A key element of the plan was a new dam and reservoir in the Hetch Hetchy Valley, but access to the area was poor, so a railroad was planned to help build the dam. The steep terrain dictated a 4-degree roadbed, roughly twice as steep as a "regular" railroad. The steep grades dictated geared-down locomotives. The first of the Hetch Hetchy Railroad (HHRR) were completed in 1915, and the remaining were completed by October 1917. Construction costs for the HHRR were about US$3 million, far less than what the city might have paid contractors to transport workers, concrete and other materials for the dam over the rough and steep terrain by 12 mule train wagons. The president of the railroad was San Francisco Mayor James Rolph, and the vice president and general manager was the construction project's chief engineer Michael O'Shaughnessy. The Hetch Hetchy Railroad was begun as a connection of the Sierra Railway at Hetch Hetchy Junction, west of Jamestown, and extended another to the Hetch Hetchy Dam (later named the O'Shaughnessy Dam after the chief engineer) site for delivery of construction workers and materials. The regular trains were supplemented by trucks converted to run on the tracks to carry unscheduled loads of men or supplies or evacuate ambulance patients. The railroad was dismantled and part of its road bed converted into a highway after the Michael O'Shaughnessy dam was completed, and the new Don Pedro Reservoir built in 1971 flooded part of the original track line.