| I was just in time to catch 3 GGXR locomotives winding their train out of Mac Yard. Note the very rare SD45T-2 trailing locomotive. The term tunnel motors was a nickname describing the SD45T-2 and later SD40T-2 built during a nearly ten-year period starting in the early 1970s. The idea began as a test by Electro-Motive and Southern Pacific to solve an overheating issue. Engineers from both companies tried several different ideas to reduce, and hopefully eliminate locomotives from overheating inside the long tunnels and snowsheds found along the Southern Pacific's main line in the Sierra Nevada Mountains of California and Nevada. Ultimately, they determined that by merely moving the air-intakes near the bottom of the carbody to draw in cooler air would solve the issue and the idea proved successful. Later, Rio Grande used the same concept on a large order of SD40T-2s, which was also purchased by SP. Today, many of these units remain in service on various shortlines and regionals |