In the broad sense, " rolling resistance " includes wheel bearing resistance, energy loss by shaking both the roadbed ( and the earth underneath ) and the vehicle itself, and by sliding of the wheel, road / rail contact.
12.
Some modern systems, such as Bay Area Rapid Transit ( BART ) in San Francisco, use cylindrical wheels and flat-topped rails; BART is now switching to conical tread to reduce the noise caused by flange / rail contact and loss of adhesion of one of the wheels on curves.
