Main Line Signaling Project

The Middle Division main line will feature signaling driven by the Java Model Railroad Interface (JMRI). Engineers will operate their trains based on signals; no communication with the towers will be required.

The computer running JMRI is already in place and connected to the model railroad.

Detection utilizes Digitrax BDL168 detection boards. These are left over from my last model railroad. Each board supports 16 detection sections. Changes in occupancy are reported via LocoNet. JMRI monitors LocoNet.

Switch control utlizes NCE SwitchIt stationary decoders which control polarity to Tortoise switch machines per instructions received over LocoNet. Again, these are left over from my previous model railroad.

My LEWIS Operator will mimick the duties of the LEWIS tower operator, managing the routes and signals through LEWIS interlocking. The protoype model board from LEWIS is preserved at the Lewistown Station by the PRRT&HS. The control mechanism was not retained and is documented as "US&S", "Type P3", "electro-pneumatic" with "24 levers" in a "24 lever machine". I can confirm there were 12 switch levers, 9 signal levers, and 3 traffic levers. I believe the tower contained a US&S Model 14 machine. What is unknown is whether the machine had traditional Model 14 levers (like HARRIS, STATE) or the "pistol grip" type. Perhaps the "P3" reference suggests "pistol grip", but that would be a reach.

On the model railroad, I am representing the LEWIS control mechanism as a US&S 500 series machine. Initially this will be via computer interface, using JMRI's PanelPro module. Once all of the logic is worked out and confirmed, I plan to construct a replica machine. The JMRI to hardware connectivity will likely utilize the Tower Controller product from RR-CirKits.

The duties of the WALL and JACKS tower operators will be combined into a Trainmaster position which will control all movements in and out of staging, in both directions. Control will be via JMRI computer interface, using the Dispatcher  module, but probably PanelPro as a precursor. To simulate the distances between WALL and LEWIS (@ 10 miles) and JACKS and LEWIS (@ 20 miles), once the Trainmaster clears a train to leave staging, there will be a countdown timer before the signal goes active for the engineer of the train. During this time the LEWIS operator will receive notice of the movement from the neighboring tower and may opt to set the route in advance of the train's arrival on station (at LEWIS).

The method of signal control is yet to be determined. The logic is within JMRI, but the field control may utilize solutions from Digitrax or RR-CirKits (or a future contender). 

In summary, the steps towards operation are:

  1. Create track diagram in JMRI Layout Editor for the purpose of establishing logic.
  2. Program occupancy detection as track is installed.
  3. Program switch control as track is installed.
  4. Program signal logic (even through physical signals are not installed).
  5. Create PanelPro representation for Trainmaster for control of WALL and JACKS interlockings.
  6. Create PanelPro representation for LEWIS Operator.
  7. Implement physical signalling on model railroad.
  8. Migrate Trainmaster from PanelPro control to Dispatcher control.

Progress Reports (will be posted here in the future):

The following is a crude diagram of the main line with the occupancy section breaks shown in red. The LEWIS interlocking diagram is from the PRRT&S book on the Lewistown area.

click on image for larger version.