bridges demolished and replaced. A continuous reinforced concrete slab 18m wide and 250mm deep is being built along the whole route to ensure even weight distribution and to permit the space under the railway to be used again for commercial premises. New drainage is being installed and 48 bridges replaced.

Renovation of the two long-distance tracks began last August, and S-Bahn trains began running on newly laid slab track in October.

The mushroom’s stalk consists of a 9 km main line link starting near the Landwehrkanal in the south and finishing at a major junction with the North ring some distance north of Lehrter station. The central section runs in four separate tunnels for 3·5 km. Major interchanges will be provided at Lehrter, Potsdamer Platz and Papestrasse, giving passengers unprecedentedly good access to inter-city services, S-Bahn routes and regional trains. Apart from passing below the Tiergarten, the route also dives under the River Spree, which has been diverted while work takes place.

S-Bahn renovation

DB Projekt GmbH Knoten Berlin is also in charge of the programme to renovate the city’s extensive S-Bahn network. Reconstruction of the sections in West Berlin that were closed after the Wall divided the city in 1961 is a huge task.

Gaps are being filled in the network so that the inner ring is once again complete: Westend to Schonhauser Allee in the north and Treptower Park to Neuk