The Engineer's Notebook Blog

The Engineer's Notebook

The Engineer's Notebook is a shared blog for entries that don't fit into a specific CR4 blog. Topics may range from grammar to physics and could be research or or an individual's thoughts - like you'd jot down in a well-used notebook.

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Load Gauges and Railway Construction (Part 2)

Posted January 05, 2010 12:01 AM by PWSlack

While I.K. Brunel was making extraordinarily wide railways towards the west of the U.K. in the nineteenth century, other Engineers were struggling with the balance between first cost and opening date elsewhere, resulting in some interesting compromises. Making things a bit smaller made them a bit cheaper, and if money and time were tight then so it had to be. The line to Hastings was a particularly awkward one, a small tunnel requiring the design of especially narrow rolling stock for that route. Upon recent electrification the line through the tunnel was singled, and the need for the narrow stock disappeared.

Gauging Trials and Engineering Errors

The practice in the U.K. is still to carry out "gauging trials" on lines before new or unusual rolling stock is used. Three recent incidents come immediately to mind with varying degrees of humour and alarm to accompany them:

  • The sole surviving class 306 3-car overhead-electric unit was towed over the 3rd & 4th rail electric Metropolitan Line of the London Transport network a few years ago. Metropolitan Line trains are in themselves a bit wider than most regular U.K. stock and the 306 is similar. Imagine the consternation caused at Rickmansworth station, which is sharply curved, when the said 306 cleared the platform canopy valance by only a couple of millimeters.
  • Some brand-new Chiltern Line trains had to be restricted from certain routes owing to the outward-opening plug doors fouling the platforms when opening during initial testing and thereby becoming mechanically inoperable.
  • And a tall heritage steam locomotive, in steam, caused major panic and emergency action by the crew when its safety valves struck an overbridge on a line where proper gauging trials had not been carried out beforehand, breaking these fittings clean off the top of the boiler…

The TGV in Kent: Mission Impossible

The film "Mission Impossible", starring the US actor Tom Cruise, is excellent cliff-hanger entertainment. It is rather spoilt as far as the purist is concerned by the inappropriate depiction of a French TGV train streaking through what is supposed to be the Kent countryside towards the Channel Tunnel rail route. The TGV, amazing as it is and being the same track gauge, is simply too tall and too wide to operate over Kent's lines, which is why the superb Eurostar trains, shorter and thinner to suit the UK's smaller loading gauge, operate all the way from London to Paris and Brussels over the TGV routes instead while they pass through France. Indeed, when the time is right, they could probably take him over the new high speed network all the way to Madrid.

From Mallard to Bullet

The UK's National railway Museum is located in the city of York, and it has a deserved international reputation. At the time of writing, admission is free-of-charge. Under an arrangement with Japanese Railways, it took delivery of one of the driving-end vehicles from a retired "bullet train". Both of them being painted blue, it stands gloriously and impressively alongside "Mallard" (image at right), still the fastest steam locomotive in the world, at the entrance to the main gallery. Although both are to the same track gauge, what isn't generally known is that the bullet train vehicle is so wide that, as it was being gently propelled into the building, it only cleared the main entrance doorway by about the thickness of a coat of paint.

Editor's Note: CR4 would like to thank PWSlack for contributing this two-part series. (Cheers!) Click here if you missed Part 1.



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Re: Load Gauges and Railway Construction (Part 2)

01/05/2010 10:27 AM

Thanks for this excellent summary. Just a couple of points to supplement what you wrote:

1) Due to the problems of the multiplicity of gauges, Indian Railways has Project Unigauge in progress to convert much of the meter gauge to broad gauge (5'6") and several lines have already been converted.

2) The Hastings line was not deliberately built to tight clearances. Cowboy builders built the offending tunnel small to save money then lined the offending tunnel with only one layer of brick instead of the four layers specified so it appeared to the normal size. When this was discovered the tunnel had to be reinforced with another 3 layers inside the existing layer thus leaving it too narrow to take normal stock.



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Re: Load Gauges and Railway Construction (Part 2)

01/05/2010 1:37 PM

Good stuff, well collated. Just a point that the TGV lines are built straight in plan, where the older (steam) british rail lines had to be fairly level but speeds of a hundred miles an hour were not envisaged at the time of building. By 1880 trains were running at a hundred quite often. Engineering, maintenance and signalling were not up to it, though the days of the permanent way man aught to come back, with the responsibility. Too many layers nowadays. I saw recently a mag letter suggesting that the new high speed london>north line should be accomplished by straightening the loops that were originally ran down to the ports. The cost of new track is a tenth, the time scale also much reduced. A NEW line is not required to achieve most of the objectives. The proposals were for the east coast line and are proven by the new UK only services available on the Chunnel line. Try Siam for train simulators. Numerical only but a real challenge to get a run from a steamer, from 2-6-2's onwards. Mallard included.

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Re: Load Gauges and Railway Construction (Part 2)

01/05/2010 3:27 PM

More please!!

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Re: Load Gauges and Railway Construction (Part 2)

01/06/2010 10:49 AM

Very interesting blog. We have to ignore past railway gauge practices when we enter into the world of high speed rail. If we are to have speeds in excess of 200mph, more design will need to be done in support of the higher speeds. High speed rail must depend on straight stretches of track, so old rail lines of no-matter what gauge used, can never be utilized for high speed running.

Not to sidetrack your blog; it's my opinion that high speed rail in the future must and will be via monorail and for passenger use only. Monorails will be cheaper to construct as they don't require a great deal of real estate for right-of-way. There are no highway crossings to consider and they can be run along public roadways in conjunction with DOT (department of transportation) roads. Freight will always be handled by conventional rail lines at lower speeds.

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