A "model board" is a display of tracks, blocks, signals and switch locks in an interlocking tower or junction. In typical two-story towers, the model board is large and usually hangs over the interlocking plant levers. Town Line was a much smaller operation, without manual interlocker switch controls.

The model board at Town Line was about 2 feet high and 3 feet across, and was located on the desk top to the right of the operator, just below the bell decoders. The model board was pretty simple. Each direction had two "bells" or lighted enunciators which lit and rang when a train entered the focus of the interlocker. The first eastbound bell was in what is now known as West Dearborn, near Greenfield Village. The second eastbound bell was within headlight sight of the tower east of the Southfield Road (expressway).

Westbound enunciator bells gave a similar warning of approaching trains from the Detroit area. The first westbound bell was somewhere near Central Avenue in Detroit, near the Junction Yard hump. The second westbound bell was somewhere near the Miller Road overpass (C&O overpass/Detroit Terminal Railroad connection).

To clear a train through the interlocker, the operator had to first make sure that switches were lined correctly. If a switch needed to be thrown, the operator had to first release it's lock on the model board and then go outside. Near the switch was a silver box stand with a door. The operator opened the door which revealed a knob lever. The operator moved the lever to the unlocked position before manually turning the switch. Sometimes the knob lever would not unlock, meaning that something in the interlocker was not set properly for this movement or their was a malfunction in the system. The switch could not be moved without the proper release of the lock. If the operator removed a permissive signal, and immediately tried to unlock a switch, their was a timer present that required a wait of five minutes or so before the lock would work. This allowed any oncoming train that couldn't stop, time to go through the interlocking plant.

After the switches were lined correctly, the operator then returned to the shanty and pushed in the button of the correct signal to give a "clear" or "permissive" signal. Clear was used for main line runs, permissive for entrance into the yard or through crossovers. The plant would not allow a clear signal to be given for a diverging route. It should be noted that if a S.D. ("stop displayed") donut ring was resting between the two signal buttons (permissive and clear), the operator could not push either switch. This was a reminder that the dispatcher had ordered a S.D. to protect an opposing movement in the block ahead (common for yard pulls at Miller Road).

The eastbound train order signal (which physically existed) was never used. Train orders within Detroit yard limits were not used in the early 1960's. (Westbound train orders were used and the yellow train order signal was turned on by a switch in front of the operator near the east window. The signal itself was mounted on the east side of the shanty. The unused EB train order signal was mounted on the EB interlocking signal mast, to the right of the top light.).

It should be noted that both of the westbound and eastbound signals were made up of three light instruments (mounted vertically one on top of the other). The operator had only two controls for the signal, but the signal would display other signals (such as a high yellow, indicating permission to proceed on the main track, with the next signal expected to be red).

The two interlocking signals on the main tracks were accompanied by automatic train stop. This was an inductive sensor bolted to the right side of the tie about 100 feet prior to the signal mast. If the signal was red (stop) and the engineer drove past the signal, the automatic train stop would put the train "into emergency", apply the brakes and turn off the throttle. If driving past the red signal was planned (because of a signal failure), the engineer had to hold a lever down while passing over the sensor to avoid putting his train into emergency. Consequences for passing a red signal without overriding it were severe. In addition to having to answer to trainmasters and foremen, the train brake system itself had to be repumped before moving - a process which could take 15 or more minutes. Try explaining that delay while fouling the interlocker!

Arriving trains on opposing tracks (i.e. a westbound train arriving on the eastbound track) did not have signals in the early 1960's and required a hand signal from the operator at Town Line prior to entering the interlocker. The same held true with westbound trains leaving the Advanced Departure Yard, or the old and new wye's. They also needed a hand signal. They also were prohibited from entering the main line by a derail which was controlled simultaneously by the junction switch. A derail was a steel flange which lays on top of the track when deployed. A train driving over a derail would do just that - derail!

My memories of the model board are somewhat hazy. I don't think that there were enunciator bells for opposing main tracks or the wye tracks but I am not positive about this. In the mid-1960's, the model board was replaced by a new, smaller model board which I believe was yellow in color. This may have been when pot signals were installed for opposing movements and movements from the old and new wye. I'm not sure.

Town Line tower was eventually remote controlled from West Detroit tower, and then by the Conrail Dearborn dispatching center.