One for the open road

Open road tolling (ORT) or multi-lane free-flow (MLFF) tolling is the collection of toll fees by gantry-based electronic tolling and enforcement systems. Each vehicle is uniquely identified as it passes the charging point. The cheapest method for frequent user traffic is electronic identification via a transponder (tag). Video-based alternatives include pay-by-plate tolling (video tolling), where a vehicle's licence plate is used for account identification, and day pass. The technical and operational challenges associated with ORT are discussed: tracking vehicles in the multilane payment zone; coordination between subsystems (DSRC, classification and enforcement); maintaining system accuracy over random traffic patterns; avoiding systematic dodging; maximising the system availability; obtaining commercial interoperability; and the development of appropriate legislation. Tolling costs are dependent on non-tag transactions. The factors leading to maximum tag penetration rates are considered.