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Evaluate pros and cons of different methods for electronic toll collection.

The Washington State Department of Transportation’s experience with planning for tolling implementation.

Date Posted

Washington State Comprehensive Tolling Study: Final Report – Volume 2: Background Paper #8: Toll Technology Considerations, Opportunities, and Risks

Summary Information

The comprehensive tolling study conducted by Cambridge Systematics for the Washington State Department of Transportation (WSDOT) set out to provide recommendations to guide Washington as it develops toll facilities in the State. These policies emerged from background research and technical analysis.

The Washington State tolling study describes different types of electronic toll collection (ETC) methods, how they are applied to various toll facilities, note lessons learned from past experiences, and identifies the advantages and disadvantages of each. Furthermore, the study addresses institutional issues relating back office operations and enforcement processes.

Electronic toll collection (ETC) systems provide a simple solution for a statewide approach to tolling. Because ETC systems can reduce or eliminate the delays commonly associated with traditional toll roads, they have gained high acceptance rates among motorists. At the base of any ETC system is automatic vehicle identification (AVI), which can accurately identify a specific vehicle at highway speeds using in-vehicle transponders. A more sophisticated approach to ETC, that has been shown to be extremely reliable in collecting tolls while at the same time increasing throughput, is open road tolling (ORT). Agencies implementing ETC systems need to select technologies that fit within their budget but at the same time address their needs. These lessons have been developed based on current ETC practices around the world.

  • Implement automatic vehicle identification as a fast and reliable method to collect tolls. Automatic vehicle identification (AVI) involves the transmission of an identification code between a transponder in the vehicle and a roadside reader. The transponder is a radio frequency identification (RFID) two-way radio with a microprocessor, operating in the 900 MHz radio frequency band using dedicated short-range communication (DSRC) protocols. The transponder contains basic information, including an identification number, toll facility, vehicle type, etc. To complete tolling transactions, the roadside electronic readers emit radio frequencies via antennas to communicate with the transponders. For ETC, the vehicle identification number is linked to the customer's account from which the appropriate toll is automatically deducted or the customer is billed. Recently, policy considerations have suggested that lower-emissions vehicles should pay reduced tolls. The identification of such "green" vehicles can be accomplished through the use of AVI.
  • Increase throughput at tolling facilities by implementing open road tolling. Open road tolling (ORT) is the collection of tolls by purely electronic means. This is done through the installation of gantry-based electronic tolling and enforcement systems designed to enable unhindered passage of vehicles through the toll facility at normal highway speeds. ORT provides the technological approach to enabling the use of pricing for traffic management without requiring vehicles to stop and pay a toll. In most existing schemes, vehicles are identified via a transponder; vehicles without a transponder are identified by a video image of the license plate, which is then checked against a record of ETC account holders, or vehicles registered by drivers who have paid a toll over the telephone or Internet. License plates that cannot be reconciled to an account and have not registered are identified as violators and processed accordingly.

    ORT represents a significant technical jump compared to traditional tolling systems. From an operational point of view, the handling of violators and the control of the operational costs need to be carefully addressed. While using ORT can reduce costs associated with manual toll collection, the reduction in labor costs might be somewhat offset by the increase in need for image-based transactions and violation processing.
  • Examples of ORT implementations include:
    • SR 91 Express Lane in California USA, opened in 1995;
    • Westpark Tollway in Houston Texas, opened in 2004;
    • Highway 407 in Toronto Canada, opened in 1997;
    • Melbourne City Link in Australia, opened in 2000;
    • Cross Israel Highway, opened in mid 2002;
    • Autopista Central in Santiago Chile, opened at the end of 2004;
    • Costanera Norte in Santiago Chile, opened in April 2005;
    • Vespucio Sur in Santiago Chile, to be opened at the beginning of 2006; and
    • Vespucio Norte Express in Santiago Chile, to be opened at the beginning of 2006.
  • Maximize transponder usage. Costs associated with tolling operations are highly dependant on the level of non-transponder transactions (i.e., those processed using license plate images), as the processing costs of non-transponder transactions are significantly higher than for transponder transactions. Assuming that all vehicles are not required to be equipped with transponders, maximizing transponder usage depends in part on the following:
    • A successful marketing and public relations campaign that reaches all prospective customers and clearly explains the ETC, and/or ORT, system, its services, and its benefits;
    • Providing incentives to encourage transponder use, such as issuing tags free of charge, post-payment for toll charges incurred, and preferential rates for tag users; and
    • Limiting the number of times a customer can be charged by video tolling (to a maximum number of transactions per year, for example) without incurring additional fees.
  • Consider other approaches to identifying vehicles beyond traditional AVI methods. Agencies deploying ETC technologies need to consider the additional possibilities for vehicle identification beyond standard roadside readers. One approach is to install a global positioning system (GPS) in a vehicle to locate itself within a given charge area or network. The transponder would contain the appropriate charging structure, as well as information concerning when the vehicle should be charged. Charges are applied using the position information provided by the GPS system. The charge can either be deducted directly from a smart card located in the transponder or stored for later uploading and charging against the customers account or a bill can be sent to the customer. Charged corridors can be defined around specific zones in urban or rural areas where all vehicles (or specific categories) using the roadway will be subject to charges.
  • A second approach to vehicle identification involves the use of license plate readers (LPR) to capture an electronic image of a vehicle’s license plate. This information is used to charge the accounts of customers who have registered vehicles in advance. For vehicles that are not registered, the license plate number is used to determine the owner’s name and address so that an invoice for the toll and service fee can be sent. Some facilities allow infrequent users to register their vehicle for the day over the telephone or Internet to pay their toll, reducing the administrative cost of finding the owner and sending them an invoice. Highway 407 in Toronto, where there are no toll booths, uses a combination of transponders for regular customers and license plate readers for infrequent users to collect tolls.
  • Use Open Road Tolling (ORT) to manage traffic in heavily congested urban areas. To avoid the need for transponders, some systems, notably the London congestion charge scheme, use automatic number plate recognition (ANPR). ANPR uses a system of cameras to capture images of vehicles passing through tolled areas, and the image of the license plate is extracted and used to identify the vehicle. This allows customers to use the facility without any advance interaction with the toll agency. The disadvantage is that fully automatic recognition has a significant error rate, leading to billing errors. Conversely, systems that incorporate a manual review stage have much lower error rates, but require a continuing staffing expense.

Electronic toll collection provides a fast and efficient way for agencies to collect tolls, reducing fixed costs and increasing highway throughput. Essential to any ETC system is the use of AVI. There are a variety of different methods used for AVI including GPS, LPR, and ANPR, however the most widely implemented method is the use of roadside readers in conjunction with in-vehicle transponders. It is important for agencies implementing AVI to select the method that best fits within their budget while at the same time addresses their needs. To create the most fluid traffic conditions, agencies may wish to implement ORT alongside other traditional tolling methods. Because ETC systems can reduce or eliminate the delays commonly associated with traditional toll roads, they have gained high acceptance rates among motorists, and therefore will help address the ITS goals of mobility and customer satisfaction.