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[quote user="riprap"]Hi, 1435-- Thanks for weighing in on this one, and I never thanked you for your very thoughtful and detailed response to one of my previous questions on the block signals.  Well taken!! To answer a thought you had above with a possible answer, I lived in the Portland, OR metro area for several  years, and UP has taken over virtual control of all lines going out south and east.  All of the "pole lines" on the Eugene-bound line and all of the pole lines on the Graham Sub (all PDX-bound traffic from the East) have been removed.  The lines from the Kenton Sub (mostly Kalama, WA- or Seattle-bound traffic) have just recently been removed.  The one place I still see them are in the Columbia River Gorge, and perhaps all of those advanced technologies you refer to still cannot penetrate the narrow corridor through there.  It sounds like they too will meet their end.  From a safety point of view, one of the reasons I appreciated having the pole lines there was that they informed me the rail line was actually busy enough that I should probably use more caution when crossing the tracks.  Of course, if there were no pole lines before, the level of traffic was most likely neglible enough that less caution needed to be used. FWIW.... Riprap[/quote] I'm familiar with the UP through the Gorge and it's not THAT narrow.  It would be very easy to get good RF propagation there, and I expect UP already has it just to support their VHF radio.  The more plausible explanation for the continued use of a pole line in this location is that the signal system was renewed at a relatively late date and isn't yet due for another renewal. To explain:  When a signaling system was installed de novo, historically, a pole line had to be created (or usually heavily upgraded) at that time.  Until the 1970s a pole line was pretty much an absolute requirement.  Signaling systems last a long time, and as a rule the pole line doesn't come out until the same time you upgrade the signaling system to a through-the-rail or RF system.  Any signaling system renewed after the 1970s generally went to a through-the-rail or RF system in lieu of a pole line.  The signaling systems currently being replaced are the ones dating to the 1940s and 1950s.  Those that were installed in the 1960s and 1970s are usually not the priority for replacement since they're not so obsolete and expensive to maintain as the older systems.  Having some knowledge of UP signaling installation dates stuck in my head, I recall that Troutdale-The Dalles was renewed in the 1960s or thereabouts, which would be why it hasn't been a priority for renewal like the other lines you mention. S. Hadid
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