Monitoring the Network Rail Tunnel at Central Village, Liverpool

Monitoring the Network Rail Tunnel at Central Village, Liverpool

About This Project

Client Requirement

Central Village is a mixed-use venture under construction in Liverpool, near Central Station. It consists of a 25 and a 20 storey building linked by a nine storey residential and commercial podium, and two nine and five storey buildings for residential, hotel and commercial use. The development will cost £160 million.

The construction of the multi-storey car park and the new Network Rail (NWR) office facilities required demolition in the area of the NWR Central Line tunnel, which feeds into Central Station. The planned excavation and piling works required the contractors to determine whether the structure was stable and safe by monitoring the potential and actual movements of the adjacent Network Rail tunnel, walls and ceilings.

Solution

Murphy Surveys completed a Laser Scan survey of the tunnel, and used the as-built data collected to design a monitoring solution. The installation of the solution was carried out over a period of approximately two weeks, during engineering hours (00.00am to 04.00am), and included the following:

– A network of multiple wall-mounted GeoRobot survey stations and 180 targets with accuracy of +/- 0.5 mm in the vertical plane +/- 1 mm in the horizontal plane.

– 120 Electro Level Beams whose combination with fixings and the associated data loggers provided accuracy of 0.1mm in horizontal and vertical deflection.

The primary system of monitoring the tunnel movement utilised Electro Level Beams installed longitudinally along the lining of the tunnel, whilst a secondary independent system consisted of a series of four-point arrays of 3D geodetic prisms fixed to the tunnel walls and roof, monitored using total stations. Vibration monitoring of the tunnels was carried out using a series of geophones in areas where proposed piling works may have introduced higher levels of vibration to the existing tunnels.

Client

McGee

Survey Type

3D Laser Scanning
Monitoring

Sector

Transport

Duration

1 Year

Equipment

Laser Scanner
Automated Total Station
Electro Level Beams
Vibration Sensors

Category

Case Studies, Laser Scanning & BIM, Monitoring, Rail, Survey & Engineering