How are the turnouts on real railroads controlled? I know at least some of them are controlled manually because I've seen someone hop off a train to manually operate the turnout. If some turnouts are remotely controlled, how are they triggered and who triggers them?

The Metrolink train that crashed in L.A. apparently came off a siding and passed through the 'out' position of a turnout where there was a red light. The turnout should have been in the 'thru' position for the U.P. train. I assume that the switch must have been in the 'out' position or the Metrolink train would have derailed. So who or what determined the position of that turnout?

I hope I got the terminology correct.

Thank You...
Earl

There is so much crap written about that wreck that it is impossible to know excatly what did occur. But it is my understanding that the commuter train was on the main line and the freight was to go through the siding. The track switches were lined into and out of each end of the siding for the freight to pass through the siding. The commuter train ran through the north switch, breaking it.

Remote control track switches are "Dual Control" switches in western RR terminology. They are normally "thrown" (called "lined" by railroaders) to one position or the other by the dispatcher who can be 2000 miles away. At large Manual Interlockings or some yards the switches may be under the control of a tower operator or yardmaster who remotely lines the switches, usually under the jurisdiction of the train dispatcher.

A switch is said to be "lined normal" when it is in the main line position and is said to be "lined reverse" when in the diverging position.

The electrical commands to operate the switches come from the dispatcher's office and are carried to the remote site via the RR's own control wires, commercial telephone wires, RR microwave, radio, or even the cell phone system depending upon the system in place and its age.

At locations called "Automatic Interlockings" Dual Control switches can also be operated by approaching trains. Track circuits detect the train's approach and cause the track switches to align for that train's path. This is much like the "non-derailing" feature of 3-rail model RR switches except that it occurs when the train is much farther from the switch. (A real train will not derail if it trails through a switch lined for the other direction. It simply breaks the switch).

Some dual control switches are semi-automatic. At these locations if a train is directed by track warrant to enter a siding the train is stopped and a crew member gets off and pushes a button to cause the switch to align for the siding. After the train pulls into the siding and clears the switch it will automatically re-align itself for the main line. On some RR's these types of switches can be remotely thrown by the crew using the touchtones on the radio, that way the train does not have to stop.

Remote controlled switches are called "Dual Control" switches because they can be operated remotely as described above or they can be operated mechanically by hand by a crew member at the switch. It is very much like the remote control switches on a 3-rail model train layout where you can line the switch remotely or by hand.

The switch in question at the Chatsworth wreck this weekend was controlled by the Metrolink dispatcher at the dispatching office.

Wyhog

This message has been edited. Last edited by: Wyhog,

quote:

Originally posted by Wyhog:
A real train will not derail if it trails through a switch lined for the other direction. It simply breaks the switch).

Wyhog

Now I learned something new. I always assumed that any switch would operate like a spring switch so if a train trailed through a switch set against it, the points would move over then return. Obviously not. Must be a twechnical reason why this is not done. I do know that you cannot do a reverse move through a spring switch once its has sprung so maybe this is the reason.

Thanks Wyhog, Always learn something new.
Sam

Wyhog, thank you for your detailed reply.

Does the turnout physically break? If so, what breaks. It seems incredible that a turnout could move with so much weight on it.

Earl

quote:

I do know that you cannot do a reverse move through a spring switch once its has sprung so maybe this is the reason.

Yes, that one's caught a few experienced railroaders by surprise. A train stalls 1/2 way out of a siding and decides to back in or the slack runs back. Ooops on the ground.. Actually you can make a reverse movement if someone sets the spring switch(SS) by hand for the route.

Most of the sidings in signaled territory(CTC) had a spring switch at one end when I started. Fun in the winter, the guys in the caboose had to make sure the switch points closed after leaving a siding. If the points didn't close the block would show occupied for the next train.Most crews were pretty good about checking the switch, leave too many open and you'd get a rep and the dispatcher wouldn't take a chance on you and let you sit in the hole until traffic cleared.