2005 Classic calendar - Glasgow, VA - Frank Scheer's Qsn

nw-mailing-list at nwhs.org nw-mailing-list at nwhs.org
Mon Dec 13 21:08:29 EST 2004

Dr. Frank Shear asks:

The upper signal is the
three-aspect train order signal.  The lower signal is
the block signal, which is shown in normal position as
stop.  It was only cleared when the dispatcher
authorized a train into a block and the operator at
the next station beyond had its block signal as stop. 

The Train Dispatcher set up the train orders and took the OS's.  The 
operators "worked block" for trains between their adjoining block stations.  The 
dispatcher had enough responsibilities without getting involved in the blocking of 

On most railroads, the only case where the Train Dispatcher would be involved 
in "blocking trains" was that he was required to give approval for the 
issuance of "Permissive Cards" (i.e. a Clearance Card permitting a train to move on 
"permissive block" indication.)  

Generally "Permissive Block" is given for a second train to enter a block and 
follow a train moving in the same direction.  But it can also be given to 
opposing trains which are to meet by schedule or train order at a "blind siding" 
somewhere between two adjacent block stations.

As I recall, the N&W required the Train Dispatcher to approve Permissive 

In the old days, each station had one semaphore signal in each direction, and 
it was referred to as the "station signal."  It was used for a number of 
things simultaneously:  (1) to hold trains, (2) to space trains ten minutes apart, 
(3) to indicate whether or not train orders were to be received and the 
condition of the manual block (if any.)

In the very old days, there was no such thing as "block."  Trains simply 
proceeded on their rights under the timetable or train orders, and observed Rule 
99 for rear end protection !  I've always wondered when the N&W implemented the 
manual blocking of trains system wide, but have never found the answer.  I'd 
guess it was in the 1880s.

Now, let's whet your appetite on the top arm (train order signal).  Why would 
it be capable of displaying three aspects?  Any guesses...?

-- abram burnett
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://six.pairlist.net/mailman/private/nw-mailing-list/attachments/20041213/e15fb971/attachment.html

More information about the NW-Mailing-List mailing list