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JimDep
July 18th, 2008, 04:04 PM
Yesterday, I spent some time talking to a UP signal tech that was trouble shooting some crossing guards. I asked him about block signals and yellow lights.
He informed me that a flashing yellow means the speed limit is 40mph in that block and a solid yellow limits the speed to 30 mph. If the speed limit is normally less than 40 or 30 mph within that block, that the engineer would follow the posted speed. For example, if the speed limit is posted at 50mph, and you get the flashing yellow or yellow, you limit your speed to 40/30mph. This rule applies to all UP lines.
This was news to me. Anyone else have input on this?

UPRails834
July 18th, 2008, 07:00 PM
I think you took the signal maintainers explanation a little out of context or maybe he simplified his explanation. A flashing yellow or a yellow signal isn't displayed to limit a trains speed, they are displayed to inform the Engineer to possibly be prepared to stop. With that said I will quote the actual UP rules for the signals you mentioned so you can get a better understanding of the purpose of the speed limits:

Rule 9.2.4 - Advance Approach (Flashing Yellow)
Proceed prepared to stop at second signal. Freight trains exceeding 40 MPH must immediately reduce to 40 MPH. Passenger trains may proceed, but must be prepared to pass the next signal not exceeding 40 MPH. When signal governs the approach to a control point with a 40 MPH turnout speed be prepared to advance on normal or diverging route.

Rule 9.2.6 - Approach (Yellow)
Proceed prepared to stop before any part of train or engine passes next signal. Freight trains exceeding 30 MPH must immediately reduce to 30 MPH. Passenger trains exceeding 45 MPH must immediately reduce to 45 MPH.

Hopefully now you understand what the maintainer was talking about when he mentioned the 40 and 30 mph speeds.

Todd

JimDep
July 18th, 2008, 10:30 PM
Todd,

Thanks for clarifying that.

I remember now that he also mentioned passenger train speeds, but the conversation mostly pertained to freight. Amtrak uses this subdivision only if needed as an alternate route, which is rare.