Eastern Railroad Discussion > Question concerning the NS Pittsburgh Line

When NS implemented PTC on their Pittsburgh line in PA, they obtained permission to eliminate all wayside intermediate signals and rely on cab signals to govern movement between control points.

As part of the wayside signal removal process, NS erected small signal type equipment sheds at roughly the same locations where wayside intermediate signals had been located. Each of these new sheds is identified as “SIP” followed by the Pittsburgh Line mileage location. For example, “SIP 174.5”. My question; what does the SIP stand for?

Thanks in advance for any info!

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Signal Indication Point

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Edited 1 time(s). Last edit at 08/03/20 17:56 by CR6401.

Excellent! Thank you for the quick response!

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The following is also a pretty interesting read as to the purpose they serve:

http://position-light.blogspot.com/2019/11/pittsburgh-line-cab-signal-overlaps-and.html

So it basically enabled NS to double the number of blocks and safely reduce the interval between trains.

That explains why the signal huts don’t exactly correspond with the locations of the former wayside intermediate signals.

Thanks for posting that link!

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