During that year, Tesla worked in Pittsburgh, helping to create an alternating current system to power the city's streetcars. He found the time there frustrating because of conflicts between him and the other Westinghouse engineers over how best to implement AC power. Between them, they settled on a 60-cycle AC current system Tesla proposed (to match the working frequency of Tesla's motor), although they soon found that, since Tesla's induction motor could only run at a constant speed, it would not work for street cars. They ended up using a DC traction motor instead.
What ended up being used for the streetcars in the place of Tesla's system?
a DC traction motor a DC traction motor DC traction motor