Road Equivalent Tariff (RET) involves setting ferry fares on the basis of the cost of traveling an equivalent distance by road, including a fixed element to keep fares sustainable and cover fixed costs such as infrastructure. Transport Scotland commissioned a two-year evaluation of the impact of RET on the island of Arran. The evaluation was informed by a range of primary (i.e. ferry user, household, business and haulier surveys) and secondary (i.e. ferry operator and socio-economic data) research.