Readers letters
Steve Beck (“Hybrid Rail Systems Needed”, PE May) says the use of diesel traction on long sections of electrified routes is one of the most wasteful and unnecessary uses of fossil fuels in existence. Not only that, the use of diesels defeats the whole point of electrification. And whilst converting trains with underfloor diesel engines and electric transmission to hybrids is eminently suitable for some services using electrified routes, hybrids are not the universal answer to diesels under the wires.
The Voyagers working the Cross Country routes from Edinburgh, Newcastle and Manchester through Birmingham to Reading, Bournemouth, Bristol and Plymouth all have approximately 40% of their mileage under the wires. Converting these trains to hybrids would make excellent technical and economic sense. They would operate as electric trains between Manchester and Longbridge/Coventry and also north of Doncaster/York, with the diesel engines providing power for the remainder of the journey. Further electrification planned for the trans pennine route, the midland main line and in the Birmingham area would increase the amount of electric working.
However the Voyagers on the Birmingham to Glasgow/Edinburgh service spend 100% of the journey under the wires and converting these trains to hybrids is pointless. This route would be better served by the use of Pendolinos and extending some of the London to Birmingham diagrams to Scotland. Also the London to Chester service is approximately 90% under the wires and the answer here must surely be to electrify the 20 or so miles from Crewe to Chester and again use electric trains. For this service Alstom has proposed a shortened Pendolino with rapid couplers to be diesel hauled to Holyhead where called for in the timetable.
The HSTs on the London to Aberdeen/Inverness service travel 393 miles under the wires in order to continue north of Edinburgh. Electrifying the 130 miles or so to Aberdeen is difficult to justify for only four trains a day and to Inverness is totally out of the question. But diesels under the wires all the way from London to Edinburgh is madness and the answer must surely be to replace them with electric trains and diesel haul them north of the Scottish capitol. The schedules have 10 minutes standing time at Edinburgh for passenger/recovery purposes so attaching/detaching a diesel ought not to cause delay. And if the Scottish Parliament decides to electrify the line in the future for Scotrail services then the diesels could be dispensed with.
The Meridians on the London to East Midlands services spend only fifty miles of a relatively short journey under the wires and the case for conversion to hybrids is marginal. But this route is also earmarked for electrification so converting these trains to hybrids is probably pointless.
Electric trains have been ordered for the Manchester to Glasgow/Edinburgh service, currently worked by diesels but 100% under the wires when electrification in Lancashire is completed in 2014. All other long distance services worked by diesels (e.g., Manchester to Cardiff) travel only short distances on the electrified network and in any case have torque convertor type transmission which cannot be converted to hybrid.
So what are the conclusions. Firstly electrified railways really should have electric traction as much as possible, obvious you may think but certainly not the case at the moment. On the west coast north of Weaver Junction there is currently only one electric passenger train per hour all the way to Glasgow, all the rest are diesels and most of the freights are diesel too. Secondly hybrids are only really suitable on long routes with roughly equal proportions of electrified and non-electrified railway. There is no point in hauling dead diesels and fuel tanks around all day just to serve short sections beyond the wires. Finally new electrification schemes should include infill areas (secondary routes, freight yards, etc) in order to permit the maximum use of electric traction. There is no point in half doing the job.
Paul Thomson, Weaverham, Cheshire
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