Branch line interlocking

[NW Mailing List]

The following suggestions are based on N&W signaling practices after about
1950. Exceptions abound, but are avoided here—this stuff can get confusing
enough as is.

Add diverging aspects to the two controlled/interlocking/home signals
governing the diverging route. The diverging or secondary route is through
the switch in the open/reverse position, with (more) curvature, and often
at lower speed. So regarding the home signal on the branch route, replace
the aspects Clear and Approach with the diverging equivalents, Diverging
Clear and Diverging Approach.

Regarding the home signal to the right, it governs both routes, so it would
be able to display Clear and Approach or the equivalent diverging
aspect(s), depending on the position of the switch. As drawn, being able to
display only Diverging Approach would likely indicate that TC ends on the
diverging route at the next (and last) signal, which would be a
fixed-aspect of Restricting. Add Diverging Clear if TC as drawn on the
branch route, extends farther to two or more blocks (and signals).

Regarding the automatic distant signal on the main route to the left, omit
the lower arm for Approach Diverging. The following home signal cannot
display diverging aspects. Only controlled signals governing a diverging
route can display diverging aspects and when doing so are preceded by a
signal displaying Approach Diverging. Also, it would display Approach in
figure 2.

The distant signal on the branch route would display Approach in figure 1
and Approach Diverging in figure 2.

Omit the two automatic signals, one on each route opposite the home
signals, to look like the right end of the junction with the lone home
signal. The next signal outbound from an interlocking is not at the
interlocking limit opposite the inbound home signal, but a “long” block
away, allowing a movement to clear the interlocking before having to stop
on signal. 

The automatic signal outbound from the junction on the branch route in
figure 1 and on the main route to the left in figure 2 could display a
clear or approach depending on conditions ahead. A signal’s normal or idle
aspect is displayed in the absence of traffic or lined routes. Controlled
signals display Stop and Stay and automatics display Clear, except Stop and
Proceed on reverse main and Approach on distant signals. 

Hope this helps. I think you asked about Eckman—I’m trying to catch up.

Grant Carpenter


> Date: Wed, 16 Oct 2013

>

> Thanks for all the good feedback on my siding diagrams.  Now how about a

> junctions where a signaled branch joins the main (see diagrams below)?

>

> [image: Inline image 1]

>

>

> [image: Inline image 2]

>

> Once again all comments/corrections gratefully appreciated.

> Jim Cochran

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