The Chesterfield Canal Trust proposes that a new tunnel should be built at Norwood. This would go under the planned HS2 embankment as well as the M1 and run at the original tunnel level.
A Brief History
The original Norwood Tunnel was the most amazing feature on the Chesterfield Canal, which was designed by James Brindley. The tunnel opened in 1775 and was the longest in the world at 2880 yards, c. 1¾ miles.
Brindley’s original proposal was to build a much shorter tunnel of about 630 yards, but later he lowered it to form a longer top pound. Much of the final tunnel was only about 20’ below the surface.
There were always problems with the tunnel from subsidence – there are lots of mineworkings in the area. After decades of repairs, there was a major collapse in 1907 which was never repaired, so the western, Derbyshire, section has been cut off from the rest of the canal for over a century.
Like most canals, the Chesterfield Canal was in a sorry state by the 1960s, but was made a cruiseway from the River Trent to Worksop in the 1968 Transport Act. The then unnavigable section from Worksop to the Norwood Tunnel was classed as a remainder waterway.
The Chesterfield Canal Society, now the Chesterfield Canal Trust, was formed in 1976 and has campaigned ever since to get the canal fully restored. Thus far, 12 of the derelict 20 miles have been restored, along with 37 locks, 11 bridges and 2 marinas. A document called Next Navigation sets out full plans to get the remaining section of just over 8 miles restored.
Restoration reached the eastern portal of the Norwood Tunnel in 2003.
The major obstruction to full restoration has always been the Norwood Tunnel. Arup produced a report in 2008 proposing a route that would bring the canal up to the surface, going under the M1 via the Poplar Farm underpass. Amongst the problems with this route is the need to pump water to a very short top pound, which would have to feed a lot of staircase locks.
When the Government announced the change of route for HS2, moving it to just west of the M1 in the vicinity of Norwood, it became clear that the Arup proposal would prove difficult both for the canal restoration and HS2.
Building a newer, much shorter tunnel to the south of the original one would solve the water supply problem for the canal, because no pumping would be needed, and it would mean that the canal would be out of the way of the HS2 works if it was built before HS2 begins its construction.
The Chesterfield Canal Trust has spoken to Joseph Gallagher Ltd. about the practical problems and they have located a 4m diameter TBM which will handle mixed ground conditions and do the job.
The landowners on the eastern side of the M1, are supportive of the Trust’s work and initial enquiries have been made about the proposed plans. It is believed that agreements and land transfers could be agreed.
When the Arup report was commissioned and completed in 2008, and later the Next Navigation document, the priority of both was to confirm the viability of a restored canal and break down barriers to people and organisations who thought it to be impossible. This is why the conclusion was made that the overland option should be the preferred route. This route, whilst coming with many complications, appeared to be the simplest and therefore the most achievable.
The success of these documents in breaking down these barriers has changed perceptions of the possibility of canal restoration from ‘if’ to ‘when’.
The focus of the Chesterfield Canal Trust now is not just to restore the canal from West Stockwith to Chesterfield, but to restore it in a way that it can be maintained and enjoyed by people for at least another 250 years. The long-term maintenance and liability costs for the overland route would be very onerous on any navigation authority. This has been highlighted by the current era of austerity. Any organisation in the future, whether local authority, charity or other, may struggle to meet these obligations.
With such a sensitive water supply and short top pound, there is a risk that, in time of drought, the canal could be closed again across its apex at what should be its busiest times for visitors and pleasure boaters.
The benefits of the New Norwood Tunnel proposals are:
- 9 fewer locks to build and maintain.
- No requirement to adapt the M1 viaduct.
- No requirement for a viaduct at the HS2 crossing.
- No requirement for an occupation bridge at Coalpit Lane.
- No requirement for a PROW bridge at the Western Portal.
- No requirement for Ground Water Extraction.
- No need to construct and maintain 600m of open cut canal.
The biggest obstacle to the New Norwood Tunnel is the capital expenditure required to construct it. This is thought to be outweighed by long term maintenance and repair costs with a return period expected to be less than 60 years.
Initial technical and construction advice has been sought from a contractor experienced in this field. The belief is that Highways England would only accept a tunnel boring machine style method to ensure there was no impact or risk to the operational M1 motorway.
The new tunnel is proposed off line from the original to avoid the existing tunnel lining, made ground and original air shafts (now backfilled). The proposed tunnel would be blatantly new, utilising new construction materials, so that tunnel users are aware that this is not the original Brindley tunnel but a 21st Century replacement. The story of the original tunnel would then be interpreted so that this nationally important heritage feature will be recognised once again.
The new western portal would be sited adjacent to the original, again to aid with heritage interpretation, and at the same water level. This would maintain the impact of the Norwood Flight, an original set of 13 locks over three triple staircase locks and a quadruple staircase lock immediately to the West.