signal questions 3 (NW Mailing List)

[NW Mailing List]

> John Garner asked:
>> >Is there a chance that rather than "an eastbound movement lined on the near
>> >track (main 1)"  that it could also be a westbound movement on the near
>> >track (main 1), running reverse main, that has just passed? Just a thought.
     If the the signal shown is a control point, then, yes it could be 
lined as you ask...after the crew has contacted the dispatcher and he 
lined the signal up. If this was an intermediate signal, then, it 
normally wouldn't automatically line up like that. The entire train 
would have to clear the section between this and the next westward 
control point before the current of traffic could be reversed.

     Let me give you this example about the "Current of Traffic". Let's 
take two control points, Elkton and Lewis Run. Between these two control 
points are four signal blocks. Running south from Elkton the next signal 
is an intermediate at MP 114.7. The next signal is at MP 117.5. The next 
at MP 119.3 and the next at MP 121.7. Now, let's suppose that a local is 
switching the Merck Stonewall Plant at MP 115 and is asked by the 
dispatcher to clear up for a southbound train. After the southbound 
train passes Elkton it sets up a southbound "Current of Traffic" between 
Elkton and Lewis Run. As soon as the train clears the switch at 
Stonewall, the local asks to open up and go back north toward Elkton. 
Permission is granted by the dispatcher, the crew opens up and starts 
their northward move at restricted speed to the next signal. The next 
signal is at MP 114.8 (same location as 114.7 but as it is the 
northbound signal it has an even number). This signal will display a 
restricting aspect because the southbound train hasn't cleared the 
signal at Lewis Run yet and the "Current of Traffic" is still set up in 
the southerly direction.
     If after the southbound train passes, the local crew is still 
switching inside the plant it may be some time before they need to open 
up to go back north. If in this time, the southbound train completely 
clears the signal at Lewis Run, when the local asks to open up and go 
north, the signal at 114.8 should be approach until the dispatcher lines 
the signal at Elkton up for northward movement, in which case the signal 
114.8 will show clear if it hasn't yet been passed by the local.

     Now, let's say that the local asked to open up and follow the train 
south. They would run restricted speed to the next signal which would be 
the one at MP 117.5. Depending on how many signals the train ahead has 
entirely passed, the signal at 117.5 could be clear, approach or 
restricting.

     Another thing about the "Current of Traffic". There were times when 
opposing trains would meet and after passing the dispatcher couldn't 
line the signals up because of a stuck relay. He would then talk the 
train by the control point and it would proceed at restricted speed, 
usually all the way to the next control point miles away. If you were 
riding in the cab, as you passed each opposing signal , it would line up 
and display the appropriate aspect in relation to where the signal was 
located. In other words, if you were heading south, the first northbound 
signal passed would line up and display an approach aspect, the next a 
signals would line up and display a clear.

Jimmy Lisle