"History of flashing signals aspects !!"

[cacole]

I've noticed the flashing yellow signal on the Union Pacific Sunset Route, formerly Southern Pacific, as west-bound trains approach a bridge over the San Pedro River at Benson, Arizona.

This is the lowest point along the UP line between Lordsburg, New Mexico and Tucson, Arizona, where trains are descending a 5-mile long 1.5 percent grade. As soon as they cross the bridge, they are in downtown Benson and beginning a long climb out of the San Pedro Valley.

I have always thought the flashing yellow was warning engineers that they were going too fast for the speed restriction on the bridge, because they always apply their brakes and slow down when this happens. If a train is already going slow, the light does not flash, but remains solid green until the train reaches it.

[jrbernier]

Flashing yellow aspects on signals have been around since before the 40's. This many times is used as an 'Approach Medium' aspect. The ex-CB&Q triple track line out of Chicago uses this aspect to give a 3 block in advance view....

Jim Bernier

[csmith9474]

I know the Espee used flashing yellow in CTC territory. What I don't know is when this practice began. I believe the flashing yellow meant (and still does) to proceed, and be prepared to take a diverging route at the next signal (which also means to slow it down in preperation of this).

[nambo]

Hello, would anyone know if flashing signal aspects were used on search light signal in the very early 1950s and were they used on wstern railroads durring this time too?