Mersey Gateway Project
The Mersey Gateway brings much-needed traffic relief for the existing Silver Jubilee Bridge and leads the infrastructure investments required to deliver regeneration of Halton and the North West.
More than 80,000 vehicles use the Silver Jubilee Bridge every weekday – ten times the number it was originally designed for. This extra traffic puts the congested and ageing Silver Jubilee Bridge and the resilience of the regional road network under severe pressure.
The new bridge is designed to carry up to six traffic lanes forming part of a new and improved high standard road (9.5km long) connecting north Widnes and Merseyside with Runcorn and the national motorway network in north Cheshire.
The design of the new Mersey Gateway Bridge is based on a cable-stay structure similar to the second Severn Crossing, but with three towers. It will be 2.3km long with a river span of 1km. The main bridge deck will be made from reinforced concrete and the spans will be supported by steel cable stay.
- Mersey Gateway Project
- 2015 ongoing
- Halton Borough Council
- Mersey Link Consortium
- Instrumentation Specialist
- Stuart Well Services
Construction of the three main bridge pylons piers involves forming three circular cofferdams at the North and South banks and the centre of the river. The distance from the North to the South bank cofferdams is approximately 400 metres.
Within these cofferdams the ground will be excavated to form the foundation of each pylon. In order to maintain stability of the cofferdams, measurement of the groundwater level is used to demonstrate the effectiveness of the dewatering system.
At each cofferdam, multi-level vibrating wire piezometers were installed in boreholes to monitor groundwater profiles during construction. The VW piezometers were connected into a series of multi-channel Wi-SOS 480 wireless nodes, all of which connect by 800MHz wireless to the Wi-SOS 480 Gateway. The Gateway uploads all data from the VW piezometers via GPRS to the Wi-SOS 480 web portal which can be accessed via the Internet. Prior to that base-line readings were taken using an MP12 portable readout.
The Wi-SOS 480 is a star network based on 800MHz low frequency which has the capability to read nodes over distances up to 10km.