Resumen
The paper is based on a project carried out to develop a new concept for the assessment of highway performance considering multi-modality, traffic management and ITS. Step by step a single-mode concept like it is used in the Austrian guidelines is extended to a multi-modal transport approach taking into account the capacity and quality of different modes on the road as well as in the corridor. By showing different options of meeting the quality target of road traffic this concept is aiming at a more efficient and cost effective use of traffic infrastructure and supporting the efficient allocation of limited funds. In order to allow for multi-modal considerations, transport demand has to be measured in persons and goods rather than in vehicle units. For the assessment of roads this combines the utilization of traffic capacity in terms of vehicles with the utilization of vehicle capacity in terms of occupancy and loading. So a multi-modal approach has to consider the characteristics and potentials of public transport on the road and of alternative means of transport in the corridor. The corridor comprises the road that has to be assessed as well as all parallel means of transport. The whole transport demand in passengers and goods using this corridor is taken into account. Corridor capacity results from the capacity of all means of transport. However, since the concept still focuses on the assessment of highway performance the transport contribution of the other means of transport is considered as reduction of the transport demand and hence of traffic load on the road. To finally assess the level of service on the road different criteria can be used. So the implications of using travel speed or reliability of travel time which is related to capacity utilization are discussed. Especially in hilly or mountainous regions a speed based assessment can result in problems due to unreasonable alignment and expensive road construction. Therefore the influences of different design parameters, horizontal alignment and grade as well as the traffic mix (proportions of heavy vehicles) on speed and capacity are analyzed in detail. The extended concept of road assessment is allowing multi-modal capacity utilization and capacity management to meet quality targets of road traffic. It supports the identification of different scenarios how transport demand can be accommodated adequately. It extends the range of suitable measures to respond to unsatisfactory quality of road traffic. Apart from road improvements it allows for management measures controlling a given demand rather than just accommodating it.