Signal aspects - eror in email addressing

NW Modeling List nw-modeling-list at
Thu Jan 17 20:40:53 EST 2008

I believe the ³upper left ­ lower right² diagonal indication is used the
same way the lowest of the three arms was on semaphores. I heard signal
towermen refer to those bottom arms (which were also shorter than the two
arms above them) as ³calling arms². This arm could only be raised to a 45
degree angle, and could over-ride some of the interlocking components to
allow a train to enter the interlocking ³prepared to stop short of
obstruction² . Jim Mihalek referred to this indication as ³restricting² for
trains entering the yard. When I used to ride the Rock Island commuter
trains into Chicago from the Morgan Park branch, the Gresham Junction signal
would give a lunar white indication on the bottom of three heads to indicate
that the train would take the curved path through a double slip switch to
get on the express track. So, this ³restricting² indication apparently can
be used for any very slow speed operation past a home signal. Another
advantage of the position light signals was that this third and lowest
signal indication on three arm home signals could be combined with the one
above it by reversing the angle of the row of lights.

Bob Folsom
Clemson, SC

On 1/16/08 6:23 PM, "NW Modeling List" <nw-modeling-list at> wrote:



> Marty: sorry my finger slipped and put an extra 'l' in modeling. So I will

> retransmi my request and all should be well this time. Interestine that in

> spite of the error it must have reached you for you to be able to correct the

> error of my ways. Thanks very much for doing so. Here goes ...


> Signal aspects


> The recent exchanges on signal indication have been most interesting. In

> particular, there seemed to be uncertainty about the (rare) use of the top

> left to bottom right diagonal group on position light signals.


> In the picture on the cover of the 2002 calendar the signals shown have two

> heads on each mast, the upper ones having vertical, horizontal, and bottom

> left to top right diagonal positions. However, the two lower heads have

> vertical, and both diagonal options, and no horizontal group. What would be

> the information shown by the possible use of these lights?


> There are three tracks approaching the junction but only two signal masts,

> which are well to the right of all tracks. How do these signals relate to

> three tracks for approaching trains?


> Ted Roberts (UK)



> ________________________________________

> NW-Modeling-List at

> To change your subscription go to


> Browse the NW-Mailing-List archives at


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the NW-Modeling-List mailing list