Case Study: Rodney Street
Consultant: Donaldson Associates
In Edinburgh, Ritchies strengthened an old railway tunnel as part of the Sustrans National Cycle Network. Sustrans is constantly reviewing the status of the National Cycle Network and is working with local authorities and other partners to bring all sections of the network up to standard. The Rodney Street project at Canonmills was part of this programme.
The tunnel was originally built to carry trains to the Granton Ferry before the Forth Road Bridge was built. The rail line was closed in 1968 and the area beneath the tunnel was partially infilled. As part of the development of the National Cycle Network, Sustrans is reopening and strengthening the tunnel to make it safe for use by cyclists.
The future aim, in partnership with the council, is to use the tunnel, as part of Route 75, enabling cyclists and pedestrians to avoid the busy road junction that sits above it.
Prior to any works being undertaken, traffic management reduced live traffic above the section of tunnel to be lined to a single carriageway. Cover to the tunnel crown is only 300mm and road levels were surveyed to monitor any potential settlement.
The strengthening works were undertaken in two phases to coincide with the traffic management regime. Each phase comprised:-
- Daily monitoring of road levels, excavation of backfill, application of initial steel fibre reinforced sprayed concrete, fixing of 2 layers of steel reinforcement, application of 400mm sprayed concrete.
- The final works of a layer of polymer fibre reinforced sprayed concrete applied to the whole area to provide fire resistance.