The problem of road congestion on the A605 road, resulting from increased rail traffic through the Kings Dyke level crossing, needed an ambitious diversion scheme that involved a new road and bridge, rail works, ground works and landscaping.
The bottleneck at King Dyke
Overall, the level crossing between the A605 Peterborough to Whittlesey road and the railway line between Peterborough and Ely was a bottleneck causing significant journey time unreliability. This constrained the planned growth of Whittlesey in terms of being an attractive place to live and work.
Local people had been looking for a solution to the problem for a long time, which had been getting worse:
- Every day, before the start of the scheme, there were an estimated 12,000 vehicles using the A605 between Whittlesey and Peterborough, and 120 train movements across the level crossing.
- The level crossing barrier downtime took place between 8 and 25 minutes in any hour. It was controlled locally controlled by an on-site Network Rail employee.
- Future plans by the rail industry to increase the number of movements along the line could see the number of trains using the crossing increase.
- In winter months the situation was exacerbated because local flooding caused the only alternative route into Peterborough via the North Bank to be closed for long periods of time. This put an additional 5,000 vehicles a day through King’s Dyke and doubled the average delay per vehicle.
In 2017 Ramboll was successful in a submission with Kier for a £16.5m improvement scheme for Cambridgeshire County Council. With building starting in early spring 2019 and completion in late 2020, the design of the diversion scheme involves:
- Diversion of a 1km length of the existing A605 Peterborough Road with a new road bridge over the railway
- Significant earthworks and ground stabilisation to carry the new road over very soft ground and along the edge of a steep sided disused clay pit.
- Construction of an underpass allowing a local landowner to continue accessing land both sides of the scheme
- Closure of the existing Kings Dyke level crossing
- Rationalisation of multiple accesses to local commercial and residential properties
- Improvements to road safety in the area
Ramboll is designing bridges, rail, infrastructure, roads, landscaping and environment, and ground engineering for the scheme.
The earthworks are an important part of the scheme and involve:
- Managing up to 2m of ground settlement by improving peat and very soft soils
- Designing the embankment adjacent to the disused clay pit
Initial works included interpreting the existing ground investigation (GI) information, undertaking embankment settlement assessments, developing ground improvement options, undertaking retaining wall design and developing proposals for further GI.