i am curious what & how hold signals on new crossovers on double track as example between mo valley & denison ia. and beyond, what is the advantage over no hold signals on tri lites, they are always 1 & 2 blocks before actual crossover.
[#welcome], iowa-rr-fan. If I understand you correctly, you’re wondering why a train would hold one or two blocks before the crossover instead of right at it? I would guess that holding at the crossover might block grade crossings. The real authority here on that section of the UP would be jeffhergert, as he runs that stretch all the time as an engineer. Hopefully he’ll spot this and contribute.
i thank for your reply, i was trying to inquire as to the use of these hold signals, the single light below the tri light heads always put at least 1 block before the actual crossover signal, up has them out on the main from omaha west that i assumed was older installations, i very seldom have seen them used or illuminated, now they have added them to the newer double track from mo valley to denison and beyond. i railfan this stretch often in my travels on hwy 30.
Oh, OK, I gotcha. I don’t think we have those on this side of the state, but I seem to recall a discussion in another signal-related thread that touched on that sort of signal arrangement- perhaps you could try a search of the forum on a few key words related to signals. If that don’t work, we’ll just wait for Jeff, I know he’ll be able to answer your questions, unless someone else jumps in!
Ah, yes, Highway 30, my favorite highway.
The signals you are seeing on the with the single light head below the three light head are used for crossover movements at the newer 50 MPH crossovers. The older 40 MPH crossovers are still protected by signals with single tri light heads.
The only time that single bottow head is lit, and it displays only a green light, is when a train is lined up to crossover. There are usually, there are a few exceptions, two blocks with these dual headed signals. The progression is: 1st signal Yellow over Flashing Green. That’s an Approach Clear 60. Proceed not exceeding 60 MPH passing next signal. 2nd signal will be a Yellow over Green. That’s an Approach Clear 50. Proceed not exceeding 50 MPH passing next signal. The 3rd signal will be at the crossover (Control Point) and will be a diverging signal indication, either a Red over Green, Diverging Clear or a Red over Flashing Yellow, Diverging Advance Approach.
Some of the older signals along the UP around Omaha and elsewhere, with only a single light bottom head will display a yellow light when lit. That bottom head also is normally dark unless lined up for a crossover move. Those older ones will be yellow over yellow, Approach Diverging. While they don’t specify a speed, other than “prescribed speed thru the turnout,” they usually are used with 30 MPH crossovers.
Jeff &nb
I think the new crossovers between Bertram and De Witt have 50 MPH crossovers and should have the same kind of signal arrangement. Next time your over around Mechanicsville, check out the west bound block signals. There is a set of crossovers (CP Koch, I think) about a mile west of where US30 comes near the railroad. If the crossover is good for 50, the block signals approaching the CP should have a single bottom head under the normal tri light head. I can’t say where those signals are at, the last time I went that way there were no wayside signals in that area, but at least one should be visible from the highway.
Jeff
I thank you for your very informative reply, it makes sense now, its another way that dispatchers can limit by signal speeds of trains, and with all the new crossovers UP put in on west Iowa track with swing nose high speed crossovers. I seldom get any further than Ames or I-35 to the east. I wasnt sure but figured that they were working east with crossovers and signals into east Iowa due to coal & stack traffic loads dominate origin from the west. Anyway will have watch for the signals now that I know more. I have been lucky to get to Gibbon jct a couple times a year, amazing amount of tonnage splits to KC. UP uses both tracks from Mo Valley, still running C&NW left hand, in spots because of concrete ties I assume.
I guess I better pay closer attention- of course whenever I’m down that way I’m usually behind the wheel and 30 is just two lanes- scares the you-know-what out of my wife when I gawk at the rail traffic!