Railway Tunnel Monitoring

George & Campbell Streets Sydney

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JBW commenced work on this property on the corner of George & Campbell Streets Sydney in October 2006.

This work included carrying out a survey of the property boundaries and the location of the railway tunnels under the future building, as one of the major constraints in developing the property were the two tunnels for the Eastern Suburbs Railway (ESR).

The proposal for the site was to construct a mixed use high rise building of approximately 40 levels with retail and commercial components on the lower levels and residential units in the higher levels.

Apart from establishing accurate survey control through the tunnels from Central to Town Hall railway stations a laser scanner was used to survey the existing tunnels, including the inside face of the walls of the tunnels, the position of the rails and the position of any rail infrastructure such as signalling and switches.

In early 2010 JBW was commissioned to design, implement and manage a tunnel movement monitoring system, which satisfied the conditions of the Tunnel Monitoring Plan imposed by RailCorp.

A key element of the Tunnel Monitoring Plan was that there was to be no disruption to trains for the ESR, which meant that all work within the tunnels was carried out between 1am-4am or during infrequent maintenance shutdown periods.

High accuracy monitoring of the tunnels was carried out to an array of 100 monitoring prisms installed by JBW in the railway tunnels, for the duration of the construction period of approximately 18 months.

Most of this monitoring work was carried out from permanently installed, high accuracy robotic total stations which were controlled from a remote work area on the Town Hall railway platform approximately 500m from the monitoring zone.

In addition to the target movement monitoring reports that came natively from the GeoMos software, JBW had to extract data from the GeoMos SQL databases and then apply complex mathematical calculations to that data to create specialised complex reports required for the Tunnel Monitoring Plan.