Queensferry Crossing Network Connections
The Queensferry Crossing was built alongside the existing Forth Road Bridge and carries the M90 motorway across the Firth of Forth between Edinburgh, at South Queensferry, and Fife, at North Queensferry.
Sweco was commissioned for the design of road network connections to the new Queensferry Crossing over the Firth of Forth, Scotland, including 6.4 km of new or improved motorway standard dual carriageway and significant modifications to the local road network.
This was a major earthworks operation. Measures we implemented to reduce waste and maximise soil/rock reuse included the following.
- The c. 380,000m3 recycled aggregates won from local spent oil shale stockpiles (by-product of the local shale oil industry) and c. 120,000m3 of locally sourced dolerite.
- The re-useable portion of former landscape fill and other made ground materials (cobbles and boulders of dolerite) were separated and crushed prior to re-use as Class 1 or Class 6 fill.
The Result and Benefit to the Client
Significant cost savings were achieved on the scheme by utilising the spent oil shales, which were also used to construct the Ferry Toll embankment; in doing so reducing the span of the new Ferry Toll viaduct allowing more savings to be made.
To achieve cost savings of tens of millions of pounds, the original seven-span design for Ferrytoll viaduct to the north of the crossing was challenged by proposing an alternative twin-span solution. In its place innovative ground improvement techniques, including Controlled Modulus Columns (CMCs) and Trench Mix hybrid were utilised to support an earthwork alternative. On the northern network connection, the B981 (originally designed to be supported by a piled load transfer platform) was constructed over CMCs adding to the significant saving in both cost and programme.
Sweco was a finalist at the Ground Engineering Awards for our work on this project.