By Chris Nuthall
Posted May 29, 2009
The Henderson Mine Railroad, high up in the mountains west of Denver, Colorado, was unique when compared with regular railroads in the US - it was narrow gauge, electrified, used two axle locomotives in push-pull formation and, at the time, boasted the longest railroad tunnel in the US - albeit with only one portal. The line was the dedicated haulage system for the AMAX molybdenum mining and processing operation at Henderson, which, in 1980 was the largest single producer of molybdenum concentrate in the world.
The railroad linked the American Metal Climax (AMAX) Henderson molybdenum mine, located under Red Mountain near Empire, west of Denver, with the processing mill on the other side of the Continental Divide, about five miles off Highway 9 between Silverthorne and Kremmling, on Ute Pass Road. Commissioned in 1976, by 1980 Henderson was the world’s largest single producer of molybdenum ore, mining, hauling and crushing some 4.6 million tons of ore to produce 25,000 tons of molybdenum concentrate per annum.
The railroad was of 3 foot 6 inch gauge double track and electrified to 1,400V DC. It ran for 15 miles from an elevation of 7,500 feet, with the first 10 miles of dead straight 3% rising grade in tunnel (the longest tunnel in the US at the time), then a further 5 miles on an easier 1.3% rising grade from the tunnel Portal, winding up the William Fort Valley to the Crusher at the Mill site, elevation 9,500 feet. The maximum speed on the railroad was 25 mph.
At the bottom of the tunnel the line leveled out and took a turn to the right along what was known as the "hanging wall" before branching off into the various loading drifts, the ore being mined from various levels up to 400 feet above the loading area. Just before the start of the hanging wall the overhead voltage was dropped to 600V DC for safety reasons.
3533 inside a loading drift in the depths of the mine
There was a ventilation shaft (Vent Raise) located halfway up the tunnel. With air temperatures at the bottom up to 100 degrees F, even in winter, and the Portal temperature down as low as -20 degrees F, the temperature gradient at the Vent Raise could be quite severe, with high humidity air coming up from the mine.
Ore trains were set up with usually two locomotives (locally known as locies or lokies) at the mill end and one at the mine end with about 22 ore wagons in between, connected by a six-wire Intra Train Communication (ITC) system which ran through each ore car. Occasionally 30-car trains were run with two pairs of locomotives.
Loaded train stops to confer with the operator of GEC Train at the Portal
The mill site was self-contained as far rolling stock maintenance was concerned, with a combined "loci" shop and car barn, each fitted out with inspection pits and cranes, situated just before the crusher, where the loaded ore trains were discharged. Beyond the crusher was the tail track, three sidings where trains reversed for another run down to the mine to load, or for remarshalling to remove bad order locomotives or cars.
The haulage system worked around the clock; except on planned shutdown days and each train could run up to 8 or 9 return trips in a 24-hour period. For switching, the site had four small diesel locomotives, a number built by Plymouth.
A pair of Plymouth diesels take 3533 and 3535 to the tail track after repairs
Part 2 continued on the following thread