Another Michigan Line Signal Question

[chapmaja]

I noticed something today as I was watching NS B25 go EB through Dexter from the Dexter Library.

To the west of the library is the signal I have referenced before.

It was showing red (for WB traffic) as B25 was approaching from the west. Once B25 went by the signal, the signal aspect changed to green and stayed this way for a few minutes, before going dark.

I am just a little shocked, with as advanced as the signally systems are, that the signal would turn green even if no train was approaching the block. I would expect the entire system would include a directional component for trains, but it appears this system does not have that component.

[SD80MAC]

That's how nearly all intermediate automatic block signals work. Once a train clears the block, the signal will display the condition of the block the train just came out of, in this case "clear". Most will then shut off when the train clears the next block. Red would indicate there is something else (ie another train) in the same block, or that there is a broken rail or something else fouling the continuity of the block. Yellow would show that the block is clear, but the next one behind it is not (approach, prepare to stop at next signal).

[justalurker66]

In an automatic block signal system that signal behind the train probably would have stayed red due to rules in place concerning reversing the direction of trains.

On CTC the signals can be honest. No train or obstruction in the next two blocks behind the signal and green can be displayed. If the next signal is a controlled point that would need to be cleared by the dispatcher (and often signals are set for the next WB after an EB clears an interlocking). If the dispatcher has already cleared a train through the next controlled point to the west (in this example) the signal would have remained red.

[chapmaja]

So this brings up the next question. Where are the signals between Ann Arbor and West End Chelsea siding on the line?

I know there is one where the old yard in Ann Arbor was just west of the station around the curve from the station. I know there is one just west of the Zeeb Road crossing, one just west of the library in Dexter, then you have the signals governing the east end of the Chelsea siding, a signal in the middle of the Chelsea siding, and the signals on the west end of the Chelsea siding.

I feel like there should be at least 1 more between AA and Dexter and 1 more between Dexter and Chelsea siding, but I don't recall where they would be.

[Standard Railfan]

So this brings up the next question. Where are the signals between Ann Arbor and West End Chelsea siding on the line?

I know there is one where the old yard in Ann Arbor was just west of the station around the curve from the station. I know there is one just west of the Zeeb Road crossing, one just west of the library in Dexter, then you have the signals governing the east end of the Chelsea siding, a signal in the middle of the Chelsea siding, and the signals on the west end of the Chelsea siding.

I feel like there should be at least 1 more between AA and Dexter and 1 more between Dexter and Chelsea siding, but I don't recall where they would be.

The link below will take you to the last edition of the Conrail Michigan line track chart. Chelsea is on page 68 (page 113 of the PDF). You can find the signals on the chart. I don’t know how much has changed since 1999, but I wouldn’t expect a lot of difference.

http://multimodalways.org/docs/railroa ... 201999.pdf

[chapmaja]

In an automatic block signal system that signal behind the train probably would have stayed red due to rules in place concerning reversing the direction of trains.

On CTC the signals can be honest. No train or obstruction in the next two blocks behind the signal and green can be displayed. If the next signal is a controlled point that would need to be cleared by the dispatcher (and often signals are set for the next WB after an EB clears an interlocking). If the dispatcher has already cleared a train through the next controlled point to the west (in this example) the signal would have remained red.

So I saw something else interesting today with the same signal. Here was the sequence of trains from roughly 7 pm to 8:45 is through Dexter.

Shortly after 7 pm, WB Amtrak. This had a green siginal for WB until passing the signal before it clicked to red as the train passed, which makes sense.

A little while later, NS went WB with a middle length freight (sorry no numbers because is was dark.).

A while later I noticed the siginal was showing red, after being dark. When I looked on track a train on Amtrak's site, I didn't see anything. suddenly I see a headlight passing the siginal. Amtrak was heading EB.

What was strange was the siginal stayed red even after the train had passed through Dexter (but likely wan't to the next siginal). It later switched to green.

The only thing I can think of to cause this would be the position of the NS freight when Amtrak cleared the siginal. If they were in the Chelsea siding would this impact the aspect shown for WB traffic in Dexter. The signal I see looks to be 47W and there is a 49W before getting to CP Lake. The NS freight would have had to clear CP Lake for Amtrak is pass in the Chelsea siding. (the NS could not have made Jackson, so the meet had to be in Chelsea Siding).

From an operational standpoint, I can't see anthing that would cause such a delay in the changing of siginal, which normally seems instantaneous with the train passing a signal.

[DaveO]

You have to consider the possibility that something(maintenance of way) entered or left the (former) Chelsea Grain Siding.
It has an electric lock and derail.
CP Lake is now CP 52 according to the google image.
The mile post number attached to the signals means they are ABS signals.

[chapmaja]

I feel very confident that nothing would have been in or out of the Chelsea Grain siding at this time during the day. If this happened during the middle of the day, it is possible, but not at 8:00 plus in the evening.