Why does SLE slow down between Branford and Guilford?

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NH2060
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Why does SLE slow down between Branford and Guilford?

Post by NH2060 » Wed May 16, 2012 8:39 pm

Every time I've ridden SLE going eastbound (which hasn't been in a while so correct me if things have changed) the train always slows down to, literally, a crawl at the exact same straight stretch of track about a mile or so west of the Guilford station on a high embankment/fill alongside Route 146. Is there a reason for this? I've always guessed that it was because if the train were to derail on that segment the force of the engine pushing would create a truly catastrophic wreck (to the best of my recollection I've never been on a westbound SLE train or an Amtrak train that slowed down at the same location).

The EGE
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Re: Why does SLE slow down between Branford and Guilford?

Post by The EGE » Wed May 16, 2012 9:59 pm

146 crosses the shore line in two places. There's a limit of 75mph for loco-hauled trains on the curve near the east crossing, and 80mph near the west crossing, with 95mph between them. (The rest of the area has 100 and 100 limits for loco-hauled trains, and 120 for the Acela). But SLE isn't moving much if any faster than 80 anyway. Other than that, I can't help you.

theozno
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Re: Why does SLE slow down between Branford and Guilford?

Post by theozno » Thu May 17, 2012 1:50 am

The EGE wrote:146 crosses the shore line in two places. There's a limit of 75mph for loco-hauled trains on the curve near the east crossing, and 80mph near the west crossing, with 95mph between them. (The rest of the area has 100 and 100 limits for loco-hauled trains, and 120 for the Acela). But SLE isn't moving much if any faster than 80 anyway. Other than that, I can't help you.
It will be interesting when the M8 run this stretch of Track
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The EGE
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Re: Why does SLE slow down between Branford and Guilford?

Post by The EGE » Thu May 17, 2012 6:41 am

Same restrictions on multiple units. Only high-speed trainsets with active tilting are allowed full speed there.

NH2060
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Re: Why does SLE slow down between Branford and Guilford?

Post by NH2060 » Thu May 17, 2012 9:41 am

The EGE wrote:146 crosses the shore line in two places. There's a limit of 75mph for loco-hauled trains on the curve near the east crossing, and 80mph near the west crossing, with 95mph between them. (The rest of the area has 100 and 100 limits for loco-hauled trains, and 120 for the Acela). But SLE isn't moving much if any faster than 80 anyway. Other than that, I can't help you.
Oh it's definitely not a speed limit issue (I didn't know Acelas were good for 120 through that stretch! :-D). The EB SLE trains I were on would move no faster than like 10-15mph through that part of the track and then speed up after crossing 146 the last time.

RearOfSignal
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Re: Why does SLE slow down between Branford and Guilford?

Post by RearOfSignal » Thu May 17, 2012 2:45 pm

It's the signal system that requires the trains to slow down before a stop signal.

This was discussed previously(here... http://www.railroad.net/forums/viewtopi ... 56&start=0), there are several pages to the thread that explains it pretty well.
Hurry up and wait at the signal!

NH2060
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Re: Why does SLE slow down between Branford and Guilford?

Post by NH2060 » Thu May 17, 2012 4:46 pm

RearOfSignal wrote:It's the signal system that requires the trains to slow down before a stop signal.

This was discussed previously(here... http://www.railroad.net/forums/viewtopi ... 56&start=0), there are several pages to the thread that explains it pretty well.
Ok that explains it, thanks!

amm in ny
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Re: Why does SLE slow down between Branford and Guilford?

Post by amm in ny » Fri May 18, 2012 9:51 am

RearOfSignal wrote:It's the signal system that requires the trains to slow down before a stop signal.

This was discussed previously...
If I understood the discussion correctly, the issue is that the block that includes the station is long, and since the signal at the end of the block is at "stop", the train has to travel the entire block at "approach" (or whatever the next level up from stop is.)

If so, could the problem be reduced by splitting up the block? (I recognize that the signalling might have to be more complex -- additional aspects, or multiple blocks showing the same aspect, or whatever.)

Note that I am not saying that Amtrak and/or CDOT should actually spend the money to do this.

RearOfSignal
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Re: Why does SLE slow down between Branford and Guilford?

Post by RearOfSignal » Fri May 18, 2012 1:46 pm

Yes but splitting the block would provide less time for a train traveling at MAS to comply with a signal downgrade. To compare traffic lights where the speed limit is 30 mph may have a 5 second yellow light. But a traffic light on a highway with a speed limit of 55 mph may have a 8 second yellow light. The point being you have to provide signal blocks long enough that it allows for all trains to safely comply to the signal indication given factors such as train speed and braking capabilities.
Hurry up and wait at the signal!

amm in ny
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Re: Why does SLE slow down between Branford and Guilford?

Post by amm in ny » Sat May 19, 2012 12:42 pm

RearOfSignal wrote:Yes but splitting the block would provide less time for a train traveling at MAS to comply with a signal downgrade.
1. Isn't this the sort of thing that additional aspects are intended to handle?

2. It sounds from what you are saying that a train is allowed a full block length to reduce its speed to the speed specified by the restricted signal. Somehow, I envision the engineer saying, "there's a yellow signal, I have until the next signal to get my speed down to 10 mph" (or something like that.) Am I understanding this correctly? Or is the engineer required to get the speed down to 10mph (or whatever) before (s)he passes the yellow signal?

Finally, wouldn't Amtrak trains have the same problem as the SLE trains if the same signal were red when they approached Guilford?

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