Open road tolling
Open road tolling (ORT), also called all-electronic tolling, cashless tolling, or free-flow tolling, is the collection of tolls on toll roads without the use of toll booths. An electronic toll collection system is usually used instead. The major advantage to ORT is that users are able to drive through the toll plaza at highway speeds without having to slow down to pay the toll. In some installations, ORT may also reduce congestion at the plazas by allowing more vehicles per hour/per lane. The disadvantage to ORT is that it relies on the honor system  to the extent that without the presence of toll booths there is typically no physical means of preventing drivers who have no intention of paying the toll from accessing the road. Toll operators refer to such toll evasion as "leakage." To deter such behavior, toll operators can employ tools such as high-definition cameras to identify violators, and leakage can be offset in part or whole by fees and fines collected against offenders. However, in many cases such enforcement is relatively limited (for example, targeting only commercial vehicles and other such flagrant and/or repeat offenders). Some toll operators prefer to  simply write off leakage as an expense, especially if the costs associated with collection efforts are expected to exceed the additional tolls, fees and/or fines that will likely be collected, or alternatively allow vehicles that are privately operated and/or below a specified size and/or weight to access the toll road free of charge. History. In 1959, Nobel Economics Prize winner William Vickrey was the first to propose a system of electronic tolling for the Washington metropolitan area. He proposed that each car would be equipped with a transponder. The transponder's personalized signal would be picked up when the car  passed through an intersection and then relayed to a central computer which would calculate the charge according to the intersection and the time of day and add it to the car's bill. Norway has been the world's pioneer in the widespread implementation of this technology. ETC was first introduced in Bergen, in 1986, operating together with traditional tollbooths. The first major deployment of an RFID electronic toll collection system in the United States was the TollTag system used on the Dallas North Tollway, implemented in 1989 by Amtech. The first fully automated toll highway in the world, Ontario  Highway 407, opened in Canada on 7 June 1997. The highway managed to achieve this automation through the use of both RFID technology and automatic number-plate recognition. In September 1998, Singapore became the first city in the world to implement an electronic road toll collection system for purposes of congestion pricing. Today there are many roads around the world working with electronic toll collection technologies, and ORT has opened the feasibility to implement congestion pricing policies in urban areas. Collection methods. Collection of tolls on open toll roads is usually conducted through either the use of transponders or automatic  plate recognition, the vast majority of which utilizes an overhead gantry system above the road. While rarely used as the primary vehicle identification method, automatic number plate recognition is used on a number of different highway systems. Both methods aims to eliminate the delay on toll roads by collecting tolls electronically by electronically debiting the accounts of registered car owners without requiring them to stop. Transponders. Transponders are a receiver-transmitter that will generate a reply signal upon proper electronic interrogation. Transponders are an adaptation of military identification friend or foe technology. Most current systems rely on radio-frequency identification , where an antenna at the toll gate communicates with a transponder on the vehicle via dedicated short-range communications (DSRC). Some early systems used barcodes affixed to each vehicle, to be read optically at the toll booth. Optical systems proved to have poor reading reliability, especially when faced with inclement weather and dirty vehicles. Automatic number plate recognition. Automatic number plate recognition (ANPR) or an automatic license plate reader (ALPR) is a system that uses optical character recognition on images to read the license plates on vehicles. While the technology is most commonly used by law enforcement for cataloging vehicle  movements and traffic enforcement, ANPR has also been used as a method of electronic toll collection. ANPR can be used in conjunction with transponder systems. If a transponder is not detected on a vehicle, a system of cameras located at each junction logs the vehicle's unique identity and an invoice is mailed. The use of ANPR reduces fraud related to cash transactions or non-payment, makes charging effective, and reduces the amount of required manpower to enforce the toll road, but requires expensive computer software. However, ANPR usage raises questions over privacy and data protection. ANPR allows police to  automatically compile vast databases of innocent road users' movements, thus invading their privacy. Another concern is that the collected data can be abused by employees or stolen by computer hackers. This has led the police of Scotland to delete their collection of ANPR records in 2016. As ANPR is a new technology, its use is often not tightly regulated; it is unclear whether ANPR in Scotland complied with the UK data retention laws. Highways using system. United States. The following is a list of some of the bridges and highways in the United States that use open road tolling: Open