Summary of Network Rail report July 2014 by Alan de Burton
Bad weather damage closed the West of England route between Exeter and Newton Abbot for 8 weeks in February and March 2014, the longest interruption of service since the line was opened in 1846. The overall cost was estimated to be in the order of £40m – £45m. The government asked Network Rail to compile a report on the future route options, which I have summarised here.
Summary of Options and Conclusions
Option 1: Base case: continuing current maintenance
Option 2: Further strengthening of present route over four Control Periods (i.e. over 20 years at a cost of c. £30m p.a.)
Option 3: Reinstate former London & South Western Route via Okehampton (£875m including 66% contingency uplift)
Option 4: Reinstate former Teign Valley route Exeter – Christow – Heathfield – Newton Abbot (£470m including uplift)
Option 5: New routes from various points west of Exeter to Newton Abbot (in range £1.49bn to £3.10bn)
Risks with present coastal route
Network Rail divide the risks of the present route into 5 sections as follows:
Exeter to Dawlish Warren: estuarine / river flooding. This section is mainly protected by the Environment Agency. Climate change with higher rainfall may further increase the risk in future
Dawlish Warren to Teignmouth: this is divided by Network Rail into 3 sections but all share risks of higher seas / marine erosion, rockfalls, cliff stability / failure and landslides
Teignmouth to Newton Abbot: as for Exeter to Dawlish Warren
The route is used by 134 passenger trains per day (both directions combined) and 2 freight trains, no doubt the busiest it has ever been all year. The population served by the line has increased by 7.3% since 1997 and passenger numbers have been rising rapidly.
Option 1: Base case
Recent expenditure has been of the order of £0.8m per year but the engineering cost of the early 2014 disruption was £24m. The route is now obviously not adequately resilient for the future.
Option 2: Further Strengthening of Present Route
Network Rail are still working on the detail. There are a wide variety of works depending on location. On the estuarine sections, it includes raising embankments, constructing flood relief culverts and new viaducts to let out floods and raising Environment Agency defences. On the sea wall section between Dawlish Warren and Teignmouth where the responsibility rests with Network Rail works are needed on both sides of the railway. On the sea side, the sea wall needs to be strengthened and protected by shoreline rock armour, offshore rock armour and berms parallel to the sea wall. On the cliff side, it includes attending to cliff instability by rock bolting, netting, retaining walls, slope drainage and ‘resloping.’
The timescale is of the order of 20 years because of the continuous need to run trains so the work cannot be seriously speeded up without major disruption to train service.
Option 3: Reinstate former London & South Western Route via Okehampton
This route is still open from Exeter to Okehampton but largely as a single track not in Network Rail ownership, and from Bere Alston to Plymouth as a single track with passenger service. On the closed section between the track has been removed and the trackbed sold. However, the only major obstructions on the trackbed are extensive building developments in Tavistock. A new viaduct parallel with the old would need to replace the original and now life expired Meldon Viaduct west of Okehampton.
There are a number of major engineering and operational problem. Although the route was previously double track, the trackbed doesn’t meet modern minimum engineering standards; the trackbed isn’t wide enough especially for maintenance access and the line was built before modern knowledge of soil mechanics. Many slopes would have to be eased and drainage improved. In particular, about 13 kms at the Exeter end in the valley of the River Creedy would have to be extensively rebuilt because of high flood risk, also blocking the Barnstaple route while performing this work.
The operational problems are twofold. Firstly, except for ‘route knowledge’ workings the line is unsuitable for through trains from east of Exeter to Cornwall because about 15 minutes would be lost, mainly in reversals at Exeter and Plymouth. Secondly the reinstated local service wouldn’t cover its operating costs. You could save about a quarter of the cost by copying the Borders Railway in Scotland and resurrecting only single track with long loops; however you would then need to replace the local service by buses when main line trains needed to run on diversion from the coastal route.
Option 4: Reinstate former Teign Valley route Exeter – Christow – Heathfield – Newton Abbot
This would be a much more difficult and unsatisfactory task that reviving the Okehampton route. The line was originally built as no more than a rural branch line with a poor alignment, heavy gradients and level crossings; it was completed as late as 1903. The site has been heavily built over in places and part of the alignment used as a road. The two tunnels were only built for a single track, and one of these has collapsed. The most sensible engineering solution would be to construct a new tunnel 1.5 kms long. Since the local population is limited, Network Rail see no scope for any new stations or intermediate traffic. Although Network Rail don’t quite say so, this solution is in the ‘no hoper’ category.
Option 5: New routes from various points west of Exeter to Newton Abbot
Network Rail identified about 20 possible options, but consolidated them to 5 for the purposes of the study. The prime differences between them are whether or not the routes avoid the estuarine sections from Exeter to Dawlish Warren and from Teignmouth to Newton Abbot. The Great Western Railway faced the same dilemmas in the 1930s. While they acquired parliamentary powers for one scheme in 1936, after flooding on the Exeter to Dawlish Warren section they changed their minds and secured authority for a revised scheme in 1937. Because of WW2, the scheme was abandoned. While all the schemes will save about 5 minutes for non-stopping trains, they are all vastly expensive because of the amount of tunnelling involved avoiding the coastal route from Dawlish Warren through Dawlish to Teignmouth.
The Benefit / Cost Ratio of all the options on new route is between 0.08 and 0.29 whereas the government normally won’t consider anything below 1. Even making heroic assumptions on greater rail traffic and reduced construction costs won’t bring much benefit. Although the report doesn’t quite say so, Option 2 strengthening the present route beats all the alternatives in expense and practicality by a wide margin. Network Rail will undertake further work on the engineering for its future Western Route plans.