Discussion in 'General' started by Karl, Jun 19, 2010.
This document provides an generalized overview of Frisco mainlines.
Karl - Neat! Thanks for posting.
Though the vertical dimension on the chart is necessarily exaggerated vs the horizontal, it is easy to see how Newburg sits in a hole between Rolla Hill and Dixon Hill on the St Louis to Springfield Eastern Division. That is the valley created by the Gasconade and Little Piney rivers.
I am surprised to see the chart indicate that Iron Hill (St Clair) is indicated to be the ruling westbound grade between St Louis and Springfield and not Dixon Hill. I always thought Dixon Hill west of Newburg remained the ruling westbound grade even after the mid-1940's relocation and grade reduction.
Rolla Hill is shown as the ruling eastbound coming out of Newburg which is what I always understood.
Looking at that chart really brings home the concept that the River Division (other than the climb to Lindenwood from the river and the bridge at Memphis) really was of no consequence in terms of grade. I believe I'd heard that other than those two grades, the running grade was 0.06%!
Iron Hill begins at about MP 45.85 (elev 490.80’) and “flattens-out” near MP 50.4 (elev 753.07’). It consists of a series of short (0.1 mile to 0.2 mile )grade segments, whose gradients range in value from 0.60% to 1.80%.
The new alignment of Dixon Hill begins near MP 123.48 (elev 690.70’) , which is just east (RR) of the Hwy D overpass, and the grade “flattens-out” near MP 133.95 (elev 1209.20’). For most of its length, the grade holds to a max 1.27% but it does “level-off” to 0.27% to 0.67% near Franks. There is a shallow hogback near MP 131.5, where 7 feet of elevation are lost before the climb resumes to Dixon.
I do recall SLSF 1522 seeming to have a bit more of a struggle going up Iron Hill than she did later on the same day on Dixon Hill. There was one turn on Iron Hill, I think it was to the left, that she seemed to shudder a bit. It seemed to me she just walked up Dixon Hill, albeit slowly, later that same day.
Don - can you offer any thoughts on the two westbound hills?
The LH curve at MP 46.7 to MP 47.0 is on the steepest part (1.80%) of Iron Hill. The curve is 4 degrees- 19 minutes and has a delta of 44 degrees.
In the 1955-56-57? era, the Frisco did some more realignment work east of St. Clair. I do not know the mile post. Frisco used its own heavy equipment and personnel to do this work. I know several of the people involved.
Secondly, as I recall, for each degree of curvature it takes an additional lb. of drawbar pull. For each % of incline, it also take an additional amount of drawbar pull but I don't remember the figure. A 10 degree curve,( rare on the main line) and a 3 or 4 % incline really sap the drawpull capability of the prime mover.
Curve Resistance = 0.8 lb per ton per degree of curve
Grade Resistance= 20 lb per ton per 1 percent of grade
Thanks for the additional facts regarding drawbar pull, etc. All I remembered about the grade, it really added up quickly when calculating the dbp required.
Thanks Karl. That is the curve I noticed - I put a small mark there on my track chart during the trip. I can see why 1522 would need a second breath there - well up the hill, entering a fairly sharp 44deg curve to the left, on a steep 1.8% grade, pulling a full heavy train. She kept on working, though, and we made it with no problem.
I wonder how the original E7's on the Texas Special and The Meteor did on that part of the hill with their as-delivered high gearing? I bet they needed to gut it out as well.
A 4+ degree curve is fairly sharp, but not the sharpest on the line - there are a few 5deg and 6deg curves on Rolla & Dixon hills.
The Eastern Division was/is certainly a curvy, hog-back, up and down line. Love it - part of its considerable charm!
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