Ground movement monitoring at King's Cross Station, London

Abstract

The redevelopment of King's Cross Station in central London includes the construction of a new Northern Ticket Hall and tunnelled connections to existing infrastructure. These works are to be carried out beneath a congested site including Grade I and II listed buildings, and heavy rail and road traffic both above and below ground (three London Underground lines). Arup and Soldata were required to design and implement a monitoring solution that would assist with the management of the risks. A direct and unique contract from the client to the instrumentation specialist was set up in order to keep a tight control on the data quality, and to ensure an optimal distribution of the results. A real-time system, based on an automated total station network combined with standard monitoring methods (inclinometers, precise levelling, etc.), was chosen. The detailed design and optimisation of such a system involves estimating the precision based on site-specific information. Since installation on site, the site monitoring data have shown the adequacy of the design, with the estimated field precision easily attained, and in some cases well exceeded. The main conclusion is that, with adequate care, the design and implementation of a large monitoring system can lead to fruitful results that are reliable, rapid and accurate.