Thursday, April 20, 2017


A persistent problem observed during operating sessions has been firm knowledge of the Crescent Lake throat switch.  Crescent Lake is the upper staging yard, arranged as a reversing loop with twelve tracks.  The throat switch is high off the floor—over seven feet up--so crews cannot directly observe this switch without a ladder. 

The switch direction has been indicated by the toggle switch handle direction on the Crescent Lake panel.  Not all crews check this to confirm their routing. This has been particularly true for RR-East trains headed out of Crescent Lake and down the grade to Oakridge and Eugene.  Occasionally, the reverse direction (RR-West into the loop) has been an issue as well. 

I long planned to provide switch indication for this switch.  Re-railing yet another train over this switch during the April operating session finally elevated this project to a top priority. 

Switch direction indication was fairly easily accomplished with light emitting diodes (LED) working off contacts on the Tortoise switch machine.  Back-to-back (opposite polarity) diodes of appropriate colors provided the indication.  This switch does not have a “normal” or “reverse” direction of most switches.  Both routes through the switch have equal “value.”  The green and red indications ordinarily used for switches were not appropriate for this installation.  Instead, I selected amber and blue to indicate RR-West and RR-East, respectively.  These are the color of the Post-It notes we use for train information given to the Dispatcher.

A 1.1 kohm resistor was added to the back-to-back LEDs to provide current protection.  This simple circuit was then hooked up across the Tortoise drive contacts (contacts 1 and 8). 

I installed switch direction indication LEDs in the Crescent Lake panel along the layout fascia at the Crescent Lake throat switch location, and at the RR-West end of Cascade Summit. 

Crescent Lake panel with throat switch thrown for RR-West (in-bound) direction.

Crescent Lake throat switch thrown to RR-East (out-bound) direction.

Crescent Lake Throat Switch set for RR-East movement.  This is the view from the floor.  The throat switch points are under the clock.

Indicator panel for Crescent Lake throat switch (RR-West indicated) at the RR-West end of Cascade Summit.

I will find out if these switch position indicators help over the next month.

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