Train dispatching VS. Air traffic control

[DRBusse]

QUOTE: Originally posted by rich747us

Additionally, when a train is about to leave one dispatcher's territory and enter anothers, how do they know when to change radio channels? Do they just automatically switch at a predetermined point, or does the dispatcher call the train to tell them to switch channels and contact the next dispatcher? (kind of like how we did it in air traffic control)

Road channels are assigned between predefined points, and are published in the employee timetables. Sometimes these "channel change" points correspond with crew change points. Othertimes, they are waypoints along the railroad where road channels are changed "on the fly." In Southern California (Metrolink and BNSF territory) there are signs along the right-of-way at the exact points where train crews are required to switch radio channels. On passenger trains, engineer will confirm on radio to conductor that radio should be switched to channel so-and-so.

ATC's will assign exact frequencies to aircraft as they are handed off you'll say something like "Cactus 262 contact coast approach at 128.375..."

Railroaders will say "change to channel 36..." referring to the AAR scheme of railroad channel assignments. Or some railroads would say "channel 3636" to indicate that send and receive are simplex (same channel for both sides).

Another interesting difference between train dispatching and ATC is performance of the vehicles being dispatched. An ATC knows the difference between a King Air and a 747-400 and can assign flight levels and speeds accordingly. On the railroad side, a train dispatcher controls trains whose performance is determined by amount of power, length and weight of train along with the physical characteristics of the railroad. One day a certain train might take 45 minutes to make it from point "a" to a meet at point "b". Next day the same train, with the same power but different car count may very well take twice that long to travel the same distance.

Imagine you are in the tower and there are a half-dozen C-130s on the ramp, all with different wingspans, engines, rates of climb and takeoff weights. Same planes in name only. And imagine you must take all that into consideration when you assign flight levels and vectors after takeoff. That's something that a train dispatcher faces each day on a busy freight railroad.

Another big difference between ATC and train dispatching is occupancy of the fixed-right-of-way by maintenance crews...perhaps the most profound part of the "juggling act" that a train dispatcher performs. You flyboys just route traffic around things like storm cells, active volcanos, etc. The train dispatcher has to assign track and time to all kinds of forces that need access to the tracks...and run trains around them, or choreograph limited work times for the track gangs and others.

Finally, another advantage of ATC is the universality of the terminology. One day I was in the right seat of a helicopter asking for permission to enter the "class bravo" airspace at Long Beach, Calif. Three days later I'm in the jumpseat of an Airbus listening to the captain ask for permssion to pass over Larnaca, Cypress. Same language, same terminology, 6000 miles apart.

Sit in the dispatcher's office in a major western railroad and then visit the same for, say, CSX, and you'll hear subtle differences. Go to Canada and you'll hear lots of differences, including the name of the job itself (dispatcher in Canada is "RTC"--rail traffic controller).

Interesting discussion here...I'm sure more folks with greater knowledge than my spectator's point of view have more to add..

[BaltACD]

Crews arriving at terminals for trains are instructed by terminal personnel what actions they must take to get their train. Is the power on the train, is the power ready at the locomotive shop and must be taken to the train and attached, is it necessary for the power to be assembled from locations around the yard to be attached to the train. Once the crew has communicated with the Yardmaster or other terminal personnel and has the power attached to the train, the crew, at an originating terminal may have to 'double' one or more tracks together to make the final outbound train. To get permission to double the tracks together the crew must get permission of the Yardmaster or other designated terminal personnel, depending on terminal configuration and train size the crew may have to get permission of the Train Dispatcher to occupy the Main Track. While the crews are in Terminal Limits and not on the Main track they are under the jurisdiction of the Terminal Personnel (Yardmaster etc.) Train Dispatchers control all movements on the Main Tracks. Train Dispatchers and Terminal leadership communicate to allow for the safe and efficiment movement of trains throuh terminal areas on all tracks.

Once a train is ready to depart a terminal and either enter a Main track or move forward on a Main track after completing the trains air test will communicate with the Train Dispatcher to announce their readiness. In CTC Signaled territory the train will be instructed to follow Signal Indication. In ABS Signaled territory the train will obtain Track Warrent or Direct Train Control block authority for movement from the Train Dispatcher and then follow signal indication through the territory(s) they have received Warrent or DTC authority to occupy. In unsignaled territory the crew will receive Track Warrent or DTC block authority for movement and will operate solely on that authority. With DTC or Track Warrent authority, the crews may communicate and release territory or blocks behind the trains movement, the crew must obtain additional Warrent or DTC authority from the Train Dispatcher for territory ahead of the trains movement. The Warrent and/or DTC authority will specify meeting points with other opposing trains as necessary. In CTC territory trains operate on signal indication alone, when the trains come to Stop signals they will communicate with the Train Dispatcher for the reason for the Stop signal and possibly for authority to pass the Stop Signal.

Train Dispatcher with adjoining territories will communicate as to how and when trains will move from one dispatchers territory to the next. Timetable special instructions specify which radio channels trains must monitor form point to point as they traverse their trains route from subdivision to subdivision.

Upon arriving at terminating terminals the Train Dispatcher will communicate with Terminal managment on how and when to let the trains enter the yard,

The major difference between Air Traffic Control and Train Dispatching is that in the railroad the physical plant is fixed....tracks and sidings cannot be changed for the hour to hour ebb and flow of business. ATC has the availablity of the Third Dimension of Height to assist in handling increased volumes of traffic, once flights get on the ground, ground control responsiblities resemble those of a Train Dispather.

Good Luck!

[rich747us]

During my enlistment in the Air Force, one of the jobs I've had the opportunity to do was air traffic control. As a railfan I've been curious of the similarities and differences between ATC and controling train traffic. For instance, in aviation, prior to an aircraft's departure, the pilot will radio the 'clearance delivery' controler to recieve an ATC clearance. This clearance basicaly tells him which airways his approved route will consist of. Receipt of the clearance allows the pilot to take the next step which would be to conatct the ground controler and get taxi instructions to the active runway and of course, eventually calling the tower for a takeoff clearance. In the case of a train, are crews required to contact the yardmaster or dispatcher for clearance to depart, or do they just leave as soon as they have the train ready (air brake test complete, ETD in place, etc.) and see a proceed signal? Additionally, when a train is about to leave one dispatcher's territory and enter anothers, how do they know when to change radio channels? Do they just automatically switch at a predetermined point, or does the dispatcher call the train to tell them to switch channels and contact the next dispatcher? (kind of like how we did it in air traffic control) Would the dispatcher whose territory the train is leaving have to coordinate with the recieving dispatcher prior to the train entering the other dispatchers territory, or is there not much coordinating between the dispatchers of different territories? Thanks for any input!