(The following appeared on the Hampton Roads Inside Business Journal on May 13, 2011.)
ROANOKE, Va. — To keep pace with surging freight shipments, Norfolk Southern has ordered 1,500 specially designed coal cars and 242 AC locomotives.
AC locomotives?
“Locomotives are powered by diesel engines that generate electricity for the traction motors that turn the wheels,” said Robin Chapman, Norfolk Southern spokesman, in an email. “The generators produce either direct current (DC) or alternating current (AC).
“Most locomotives in our fleet are DC,” he said. “There are operating and maintenance cost advantages of AC over DC, but AC units are costlier to manufacture.
“For us, the chief advantage of AC locomotives is their ability to produce high tractive effort at low speeds, and so they are well suited for hauling heavy coal trains up mountains. At higher speeds, the advantages diminish.”
Full story: Hampton Roads Inside Business Journal