With a wave of consolidation behind it, North American railroading is once again a good business to be in. Freight traffic is booming. Locomotive orders are coming in at a record pace from the Big Six roads that dominate rail transportation on the continent: Union Pacific, BNSF, CSX, Norfolk Southern, Canadian National, and Canadian Pacific. And the two remaining diesel builders, EMD and GE, are locked in a battle to become the locomotive supplier for the 21st century.

The standard bearers for EMD, newly independent and no longer a division of General Motors, are its 70 Series road freight engines, the SD70M-2 shown here and the SD70ACe detailed on page 8. Both locomotives are powered by a two-cycle, 16-cylinder, 4300-horsepower model 710 prime mover and have a top speed of 70 mph. The biggest difference between the siblings is what’s under the floor: traditional DC traction motors in the SD70M-2’s trucks and AC traction motors in the SD70ACe. While AC traction motors put more tractive effort on the rails and enable an SD70ACe to start a heavier train with the same horsepower, that additional capability comes at a cost. AC-powered locomotives are both more expensive and more electrically complex than engines with DC traction motors, which most diesels have used since the 1940s. For that reason, the Norfolk Southern and Canadian National have found the SD70M-2 more suitable to their needs, and both roads roster large DC fleets. Regional railroad Florida East Coast has been another DC-power advocate.

Did You Know?

Fully loaded, a 70 Series locomotive carries 4,900 gallons of diesel fuel, 420 gallons of lube oil, and 275 gallons of cooling water.