This report describes the work that has been undertaken to establish the business case for Controlled Motorways. Since the introduction of the Controlled Motorways on the M25 in 1995, the Highways Agency (HA) has commissioned a number of studies to optimise system performance and to quantify the impact of the system with the aim of establishing the business case for implementation and developing guidelines for future roll-out. The scope of this particular document is to provide a summary of the work undertaken and the key results from the various Controlled Motorways studies.