Great Western Coffee Shop

A Freight train set off the HABD just north of Oxford tonight and brought chaos to services on the Cotswold line. Some Hereford services diverted via Swindon and Cheltenham.

Glad I worked from home today!

Sorry - I have to ask - what is a HABD?

Hot axle box detector.

And one of them does what exactly?

It detects Hot Axle Boxes, silly.

And before you ask:

The offending freight train on 05/11/2007 was dragged back to Oxford at slow speed from Wolverton Junction and arrived at Oxford just before 2100hrs.

And I have to ask........

What is so offensive about a hot axle that it causes such chaos!

(I'm a mere passenger so forgive me if this should be obvious!)

The same thing that would happen to your car if the engine oil dried up, seizure of moving parts, the axle could seize up, could shear off, cause a derailment and if an HST travelling at full charge ran into the wreckage I will leave you to imagine the consequences.

Thus the reason that HABD's are stategically placed about the network to detect such occurences.

When one is set off the signals far enough forward are set to danger to enable the driver to bring the train to a controlled stop (rather than an emergency stop). On contacting the signalman the signalman can inform the driver which axle has set off the detector and whether it was the RHS or LHS axlebox. If confirmed a carriage and wagon examiner has to be called out to examine the item of rolling stock. It is on this persons shoulders as to how the train has to be cleared from the line. It may be possible to move the train forward at slow speed to a loop or set back to similar. In cases of an extreme hot box a wheel skate has to be brought to the site and the vehicle skated whilst the train is cleared from the line.

Whats a wheel skate I hear you say.

This is a device which can be described as a cradle with 4-inch flanged wheels onto which the offending axle box would be lowered after the item of rolling stock had been jacked up and the skate placed under the offending axle. The train can then be removed at slow speed to a point where it can be recessed for normal running to be resumed.

During the time that a hot box is being dealt with it is normal practice that no trains pass on an adjoining line in case the vibrations cause the hot box / axle to collapse and the carriage or wagon to lurch to one side and foul the adjoining track. Traffic therefore remains at a stand until the C & W examiner has carried out his inspection unless a diversionary route can be set up. After he has carried out his examination he may authorise movements on an adjoining line at a reduced speed but whilst operations such as the jacking the rolling stock up to place the wheel skate underneath traffic on an adjoining track has to cease. If a train is being moved forward to clear the line there may be instances where it encounters a train stopped on the line going in the opposite direction. At this point the disabled train has to stop and the other train moved forward at slow speed to clear. The disabled train can then normally only commence movement again on authorisation from the signalman as there may well be more trains to proceed past the disabled train from farther along the line.

In last nights incident it would appear that a light engine was sent forward to clear the freight train and the train was moved forward and then dragged back to Oxford using the crossover at Wolvercote Junction by the light engine sent earlier.

You might think its chaotic but its all in the matter of safety for both the passenger and the rail workers.

I agree

But I am an inquisitive scientist.

I can handle chaos if it is explaied as you did,

I cn extrapolate the consequences.

Someone saying a HAbD was set of gets me saying "WHAT".

mookiemoo.

Glad to have been able to enlighten you.

My next subject will be explaining what a TC failure is and why that causes chaos but that's not until you've genuinely encountered delays as a result of one.

Have a good day.