CTC Dispatching form of Train Control
Centralized Traffic Control (CTC) was invented in the 1940's and began deployment in Michigan lines shortly thereafter.
This is a type of railroad signaling and control for trains. Early CTC installations covered a small section of track, usually less than 50 miles, which was controlled by a local nearby operator. As the technology improved, this equpiment could be operated from farther locations and dispatchers took over this responsibility. Today, CTC installations can be operated remotely from anywhere in the world, though most are controlled now by regional dispatching centers.
CTC control panels originally were large analog consoles which track diagrams, switches, indicator lights and buttons. Now 70 years later, they displays are on video computer monitors and controlled by keyboards. Originally, when the CTC operator pushed a button made some type of change, the CTC "machine" put out a pulsating code over a "code line" along the track. Each control point sensed its own code, made the change, and sent pulses back to confirm the setting. The CTC logic and the control point logic prevented setting unsafe or improper routes.
The one concept in CTC which has existed from day one an continues is that the control point in the field continues to operate even if it is disconnected from the CTC machine or the centralized dispatching software. This fail safe operation protects trains, crews and the public in case of communications failure or some type of other mistake.
Note: Just because a railroad track has signals, it does not mean that they are controlled by Centralized Traffic Control. Many of these installations are Automatic Block Signals (ABS) - sometimes in one direction and in other cases bi-directional. ABS warns train crews of trains ahead and prevents collisions but the dispatchers do not control the signals. Many CTC systems use a combination of CTC and ABS. As an example, the CTC will control the passing sidings and control points, but the signals in between are automatic (ABS).
The CTC panel/display allows dispatchers to keep track of train locations across their territory.
CTC Locations in Michigan and Surrounding Areas
These are the known lines in Michigan eventually controlled by CTC. The listing indicates the owner railroad when the CTC was installed.
Main Line from West Detroit to Town Line (Dearborn) was added - controlled by dispatcher.
Main Line from Town Line (Dearborn) to Kalamzaoo - controlled by dispatcher. Single tracked at this time.
Grand Trunk Western
In 1974, CTC on the Flint Sub from West Tappan (Port Huron) west to East Flint, from West Flint to East Durand, from McAllister Road (east of Battle Creek) to Emmett Street. On the Holly Sub from M.A.L. Junction (Pontiac) to Durand (CTC controlled by dispatcher at Pontiac Yard).
New York Central
New York Central Air Line - OD interlocking in Jackson to White Pigeon, MI - controlled by the Jackson East dispatcher.
Main Line from 15th Street to West Detroit - controlled by the tower operator at West Detroit. This resulted in the closure of 15th street, 20th street and the Bay City Jct. leverman towers. Later moved to the Conrail dispatcher and West Detroit was closed.
Pere Marquette / Chesepeake & Ohio
Waverly to St. Joseph - originally controlled by the operator at Waverly. Later transferred to the dispatcher.
Sunnyside to Lake Odessa - originally controlled by the operator at Elmdale. Later transferred to the dispatcher.
Plymouth to Ensel (Lansing) - controlled by dispatcher.
Sunnyside to Porter, IN - controlled by dispatcher.
Plymouth to Midland - controlled by dispatcher. Later cut back to Mershon Tower in Saginaw.