The objective of this paper is to ease the planning of new toll projects by providing estimates of operating costs, and to help us make better informed decisions about the design of the toll collection system. To do so we use panel data for Norwegian toll companies to estimate average cost functions.The main results can be summarised as follows. We provide evidence of very important unexploited economies of scale. The estimates cost curves are very steep for traffic levels below the sample mean, and becomes almost entirely flat over a wide range above the sample mean. A higher share of vehicles using on board units will significantly reduce average costs. Competitive tendering will significantly reduce average operating costs by as much as 25 %. Our results also suggest that increased number of lanes, higher debt and passenger charging will increase average operating costs whereas average operating costs are lower for toll cordons compared with other projects.