The factors contributing to the line haul transportation costs of very large trucks operating on the Ontario highway system are calculated from fundamental tractive resistance equations and tractive effort characteristics for two "weigh-out" commodity types and representative haul routes. These calculated costs are compared with some observed costs and earlier analyses to check the validity of the models. The theoretical models are then used to assess the impact on operating costs of a variety of truck parameters which include truck type and tire pressures. The pavement damage created by the different truck types are estimated and the damage costs compared with the savings in line haul transportation costs. It is concluded that the pavement damage impacts of different truck types should be carefully compared with potential line haul transportation cost savings to ensure that allowable truck configurations are economically efficient with respect to both public and private costs.Key words: highway engineering, pavement damage, pavement cost, truck operating cost, vehicle weights.