Deformation Monitoring of the Underground Metro Station Rotterdam CS: A Case Study

The increasing pressure on public transport has resulted in the development of several mega projects in and around the Rotterdam Central Station area. At the moment this area is being transformed to a modern public transport hub. One of the projects is the expansion and upgrading of the existing underground metro station. The building activities during the first phase of the project were executed very close, up to 1 m, from the existing metro station. The probability of causing deformations to the metro station was therefore very high. The contractor put a monitoring system in place consisting of a robotic tachymeter in combination with tilt meters. The monitoring system was working continuously, the monitoring results were presented on-line using an internet application also providing the on-line check on the hazard warning levels. The most prominent risk, interference of operation of the metro station, did not occur. Full accessibility of all services was maintained during all building activities. The monitoring system operated according to contract specifications. The on-line presentation and checking on hazard warning levels was very helpful in detecting the effect of building activities on the metro station. Monitoring has been used successful to control building risks. As a result of refraction problems, a system with more internal control was recommended for phase 2 of the project. The monitoring specifications for phase 2 were set up with two tachymeters in combination with crack meters placed over the station section joints.