What limits the Effectiveness of the Road Congestion Scheme

-Price set too Low leads to a Limited Impact on Traffic Levels -Prices set too High lead to Little Cars being covered by the Charge. This can Decrease Trade for Firms within the Congestion Charge Area, Under-Utilisation of the Road, and cause Congestion in other Areas -May also Impact the Poorest in Society, and put them off using Cars in the Future