weld pipe, and a small amount of thick seamless pipe. In total, 21,185 railcar loads of steel piping were laid during the project, the Big Inch alone requiring of steel. The pipe was laid in trenches deep and wide, dug out by a combination of ditching machines and manual labor. The pipes were then cleaned by pulling a workman through the inside of them with cloths, and welded together, using both the "stovepiping" method and the roll-weld, or "firing line", methods. Stovepiping was an older method, in which the welder worked his way around two pipes, which remained stationary; the newer roll-weld approach instead rotated the pipes, allowing the welder to remain in one position as he worked, with up to seven pipes being welded together at the same time. Where it was necessary for the pipeline to curve to fit the route, the steel pipes were bent, using either a cold-bending approach, in which tractors would pull and push the pipelines into position, or a hot-bending method, with the pipe heated up by blow-torches and pulled into place using a jig. A new, specialized piece of equipment for bending pipes, the Cummings bending jig, was invented during the Big Inch build, and used on the construction of the Little Big Inch pipeline. To protect the pipeline from corrosion, its outside was then cleaned by machine, and painted in first a layer of coal tar enamel, and then hot coal tar coating, before being wrapped in asbestos felt. Finally the pipeline was lowered into position, taking care not to damage the ends of the pipes; the larger pipes were so heavy that they required a D-8 caterpillar tractor equipped with counter-weights to lift them. The trench was then back-filled, completing the process. The Big Inch pipeline had to pass under 33 rivers and 200 creeks and lakes, as well as under 289 railroad and 626 highway intersections. Specially lined tunnels were bored to lay the pipe under the roads and railroad lines, and specialist trenches dug to lay the pipelines across on the riverbeds and lakes, weighing down the pipeline to stop it floating to the surface. Around of underwater piping was laid in total. In marshy areas, the soft ground was filled in to provide firm foundations for the pipeline to rest on. The pumping stations for the pipelines were built on parcels of land between and in size;