Abstract: This research reviews the types and causes of traffic congestion in relation to high volumes of vehicles on the roadway with particular reference to an unplanned city, Ado-Ekiti, Ekiti State, Nigeria. It examines the recurring and non-recurring congestion caused respectively by high volume of vehicles on the roadway during the same time periods and at critical locations and temporary disruption of transportation system like traffic incidents, poor weather etc. Also, the impacts that congestion delays have on the users are examined. The research then enumerates the measures that can be adopted to mitigate congestion in such traffic situations: these measures can be broadly classified into the supply initiatives like improvement of urban road network, coordination of traffic movements and the demand initiatives like road pricing, parking restrictions and entirely movements` reversals.