In stationary traffic do you hear the electric cooling fan for the radiator run?
Does it over heat in normally moving traffic?
Is the coolant boiling?
Or is the temperature gauge going right up high into the red zone?
Is the cooling fan working? They can suffer from duff bushings and can seize! Any head gasket problems? Connections on temperature sensor in head? A bit more info may help!!
Aye, short on information. How long is a piece of string. Could be a number of things ranging from low coolant level to something more severe. A bit more investigation & what's going on would help.