communicate with supervisors. Usually the workers lived in camps built near their work site. Supplies were ordered by the engineers and hauled by rail, possibly then to be loaded on wagons if they were needed ahead of the railhead. Camps were moved when the railhead moved a significant distance. Later, as the railroad started moving long distances every few days, some railroad cars had bunkhouses built in them that moved with the workers—the Union Pacific had used this technique since 1866. Almost all of the roadbed work had to be done manually, using shovels, picks, axes, two-wheeled dump carts, wheelbarrows, ropes, scrapers, etc., with initially only black powder available for blasting. Carts pulled by mules, and horses were about the only labor-saving devices available then. Lumber and ties were usually provided by independent contractors who cut, hauled and sawed the timber as required. Tunnels were blasted through hard rock by drilling holes in the rock face by hand and filling them with black powder. Sometimes cracks were found which could be filled with powder and blasted loose. The loosened rock would be collected and hauled out of the tunnel for use in a fill area or as roadbed, or else dumped over the side as waste. A foot or so advance on a tunnel face was a typical day's work. Some tunnels took almost a year to finish and the Summit Tunnel, the longest, took almost two years. In the final days of working in the Sierras, the recently invented nitroglycerin explosive was introduced and used on the last tunnels including Summit Tunnel. Supply trains carried all the necessary material for the construction up to the railhead, with mule or horse-drawn wagons carrying it the rest of the ways if required. Ties were typically unloaded from horse-drawn or mule-drawn wagons and then placed on the track ballast and leveled to get ready for the rails. Rails, which weighed the most, were often kicked off the flatcars and carried by gangs of men on each side of the rail to where needed. The rails just in front of the rail car would be placed first, measured for the correct gauge with gauge sticks and then nailed down on the ties with spike mauls. The fishplates connecting the ends of the rails would be bolted on and then the car pushed by hand to the end of the rail and rail installation