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Speed limits


Railtrack's inherited obligation to run freight on Section One of Britain's first really high speed railway could well be described by that management euphemism; 'a challenge'.

Conventional freight trains are banned on all other high speed railways in the world, for very good reasons.

They drastically reduce line capacity for fast trains, lower the geometric quality, and they wear out the track.

The obligation to run mixed traffic on CTRL dates back to 21 May 1993 and a Department of Transport 'Design Standards Brief' which set out that the route should be built to international loading gauge standards and 'carry freight in addition to passenger traffic'.

That requirement was reinforced by further documents, including a Select Committee Interim Report of 20 July 1995. It said that the freight loops (bypass sidings four-tracking the line at Lenham and Singlewell) must be provided to ensure that CTRL 'should be capable of carrying as much freight as possible'.

Railtrack's man on the spot Chris Jago, managing director of Union Railways (South), interprets the obligation like this: 'Our position is that we are only too pleased to run freight.

'But we can see it as a problem if it runs at 140km/h. This is a hilly and curvy railway with gradients of 1 in 40, ' he says. 'At times on the steep gradients the speed will be down to 70km/h and where there are curves this will make it uneconomic due to the wear and tear on the rails.'

Rail lines are set to a cant on curves.

Cant is calculated to formula and applied to allow for trains occasionally running slightly slower than maximum design speed for the bend. But Jago warns that for curves designed for 300km/h carrying freight traffic at 70km/h: 'wear and tear is horrific'.

The cant excess would cause the wheels to grind against the inner rail.

Freight traffic with an axle load of 23t compared with 17.5t for passenger trains would make damage particularly severe.

'When I came in (to URS in January 1999) we were going to run at 270km/h.

If you have freight running at 70km/h and passenger trains running at four times that speed it is not a robust way to run railway.'

Jago decided that the operating capacity of the line necessitated a maximum design period of 300km/h for Eurostar trains in order to allow the minimum St Pancras to Channel Tunnel timing to be reduced to 31 minutes.

Running freight trains late at night, rather than during offpeak hours during the day when they would still have to dodge in and out of the passing loops to avoid Eurostars, may not be an option.

High speed railways require a great deal of regular maintenance to fettle the track alignment. Jago favours Japan National Railways routine of regular night time closures of one track at a time to permit work.

His answer?

'We are looking at a new type of freight. If we could develop high speed freight trains it would solve a problem on the East and West Coast Main Lines.

'We can see a real opportunity, ' enthuses Jago. His concept is 200km/h trains carrying high value, relatively lightweight freight. Undercarriages of the trains would be developed from passenger vehicles.

The bodies would have gull-wing or other wide opening side doors that would allow the rapid loading and unloading of palletised goods. Jago sees the market as being in through- trainloads of freight such as motor vehicle panels, linking factories throughout Europe.

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