How is a fault in railway system detected?& How is it corrected?

Question

About THE FLAWS IN RAIL TRACKS

Answer 1

There are speciality service companies out there such as Sperry Rail that have trucks mounted on little railroad wheels that cruise down the tracks every now and then (depending on train volume).  They have sensors that test the rail for hidden hairline tracks and other defects.  Railroads also have employees called rail inspectors that regularly (sometimes daily) drive the tracks in pickup trucks with little wheels on them, looking for obvious problems visible to the naked eye.  They actually do find things from time to time.  

Most defects are small and are fixed by the railroad.  They have a whole operating unit called Maintainance of Way.  These are the road crew.  If the track is damaged they will often cut that piece out and weld in a new section.  If the flaw isn't judged to be immediately dangerous the Roadmaster (boss of the road crew) will put up a yellow square called a "yellow board" that tells the engineer to go very slowly over that section.  The railroad stops the trains while the track is being worked on, of course.  If the job of repair is really big or specialized, sometimes smaller railroads will contract an outside company to come and do the repairs.  Some of the other companies involved in fixing tracks/maintainance are Loram and Hulcher.  Each specializes in their task.

Kent in SD

Answer 2

Track is inspected either by eyeball from inspection cars, or with special track analysis cars packed with electronic instruments.

Track foremen and division engineers used motorcars

http://en.wikipedia.org/wiki/Speeder

http://www.narcoa.org/

and now hy-rail trucks

http://en.wikipedia.org/wiki/Hy-rail

http://www.fairmonttamper.com/hy-rail.ht...

to get down the track so they can eyeball the state of the railroad.  This lets them see visible defects like bad ties, washouts, sun kinks, broken rails and the like.

For detailed analysis of track geometry and the condition of the steel rails, special track analysis cars are used.  They use mechanical devices or lasers to check track geometry (gage, cross level, chord etc.) and ultrasound, electromagnetism or other methods to detect flaws inside rails which might lead to rail breakage.  In the rail industry, Sperry (later Sperry Rand Co.) is practically synonymous with this service.

The August 2007 Trains magazine has an article about railroad business cars, many of which are now also track inspection cars, equipped with a large picture window and theater seats to inspect track visually, and equipment to inspect the track mechanically.

Answer 3

Here in Spain special trains (even high speed) control daily a part of the tracks, running the line, and all the electronic equipment controls both the tracks and the overhead lines for the electric supply.

Answer 4

Good question.

In a signaled system there are tiny currents throughout the rails, if one of these currents is interrupted it throws the signals red, signifying a break in one of the rails. After diagnostics to narrow the possible area of the interruption, a signal maintainer usually inspects the rail visually.

Periodically, RRs run "rail detectors" over the tracks, they sense flaws that are internal, mostly magnetically although I know there is another way, perhpas sonically.

This would be the only way to detect flaws in "dark" or unsignaled territory where there is not circuitry to sense flaws built into the system.

And there is always the old fashioned way of employees spotting breaks as they are on or about the tracks.

The last way is the way we try to avoid, by having something break under the train and causing a deraliment.

It happens despite the best efforts to prevent it.