Cover image from TDNS document

Decarbonisation

Network Rail have published their Interim Programme Business Case for the Traction Decarbonisation Network Strategy (TDNS). The title may appear dull, but the implications are anything but:

Although rail contributes less than 1% of the total UK annual greenhouse gas emissions it is in the unique position of currently being the only transport mode capable of moving both people and heavy goods using a zero-carbon solution. As a result, rail has a huge potential role to play in decarbonisation of the UK economy by providing reliable, green transport for goods and people.

TRACTION DECARBONISATION NETWORK STRATEGY – Interim Programme Business Case – Executive Summary

This 257-page document sets out the business case for removing diesel-powered trains from the network. Its objectives are to get rid of all diesel-only passenger trains by 2040, and all other diesel passenger trains (for example hydrids and dual mode) by 2050. In Scotland the target is to achieve this by 2035.

Choice of technologies

Three technologies have been identified:

For high speed long-distance services and significant freight flows, 25kV overhead electrification offers the best solution. Other routes and traffic flows may be more effectively served by battery trains, hydrogen trains, or some combination of technologies.

The size of the electrification task is measured in single track kilometres (STK). This gives the total length of track in a given section of route, so 1km of double track railway is 2 STKs.

15,400 STK of the rail network is currently unelectrified. Of this, the strategy proposes that 13,000 STK is electrified, 1,300 STK is operated using hydrogen trains and 800 STK using battery trains. This leaves 300 STK for which no decision has been made.

The strategy also proposes that any extensions to the network should ‘consider the need to operate using zero-carbon rolling stock’, and recommends ‘Continued support for projects and programmes which increase capacity or provide a step-change in capacity to support modal shift’.

What does this mean in our area?

Most lines in the Bristol area are indicated as ‘core electrification’. This means 25kV overhead electrification from Chippenham to Bristol Temple Meads and Filton Bank, as well as the main lines to Birmingham, Exeter and Southampton. It covers all the MetroWest lines, although Severn Beach (along with the Barnstaple, Exmouth and Newquay branches) is indicated as ‘Multiple (Proposed Electrification)’, meaning that it would probably be overhead 25kV but that other technologies could be used.

A relatively short length, but well-utilised, commuter service operates from Severn Beach to Bristol. This service could be operated using battery traction, however, given the relatively short distance involved and the potential to improve resilience and a diversionary route for freight from Severn Beach this route may benefit from electrification. Electrification would also benefit the containerised waste services which operate over this route, between west London and the waste-to-energy plant at Severnside, near Severn Beach.

TRACTION DECARBONISATION NETWORK STRATEGY – Interim Programme Business Case – Page 232

The Weymouth line is indicated as ‘Multiple (Proposed Battery)’, and the short Cornish branches are seen as suitable for battery operation.

When will this start?

The strategy is looking at a 30-year rolling programme, and assumes that the obvious benefits of setting up a stable and continuous supply chain are seen.

The West of England Combined Authority is developing the Metrowest proposals which will entail significant service enhancements for Greater Bristol, many of which could exploit the future electrification of these routes, including introducing passenger services to the Henbury branch of the Severn Beach line.

TRACTION DECARBONISATION NETWORK STRATEGY – Interim Programme Business Case – Page 200

With the support of WECA, we might hope that the Bristol area will be looked at early in this timeframe. Quite a lot of preparatory work has, after all, already been done.

Image: Network Rail

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