If it is any help in answering some of your queries, I looked up the maximum gradient on the rack sections of the
old route of the Furka-Oberalp Railway - the Swiss metre gauge line for which the Viet Nam locos were designed. The FO had a maximum gradient of eleven percent. Its steam locomotives were designed to operate at 12 mph on rack sections and could reach 30 mph on adhesion sections. I assume this is close to the specs for the repatriated Vietnamese steamers.
The summit tunnel at Furka Pass on the FO's
former route was at an elevation of 7,088 feet. The railway climbed 4,887 feet to reach that summit. Winter operations over the pass were impossible due to extreme avalanche danger and snow clearance issues - so, each fall, the FO suspended operations on that section. Avalanches also required that the catenary be taken down when service was suspended and reassembled in the spring. Incredibly, a bridge spanning Steffenbach Gorge, a notorious avalanche run, was also designed to be dismantled each autumn. Due to it's unique design it took FO crews just two days to reassemble this rather significant span in the spring. (During the winter it was stored on site on either side of the chasm.)
The survival of the FO's last steam locomotive - No. 4, a rack and adhesion compound 2-6-0 - along with a self-propelled steam rotary, were due to the seasonal nature of the Furka Pass operation. Work trains to remove and re-erect the overhead current collection system could not employ electric locos. So each May, No.4 would be steamed up at Oberwald to handle the snow removal and wire trains. It normally took about three weeks to restore the overhead. The 4 would would be called out once more in the fall to handle the shut down process, and it was occasionally used for summer enthusiast trips.
The costs to support this operation must have been staggering. Like other grossly uneconomic rail operations, it was inevitable that the party would end. In 1981, the FO Furka Pass line was replaced by a lengthy tunnel - the second longest narrow gauge tunnel in Switzerland. Now, FO service is year round -- and travelers ride far below the forbidding summit of Furka Pass.
An enthusiast group took over 18 km route over the pass from Realp to Gletsch and Oberwald and gradually restored the entire route for steam excursions in the summer. So not all is lost.
Edited 2 time(s). Last edit at 01/05/2010 10:13AM by Eugene Blabey.
