|Image:||Marcel van der Burg|
Zwolle train station
The pedestrian tunnel is part of a larger transformation and expansion of the train station, which includes new canopies above the platforms, to accommodate the increased train traffic, particularly since the arrival in 2012 of the direct fast connection to Amsterdam. For this purpose, an additional platform was built, to serve the extra tracks. Right now, Zwolle is the second-largest railway hub of the Netherlands.
This added to the complexity of the building project, because all interventions had to be realised while this busy station remained in full use almost all the time. The first stage was digging out and constructing the tunnel itself under the existing tracks. A significant part of the tunnel is below groundwater level, which required both drainage and waterproofing. The most innovative, and daring, part of the building process was the actual construction of the large decks bearing the tracks. These four decks were first made on a building site right next to the station. Within a short period of interruption of all train traffic for nine days, the decks were transported through the tunnel to their final location. The concrete decks, with a weight varying between 1,000 and 1,400 tons, were wheeled in on huge, self-propelled transporters of the kind that are used to move large and heavy parts at shipyards