Alternative Cornish rail route fails value for money test

A  Network Rail report commissioned by the government earlier in the year to investigate an alternative rail route to Cornwall and Devon (to by pass the disaster-prone Exeter-Newton Abbot section) has resoundingly concluded that all options examined represent very poor value for money.

The report was in response to the part demolition of the Dawlish sea wall and other storm damage wreaked on the GW West of England main line in February. Its findings will be inputted into Network Rail’s long term planning process, and will be incorporated into the western route study.

Network Rail is committed to keeping the Exeter -Dawlish-Plymouth line open, but wants an alternative route to safeguard against future stoppages and disruption. Coastal erosion, cliff collapse, estuarine flooding and rising sea levels pose growing challenges, and the section between Exeter and Newton Abbot is particularly badly affected.

‘Very poor vfm’ in DfT parlance means any project with a BCR (benefit: cost ratio) of less than one. The schemes examined were all well below this level, and each one turned in negative net present values (NPV) as well. The economic appraisal assumed that construction would start in 2021 for 2026 completion with operation commencing in the following year. Values for costs and benefits were calculated over a 60 year period; 2014 prices have been used.

A number of sensitivity tests were conducted to vary the scenarios, but these had little impact on the overall negative results.

Network Rail costed the various alternatives: maintaining the railway as at present (the base case, cost £0.8m plus £5m every  five years); strengthening the defences of the existing line( between £398m and £659m); re-opening the former LSWR Exeter to Plymouth route (£875m); re-opening the Teign Valley line via Heathfield (£400m); and building a new line (with five different routes to chose from costing anything  between £1.5bn and £3.1bn).

Re-opening the LSWR line would be far from straight forward: A new Meldon viaduct would have to be built as the existing structure is badly deteriorated; eight miles of line need raising in places to avoid flood damage; the route is sharply graded (1 in 75), the trackbed has been partly built over and the structures would require clearance for future electrification. Through trains would also need to reverse at both the Plymouth and Exeter ends, adding an extra 14-20 minutes to journey times.

The Teign Valley line suffers from the drawback that it was built as a single track railway and would have to be widened; it would offer the lowest running speeds (mainly 45-50mph) and add an extra seven minutes to journey times; considerable lengths lie in a flood risk area, and it has little intermediate traffic.

Strengthening the existing line via Dawlish would entail fortifying the sea wall, installing rock armour, raising the railway and improving flood water flows.

The new construction would involve building inland to cut out the worst bits of the Exeter to Newton Abbot section; all five routes offered time savings (of between three and six minutes) but  two still had some element of flood risk.

 

NPV (£m) BCR
LSWR re-opening -813 0.14
Teign Valley re-opening -346 0.29
New build: Alphington to  Ware Barton -2.572 0.08
New build: Exminster to Ware Burton (western) -1.995 0.12
New build: Exminster to Ware Barton (eastern) -1.755 0.13
New build: Exminster to Bishopsteignton -1.157 0.17
New build: Dawlish Warren to Bishopsteignton -1.134 0.15

 

652/Jul 14

 

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