Exclusive: ECML tunnels to be opened by Private Sector

Private sector to break Welwyn bottleneck

Eye understands that Treasury is close to signing a significant deal on ECML capacity enhancement, involving private sector finance.

The ECML’s greatest capacity limitation is the two track section at Welwyn North. In 2000 Railtrack proposed widening the viaduct and boring new tunnels to provide four tracks throughout, and Eye understands Provisional compulsory purchase orders were put in place.

With the demise of Railtrack these schemes lapsed and the 2000 plan is now, of course, seen as politically unacceptable, not least by local MP Michael Green.

An internal NR document seen by Eye headed - Project: Rail-Loop (F) - which has already cleared most GRIP stages, proposes Welwyn North Base Tunnel (WNBT).

Engineering studies are believed to suggest a tunnel built to the same maximum 2.5% gradient specified for HS2 would be both feasible and less intrusive. As well as an acceptable alternative to doubling the viaduct plus second tunnels parallel to the existing bore.

The document says:

"Within the HS2  parameters the 1.4  mile ramps would  place the southern portal of the WNBT on the disused sidings to the East of Welwyn Garden City station.  At its deepest the tunnel would run some 25 metres, below the surface of the Mimram Valley and the viaduct, before climbing to the surface and joining the existing ECML alignment beside the North  portal of the existing tunnel near  Woolmer Green Junction. At Crossrail speeds tunnelling would take around a year."

Eye understands that final sign off from Treasury and DfT on WNBT is dependent on Chris Gibb’s review into  the 2018 Thameslink timetable. As the proposed Thameslink TT renders EMT and VTEC service enhancements almost undeliverable additional capacity is desperately required.

The construction of WNBT would be independent of the existing railway aside from the connections at each end.  Making an ideal candidate for private finance, attractive to both funders and existing consortia, especially those with suitable tunnelling machines released from current schemes.

Operational benefits would include separation of local and Thameslink services from long distance trains. Depending on the speed in the new tunnels there could also be a slight reduction in journey times.

DfT and NR were unable to comment.