tranquilice SG Public buses and emergency vehicles (plus others maybe) do not need to pay ERP charges. Note that the IU on these vehicles are red in colour which is different from those in other vehicles. I guess why IU are installed on all vehicles is for the system to keep track on the total number of vehicles that pass thru a gantry.
tranquilice SG All vehicles (including foreign registered) are required to be fitted with a IU. Scheduled buses (ie. SBST, Tibs, CSS), police vehicles and emergency vehicles (eg. fire engines, ambulances) are exempted from the ERP.
Yusry SG Actually, the CC does not need to be in. But it is advised to have one in so that administrative work is reduced. The dumb ERP system was programmed for the need for a cashcard to be in the IU all the time. Anyway, during my time in NS, we never bothered to put in any CC in the IU.