By: Chris Nuthall. 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.
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.
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.
The original haulage fleet consisted of 32 locomotives (3501 to 3532) supplied by ASEA of Sweden, however in 1978 AMAX ordered four new locomotives of similar appearance from GEC Traction of Manchester, UK, due to ongoing issues with the ASEA fleet. This was apparently the first time that complete electric locomotives had been supplied to the USA from the UK and the first time for a long while that a British company had supplied a locomotive of any type to the USA.
The four locomotives were delivered from 1980 and were numbered 3533 to 3536 - they also had the distinction of being the very last locomotives to be built at the Vulcan Foundry at Newton le Willows, between Manchester and Liverpool, UK (Works Nos. 5590 to 5593). They were dual voltage; chopper controlled of a two-axle rigid design with two nose suspended 460kW (616 hp - continuous rating) G415BY traction motors similar to those supplied for the 7E 50kV AC ISCOR locomotives in South Africa.
With approximately 4-inch thick steel for the frames, the locomotives weighed in at 62 tons each, with almost 47 inch diameter wheels and a length of 25 feet 3 inches. The locomotive featured both dynamic and regenerative brake, enabling them to put power back into the overhead line while traveling down the tunnel in braking mode.
The haulage capacity was approximately 50% higher than that of the ASEA locomotives, demonstrated on one occasion when a locomotive on a preceding train failed and the two GEC locomotives rescued the disabled train in the tunnel, effectively hauling their own loaded train of 16 ore cars, plus a third of the preceding train’s 22 ore cars and a dead locomotive. In an early test, two GEC locomotives accelerated a fully loaded train of 16 ore cars from zero to 25 mph on the 3% grade in 2,000 feet.
The GEC locomotives did not live up to their expectations and a series of modifications were carried out, which led to improved reliability.
The first full day of ore haulage using these locomotives occurred on 31 July 1981, using locomotives 3533 and 3535, with 15 or 16 ore cars, with 3534 as standby. The final locomotive 3536 arrived in Denver at the end of 1981 and delivery to the mill site occurred early the following year. All four locomotives were operational by February 1982 and three locomotive trains with 21 or 22 ore cars were regularly run, although some three-locomotive test running had taken place before the arrival of 3536.
A serious downturn in the industry saw the mine and mill closed in October 1982 and the locomotives put into storage. The mine reopened in January 1984 and the locomotives were reactivated for a further period of service.
By the end of July 1999 the haulage system ceased operation and was replaced by an elevated conveyor, one of the longest of its type in the world, which basically ran up the tunnel and followed some of the original railroad formation to the mill. The haulage system was cut up for salvage in 2000, with two of the original ASEA locomotives being preserved, 3517 at the Western Museum of Mining & Industry, Colorado Springs and 3524 at the entrance of the Henderson Mill site itself.
The four GEC locomotives also lasted until the end and were disposed of in the same year. The author was on the UK commissioning team for the GEC locomotives for a year from April 1981 and experienced many interesting trips into the tunnel, riding "shotgun" on the GEC locomotives. Much of the article is from memory so any corrections would be gratefully received.
Copyright © Chris Nuthall. All Rights Reserved. Used with permission. Thank you Chris.
LINK: To see more of Chris Nuthall's railroad photography, visit the "CN Rail Gallery".