A general review of the socio-economic impact of the intelligent transport system (ITS) is presented with a case study to demonstrate the data envelopment analysis method. Cost-benefit analyses are still the dominant method for evaluating ITS and other transport engineering projects, while cost effective analyses and multi-criteria appraisals are widely used to define and prioritize objectives by providing useful information for the most promising policy decisions. Both cost-benefit analyses and a data envelopment analysis method are applied to analyze the socio-economic impact of convoy driving systems. The main findings are that a convoy provides a worthwhile benefit-cost ratio when more than 30% of the traffics in the convoys and the traffic load exceeds 5500 vehicles/h for a three-lane motorway. The results also show that for a fixed percentage of convoys, increased demand will increase the data envelopment analysis method relative efficiency and that the neglect of certain output indicators of an ITS may result in underestimation of the system effects.