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Electrifying the Marlow Branch

Obstacles and Opportunities

A personal view by Richard Porter

We now know that the off-on-off electrification of the Marlow branch line is definitely off the agenda for the duration of the current Great Western Railway direct award franchise which runs to 2019 with a possible one year extension. Electrification of the Bourne End and Marlow lines in Control Period 5 (2014-19) is explicitly ruled out in the update to the Hendy Report.

Why Electrify the Branch?

  1. There’s the well-known Sparks Effect - when you electrify a line more people use it because it is seen as being cleaner and greener, quicker and quieter.
  2. We want to feel that our line is part of the modern railway network and not a neglected backwater. Although Network Rail has done some limited rerailing we still have a lot of jointed track with bullhead rail and wooden sleepers. The line is being overgrown with vegetation and the ballast is compacted with soil and other contaminents. Network Rail has no plans for further track renewals before 2024 (CP7), although it continues routine monitoring of track condition.
  3. Electric trains have better acceleration and are cheaper to run and to maintain.
  4. Environmental improvements - noise and emissions - benefit people living along the line.
  5. Electrification would release much needed diesel multiple units for use elsewhere on the network, in a cascade of rolling stock which will eventually eliminate the unloved Pacers.

So Why Don’t We Electrify?

For the electrification of the main line, GWR will get a number of new or nearly new electric trains (class 387). All these trains are 4-car electric multiple units (EMUs) which can form trains of up to 12 cars. The problem is that for a train to reach Marlow it must reverse at Bourne End, but there is only enough room between the buffer stops at Bourne End and the junction for the Marlow branch for a 2-car turbo.

There are no 2-car 25kV (overhead line) electric trains, but a 3-car train with 20m coaches would just fit so GWR would need to find some existing 3-car x 20m trains for the branch. A bespoke build for the branch would blow the business case for electrification out of the water.

What’s The Solution?

The Class 313 trains currently operating out of Moorgate will be replaced by new trains, but they are 40 years old so life expired and would in any case be a retrograde step in terms of passenger comfort.

The only other 3-car x 20m 25kV AC electric units are ScotRail classes 318, 320 and 334. These are being refurbished for ScotRail. ScotRail is converting some other 4-car units to three cars so would clearly not be interested in having 4-car units in exchange.

The new Class 387 Electrostars have 20m coaches but conversion to 3-car units would not necessarily be simple as various items of equipment are distributed along the train. It would obviously be necessary to retain the two driving motor coaches and the pantograph trailer so equipment located on the non-driving motor coach would need to be relocated (including the accessible toilet module).

There is one other possibility. Southern has a small fleet of trains designated Class 377/3. These are equipped for 750V DC third rail operation but are designed to be dual voltage and could be converted to 25kV AC overhead line. Moreover they are Bombardier Electrostars so have a lot in common with the new Class 387s and would not be difficult to maintain. Southern (now part of the Govia Thameslink Railway franchise) will be awash with EMUs because of all the new trains being introduced for Thameslink and Gatwick Express, so filling the gap would not be a problem.

Mark Hopwood (GWR MD) comments that Southern will need its Class 377s as it will soon have to retire its own Class 313 fleet which serves the Coastway route, and the Electrostar assembly line is now closed. However we note that Transport for London (TfL) would like to take over suburban routes south of the Thames and integrate them with the Overground network, so could introduce new high density walk-through trains on those lines.

The branch would require a dedicated mini-fleet of at least three units which are slightly different from the rest of the fleet. This would be no problem for Reading Traincare Depot which currently maintains two very non-standard prototype Class 150 Sprinters for the Reading - Basingstoke service. They will probably join the rest of GWR’s Class 150 fleet in the South-West.

Would We Be Any Better Off?

Make no mistake, the Networker Turbos we currently have are seriously good people movers. They have lots of reasonably comfortable seats in stark contrast to TfL’s obsession with inwards-facing seats, no toilets and standing room only for most passengers. Chris Green, then General Manager of Network SouthEast, got it just about right when he specified the Networker fleets in the 1980s. Our Turbos were introduced in 1991.

The better acceleration of electric trains would save one or two minutes per journey, but this is not enough to allow a jump in frequency. This is in contrast to the Henley branch where electrification will permit an all-day 30 minute interval service instead of 45 minutes as now (40 minutes is possible but doesn’t mesh with four trains per hour on the main line). GWR is currently planning a 30 minute interval service using Turbos but omitting alternate stops at Wargrave.

The LEP Scheme

Great Western Railway, in conjunction with the Buckinghamshire Thames Valley Local Enterprise Partnership, has been working on a scheme to upgrade the infrastructure at Bourne End so as to facilitate an all-day 30 minute service without having to change trains at Bourne End. This involves laying an extra track from the up platform (2) to the Marlow branch, with the necessary points and crossings. The layout would need to be fully signalled as there would be conflicting movements, although as a cost saving measure Network Rail is considering a local panel at Bourne End to control movements there. This would not be vastly dissimilar to the present crew-operated installation that works the points in conjunction with the single line token equipment.

The Marlow-Maidenhead Passengers’ Association strongly supports this scheme but we understand that there is still a funding gap that needs to be bridged. If it goes ahead it will be a major boost to the line and to the economy of the towns it serves.

Given the possibility of the Bourne End scheme going ahead it makes sense to hold off electrification. Once the masts are up it becomes much more complicated, and therefore more expensive, to make changes. Not only would the overhead line equipment (OLE) have to be modified, but it’s a lot easier to crane track panels into place if you haven’t got masts and overhead wires in the way! It would be possible to make passive provision for the layout changes but that would require the detailed design for both track changes and electrification to be done at the outset. GWR is not able to commit further resources to the project until it is fully funded.

Red Herrings

There are some popular misconceptions that need to be dealt with.

  1. Selective Door Opening (SDO): the problem is the overall length of the train. If the back end of the train doesn’t clear the points it doesn’t matter how many doors are kept shut. SDO doesn’t help.
  2. Through trains to London: this is a separate issue and is related to track capacity on the approaches to Paddington. After electrification of the main line the Marlow and Henley-on-Thames branches will operate shuttle services throughout the day. Whilst we regret the loss of through trains it does mean that the branch line service will be more reliable as a result.
  3. Crossrail: although Crossrail will provide the stopping service the franchise (currently GWR) is still expected to operate two trains per hour off-peak from Reading calling at Twyford, Maidenhead, Slough, Ealing Broadway and Paddington. We expect that the branch line trains will connect with these services. There will also be some fast trains to and from London in the peaks as at present.

So electrification is possible but not urgent. It would need to be addressed before the Networker Turbos reach end of life. Nevertheless we should press the Government and the DfT to include electrification to Marlow in the specifications for Control Period 6 (2019-24) and the next franchise, and keep it there.


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Last updated 17th November, 2016