Around here in Phoenix and out along the main Sunset Route, UP uses alot of “target signals”. One light, that shows 3 different colors. I got the green, got the red. but the 2 that I am not sure of is yellow and flashing yellow.
I assume yellow means “go slow” or proced under a speed restriction, but the flashing yellow has me wondering…
Any in insight would be appricated.
Thanks gang.
The Phoenix line uses permissive block signalling. I haven’t seen a flashing yellow aspect on the east end of the Phoenix line, but the standard applies - green Proceed, yellow Approach and red is Stop and Proceed at Restricted Speed, though I have seen trains blow a red signal at restricted speed before.
The way these lights have generally been set up (as under SP, nothing has changed), if a train is 5 ABS blocks out, you have a Green (dark if no train is occupying the block for the clear), 4 blocks out you get the Approach, and 3 blocks out you get the Stop and Proceed. The only exception is yard limits on the Mesa yard (between Extension Rd and McDonald Rd), signals on the blocks either side will display Approach in the direction of the yard if a train is in the yard or preceeding blocks, unless a train actually enters that block which is protected by that signal, which will then display Stop and Proceed - the signals being at Dobson Road and also at McQueen, railroad east of Southern Ave on the west end of McQueen siding (yard limit signals at Extension Rd on the west end and McDonald on the east end).
The standard is. Green - Proceed, Flashing Yellow - Proceed prepared to stop at second signal, trains exceeding 40mph, immediately reduce speed to 40mph, Yellow- Proceed prepared to stop at next signal, trains exceeding 30mph, immediately reduce speed to 30mph. Red (with a number plate) Stop and proceed at restricted speed. Red (without a number plate (also called an absolute signal)) Stop. There are some exceptions to these rules particularly with regards to red number plated signals.