The more you know Wrote:
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www.google.com]
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> UP ex-Julesburg line crossing US 34 east of Kersey, CO. Note the traffic signal for the rail line: 4 lights. Is one for a protected left turn....
I think y'all seem t'ave missed seeing that four-high stack of yellow cylinders, next to the track, that points along the track toward a train approaching the road. It'd be on the train's left-hand side as the train approaches. There's a similar setup (
shown here) across the road for trains approaching from the other direction. I think the OP was asking about those devices, not the the signal lights hanging over the roadway. How are those four-light signals used?