Where? -- BALL's HOLE

NW Mailing List nw-mailing-list at nwhs.org
Mon Nov 21 18:44:37 EST 2016

On 11/21/2016 4:48 PM, NW Mailing List wrote:

> Another interesting facet of this investigation is the "Mile Post" 
> number for Singer, or any other interlocking. The problem is that the 
> limits of Singer Interlocking, measured between the opposing home 
> signals, is about 1,000 feet long. How do you assign a Mile Post + 
> Tenth to an interlocking like that? Some years ago, when I was working 
> for another railroad, we installed a new interlocking that was a tad 
> over 2,000 feet long and had Main Tracks coming in from three 
> directions. The Signal Department System Office had applied a numeral 
> + decimal for the designation of the exact location of that 
> interlocking, and I asked the Chief Signal Engineer how they arrived 
> at a Mile Post + Tenth for an interlocking that long. The answer was 
> that the location of the Instrument House (signal case) determined the 
> Mile Post numeral designation for the interlocking. Since this 
> particular interlocking had three instrument houses (signal cases) in 
> it, I asked the Chief Signal Engineer how they made a determination in 
> such an instance. The answer was that the largest of the Instrument 
> Houses was considered the "central" one, and the Mile Post + Tenth 
> designation was taken from that one. Interesting stuff that most 
> people never have to deal with or think about!
     A milepost numeral is not needed as far as the signal is concerned 
as it is a control point, NOT an intermediate signal. So, who cares what 
the milepost of the interlocking is? It is what it is + number of feet.

Jimmy Lisle

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