Steam & Preservation

Several pictures in the Locomotive Cyclodepia refer to a "train control box" mounted on steam locomotives.  What is "train control" and how did it function?  Was this technology successful?

Thanks,

Martin

 The box houses the electrical apparatus for either an Automatic Train Control system (ATC) or an Automatic Train Stop (ATS) system.  Both are types of wayside signaling systems that seek to prevent trains from exceeding their authority, exceeding a speed limit designated by a wayside signal, or exceeding a permanent speed limit.

In broad terms, the train control equipment works as follows.  It obtains an electrical signal from the rail or from trackside inductors.  Typically the frequency of the signal contains train-control maximum speed information.  The train-control box compares the information to what the train is actually doing.  For example, if the signal says "travel at no faster than 35 mph" and the train is traveling at 40 mph, the train will be automatically braked. 

As to successful, yes, ATS and ATC were made to work, still work, and are still being installed new, in the U.S. as well as many other countries.  They are costly and imperfect, however.  "Success" is a relative term.

RWM

Not that I am especially sought for my prowess in things railroading (cough...), but as RWM states, it has been around a long time, and for any rational business model to have extended its use past, say, a decade, suggests to me that it is indeed successful.  It must save some unwanted costs that would otherwise damage the corporate integrity some way.  That could just mean bad publicity, or it could mean increased dividends to shareholders, and a host of things in between.

RWM, or anyone reading who knows, when we say the train is 'braked', are we talking braked in a penalty way...to a stop...or merely reduced to local track speed?  What are the implications in either case, both for schedule/traffic and on the crew?  I am unclear on this aspect.

-Crandell

Crandell -- ATC and ATS come in many different flavors.  There is almost every possible permutation in how they work.  It's very location-specific and time-specific.  The effect is the same but the process -- very different!

The technology has been around since the early 1900s.  Its desirability was not broadly accepted by the railroad industry because the industry except in certain applications did not find it to be cost-effective.  The ICC mandated ATC on a test district (a complete subdivision) on 49 railroads in June 1922, with an additional 47 railroads so directed in January 1924.  These railroads were selected on the basis of traffic density and speed, thus low-density or low-speed Class 1s were excepted.  Some railroads installed automatic cab signals in lieu of ATC. 

RWM

Railway Man:

The technology has been around since the early 1900s.  Its desirability was not broadly accepted by the railroad industry because the industry except in certain applications did not find it to be cost-effective.  The ICC mandated ATC on a test district (a complete subdivision) on 49 railroads in June 1922, with an additional 47 railroads so directed in January 1924.  These railroads were selected on the basis of traffic density and speed, thus low-density or low-speed Class 1s were excepted.  Some railroads installed automatic cab signals in lieu of ATC. 

This first directive applied to all railroads with more than $25 million annual revenue.

The ICC sent out an additional directive, in 1947, which was applied to all railroads.

This directive specified that a manual block or automatic block system must be in effect for a freight train to be operated at 50-59 mph, and/or a passenger train was to be operated at 60-79 mph; if either of these speeds was to be exceeded (59 for freights and 79 for passengers), the railroad had the choice to operate with ATS, ATC, or cab signals--or reduce the speed of its trains. The railroads were given to the end of 1952 to complete the installation. Not all railroads were willing, or able, to comply with the directive and, as a result, lengthened the schedule of all trains that required the higher speed to maintain their schedules.

See Trains, August 1947, pp. 4-6.

Johnny

Isn't metroRail in LAX installing ATS on all lines they own due to what happened in Chattsworth?

Thanks, RWM.

-Crandell