What's the technical difference (if any) between normal tracks and tracks for high speed trains? Many Thanks

Question

What's the technical difference (if any) between normal tracks and tracks for high speed trains? Many Thanks

Answer 1

I have limited knowledge in the "high speed" area, but the differences I do know of are primarily in what lies beneath the rail.

For one, the cross ties are usually made of concrete, as opposed to the much more common wooden ties.  In addition, underneath the rail between the bottom of the rail and top of the tie, high speed roadbed incorporates rubber tie plates, which are nade of steel when using the conventional cross ties.  The rubber helps to dissipate high force levels.

In addition, the rail is bolted to the ties as opposed to being laid with spikes.  

As far as the rail itself, I will make an educated guess that it is lighter than that which is found under heavier freight trains.  In this instance, main line rail is usually the 139 lbs. variety.  This indicates that three feet of the rail would weigh 139 lbs.  All rail weights are stated by the weight per yard.

Curvature is usually super-elevated, or "banked", so the trains and the passengers within are subject to less Gs.  And, as pointed out above, the curves are much gentler in radius.

Answer 2

The line must be as straight as possible which means e.g. that many curves in the UK were eased to take trains running at 125mph. Even a slight curve means a speed restriction. Track must also be as free of gradients as possible. This was always the case with rail lines but for high speed running it is even more so.

Points must be as few as possible, facing points (those where the tracks diverge in the direction of travel) avoided wherever possible, and fitted with ultra-safe locking devices where their presence is unavoidable. It was the failure of one of these which caused the recent derailment in Cumbria, UK. Points must be of an advanced type where the frog (the part where the rails of converging / diverging tracks cross over) is switchable as well as the blades (US/Canada switchrails), the parts of the point which move to change direction of the track.

Signals must be set so far apart that a train running at max. permitted speed can come to a stop between a signal at 'caution' (i.e. indicating 'next signal at danger') and the danger signal. In the case of British HSTs designed for max. speed of 125mph, this is at least 1 mile. Signals are supplemented by repeaters or AWS - type indicators in the cab.

One problem with the catenary (support structure for overhead electric power lines) is that the constant passage of the regularly-spaced masts is thought to have a hypnotic effect on the driver and the window arrangement of the cab is designed to minimise this.

The wires and pantograph (device on the roof of train for picking up current) have to made of special heat-resistant material. In 1955 when a French electric locomotive set a then world speed record of 205mph, the pantograph was found to be glowing white-hot.

Answer 3

larger radius turns