KYLE RR - Utah 5006 West symbol SALI-08, west of Vona, Colorado_
Westbound Salina - Limon freight passes a Rock Island RR-era searchlight signal. In 1946 an ABS type signal system was completed on 485 miles of track between South Omaha, Nebraska and Limon, Colorado. It was a "poor mans" version with station to station blocks at roughly eight-mile increments. This reduced the costs of placing more signals to protect shorter blocks. Blocks in excess of the eight miles did receive a set of intermediate signals half the distance of that block. Single approach signals warning of each of the station-entering signals were placed at an appropriate braking distance in advance of each station. The Rock's signal engineers at the time were looking at the system's use more for speed and cost effectiveness than traffic capacity.
I hope this condensed explanation is coherent enough. It is put together from a book in my collection "Rock Island Westward" by T.R. Lee, and from a very detailed article in "Railway Signaling" sent to me by my friend Ron Wesolowski.
KYLE RR - Utah 5006 West symbol SALI-08, west of Vona, Colorado_
Westbound Salina - Limon freight passes a Rock Island RR-era searchlight signal. In 1946 an ABS type signal system was completed on 485 miles of track between South Omaha, Nebraska and Limon, Colorado. It was a "poor mans" version with station to station blocks at roughly eight-mile increments. This reduced the costs of placing more signals to protect shorter blocks. Blocks in excess of the eight miles did receive a set of intermediate signals half the distance of that block. Single approach signals warning of each of the station-entering signals were placed at an appropriate braking distance in advance of each station. The Rock's signal engineers at the time were looking at the system's use more for speed and cost effectiveness than traffic capacity.
I hope this condensed explanation is coherent enough. It is put together from a book in my collection "Rock Island Westward" by T.R. Lee, and from a very detailed article in "Railway Signaling" sent to me by my friend Ron Wesolowski.