Local authority civil engineers in Berlin have had the time of their lives in the 1990s. They have played a central role in reunifying the city's divided transport infrastructure following the removal of the Berlin Wall in November 1989. Budgets swelled as extra central government funding for reunification projects became available.
For 28 years the Wall cut across the centre of Berlin and surrounded the western part of the city, isolating it within what was East Germany. Erected suddenly by the Russians in 1961, crossing the Wall was cumbersome. Motorists had to pass slowly through checkpoints, making east-west road traffic almost non-existent. Bus travel was out of the question.
Rail was easier as some of the city's east-west underground and urban rail lines remained open. But other east-west lines were deliberately severed. Most people crossed the Wall on foot or by train and had to go through time-consuming passport and visa checks.
When East Germany collapsed in November 1989, the Wall and its border controls were dramatically removed. This created an immense challenge for the city's construction and housing department. Its engineers suddenly found themselves under pressure to reopen roads and bridges which for decades had been cut off by the Wall and left to decay.
Almost overnight Berlin's engineers had to decide which road links should be revitalised first.
'Suddenly 1.7M east Berliners wanted to come to west Berlin,' says housing and transport department engineer Peter Weyer. 'People were going from east to west for 20 hours a day.'
Weyer's department had to work flat out to reopen cross wall routes to cope with Berliners eager to try out their new-found freedom.
This was not easy. 'Most of the road bridges to east Berlin were interrupted and were in a terrible state,' Weyer says.
Twelve of the main routes were bridges over the River Spree, along which the Wall ran. These needed rapid structural inspections before they were considered safe to use.
Even then, most were limited to pedestrian use for fear that cars and lorries would make the decaying structures collapse. In the end half of these bridges had to be replaced as they were considered beyond repair.
The other main priority was to repair streets and road bridges in east Berlin. In total, the city government has now repaired 250 out of 400 bridges. Neglected under the old regime, structures in the east had begun to crumble and roads were typified by potholes and poor drainage.
Since 1989 the city has spent about £20M annually in its effort to repair and reunify the city's transport infrastructure.
It is also building the new £243M north-south road tunnel through the new parliament area and under the environmentally sensitive Tiergarten park. This is intended to improve north-south road links across the city centre (see box).
Most of Berlin's east-west road links have now been restored and in the central area around the Brandenburg Gate traffic flows relatively freely.
Perhaps the biggest transport obstacle in the centre of Berlin today is the huge volume of construction work going on around the Reichstag and Potsdamer Platz, areas which used to straddle the wall. Here roads are either blocked or temporarily diverted on an almost daily basis.
This aside, Weyer believes that Berlin's inner city transport network has again begun to function normally with people travelling to work from west to east and vice versa.
He says that if anything some roads in the eastern part of the city are now in better condition than those in the west.
Despite the scale of the city's construction programme, Weyer claims that his department managed to keep a lid on its costs. He says that the fierce competition for work which has typified the German market in the 1990s kept its construction prices down.
'In some parts the costs were higher than planned, but in several cases some of the bridges were cheaper,' Weyer says.
Running parallel with the re-establishment of the roads network in Berlin has been £6.6bn programme to revitalise the railways. This work was financed by rail utility Deutsche Bahn.
Grim east Berlin stations like Alexanderplatz and the Hauptbahnhof have already been modernised with new escalators and shopping areas. Others like Friedrichstrasse are in the final stages of reconstruction.
Previously severed urban S-Bahn lines have also been re-established, notably between the eastern junction and station at Ostkreutz and western Neukoln.
An inner S-Bahn circle is now approaching completion north of the centre. This will revive 17km of track around the northern suburbs and include construction of a new interchange at Nordkreutz, between the west Berlin station of Gesundbrunnen and the east Berlin station of Bornholmerstrass. The southern half of this ring is already finished.
Now east-west links have been restored, the city government's attention has switched to focus on improving connections between inner Berlin and the outlying countryside.
Western Berlin is especially poorly served in this respect. During the cold war it was completely sealed off from East Germany and many road and rail lines were destroyed at the Berlin/Brandenburg border.
Even now there are a limited number of strategic routes out of west Berlin. These often switch suddenly from dual to single carriageway as they cross into Brandenburg, causing long traffic jams during peak times.
Such links will need a huge amount of investment and already the government has started showing signs of balking at the massive cost of some new schemes.
This autumn the city expects to start on work on a motorway connection from the inner ring road to the main Berlin to Dresden motorway - a project which alone is expected to cost about £530M.
As a result other major projects, such as the city's plan to complete the eastern half of the A100 inner autobahn ring, are unlikely to go ahead in the foreseeable future.
The western part of this is mainly complete and contractors are currently building a 4.3km extension including a 1.4km cut and cover tunnel between Tempelhof and Neukoln in south-west Berlin.
But the eastern half of the ring looks more problematic. East Berlin is heavily built up, so extending the route would either involve costly tunnelling or disruptive upgrades to existing streets. Weyer's team is expecting a long battle with the German finance ministry before the project can be built.