Re: Deciphering ICC Valuation Maps

Posted by Dave Eggleston on Jun 21, 2021; 12:10am
URL: http://c-sng-discussion-forum.254.s1.nabble.com/Deciphering-ICC-Valuation-Maps-tp16756p16759.html

"The "1776+22 with the raised 0 is the station number for the tank location."

Yes, and the raised number refers to a tenth of a foot. So read that as station 1776 + 22.0' when looking at these maps, which is shorthand for 177622.0' (not 1798.0'!) from station 0 (Buena Vista in 1918). Every 1000 feet the count restarts, so everything between 177600.0 and 177700.00 is 1776+xx.x, where xx.x is the distance in feet and tenths of a foot from 1776+00.0.

The 15 is the tank diameter [edit: I originally incorrectly stated "radius"].  It says "15' W. Tank" which in this case means 15' diameter [edit] water tank. A whistle sign would be called out on its own, follow along the line and you'll likely find one.

The triangle is "delta" or the change in the line from one tangent to the next. It refers to the degrees and minutes the curve runs through on a circle. So delta 90 would be 90 degrees of arc of a full circle. Woodstock curve shows delta 228 which is 228 degrees of arc!

I just noted a really interesting detail on this particular division's maps that can also cause confusion. The mileage increases from 0 to 32 westbound from BV to the tunnel apex at 1565+60, then at the apex of the tunnel the westbound footage is reset to 1566+00 AND the mileage posts DECREASE heading to Gunnison (0) even though the surveyor's footage increases westbound! So if you only look at the ICC map's MP for Tunnel Gulch, you'd think the tank is 24.25 miles from BV becuase it's between MP 24 and 25. But you'd be wrong. In fact you're about 4.75 miles west of the apex, putting you about MP 36 if you measured from BV!

Also, these mileages will vary based on relocations of the line between 1881 and 1918 so not all timetable mileages will map exactly to the ICC map.

Confused yet?