Electronic licence plate technology: automatic vehicle location and identification A. T. BERGAN Transporrarion Cenrre, U n i v e r s i ~of Saskarchewan, Saskaroon, Sask., Canada S7N OW0

LOYDHENIONA N D MILANKRUKAR Planning Secrion, Oregon Deparrmenr of Transporrarion, Sale~n,OR 97310, U.S.A. AND

BRIANTAYLOR Can. J. Civ. Eng. Downloaded from www.nrcresearchpress.com by MICHIGAN STATE UNIV on 01/26/17 For personal use only.

Transporrarion Cenrre, Universio of Saskarchewan, Saskaroon, Sask., Canada S7N OW0

Received November 19, 1987 Revised manuscript accepted May 20, 1988 The purpose of this paper is to discuss the current level of technology in automatic vehicle identification (AVI). The technology is often referred to as electronic licence plate technology, due to the use of unique vehicle identity transponders (electronic licence plates) affixed to particular highway vehicles. Interrogator or roadside receiver units placed at strategic locations or nodes on a highway network can locate and identify the particular vehicle. The main thrust of the paper is on the different types of AVI systems and the technologies employed. The discussion includes the widespread applications for AVI from both a highway administrator and road transport industry point of view. Finally, the paper discusses two AVI demonstration projects. These projects are the urban system implemented in Hong Kong and the highway system in the United States and parts of Canada known as the Heavy Vehicle and Electronic Licence Plate Project (HELP). Key words: automatic vehicle identification, electronic licence plate, road pricing, automatic vehicle classification, weigh-inmotion, commercial transportation, vehicular traffic control, pavement, Heavy Truck and Electronic Licence Plate Project. L'objectif de cet article est de traiter de 1'Ctat actuel de la technologie dans le domaine de l'identification automatique des vkhicules (IAV). Cette technologie est souvent appelCe technologie de l'immatriculation Clectronique en raison de l'utilisation de transpondeurs d'identification de vChicule uniques (plaques d'irnrnatriculation Clectroniques) fixCs 2 certains vkhicules circulant sur les autoroutes. Des Cmetteurs-pilotes d'impulsions ou recepteurs placCs 2 des endroits ou branchements stratkgiques le long des routes peuvent repCrer et identifier un vChicule particulier. Cet article traite principalement des diffkrents types de syst5rnes IAV et des techniques employCes. La discussion porte sur les nombreuses applications de 1'IAV du point de vue de l'adrninistration des Ponts et ChaussCes et de l'industrie du transport. Finalement, il est question de deux projets de dkmonstration de I'IAV, soit le systkme urbain mis en oeuvre a Hong Kong et le systkme routier des Etats-Unis et d'une partie du Canada appelC le (< Heavy Vehicule and Electronic License Plate Project >> (HELP). Mors cle's : identification automatique des vkhicules, plaque d'immatriculation Clectronique, tarification des routes, classification automatique des vkhicules, pesage, transport commercial, contr6le de la circulation des vkhicules, chaussCe, HELP. [Traduit par la revue] Can. J. Civ. Eng. 15. 1035-1042 (1988)

1. Introduction and background Automatic vehicle identification (AVI) represents a major technological advance in the transportation industry. The extent of its potential applications are not yet fully explored, but the small projects undertaken to date are very promising and will undoubtedly lead to extensive use of the technology. The purpose of this paper is to explain this technology, some of its uses, and the progress of projects that have been established to test various systems. AVI as applied to road transportation systems had its origins in the railway industry. It was developed in response to a need within the railway industry to monitor the movement of trains; to enable efficient scheduling; and, more importantly, to reduce potential conflicts or collisions. Similarly, the application of AVI to the highway transportation industry allows a trucking firm or highway agency to locate and track individual vehicles (principally highway trucks) throughout a highway network. The use of AVI systems can give a highway agency the ability

NOTE:Written discussion of this paper is welcomed and will be received by the Editor until April 30, 1989 (address inside front cover). Printed in Canada / Imprime au Canada

to monitor dangerous goods movements, to ensure that specially permitted vehicles travel within the permit bounds, and to ensure compliance with set load limits. When combined with weigh in motion (WIM) systems and automatic vehicle classification (AVC) systems, data collection can be very comprehensive and used to accurately forecast and monitor traffic and loads. It has been shown that traditional design forecasting methods using short-term counts have generally underestimated the actual increase in truck traffic (Simms 1985). Recent studies using combined AVUWIM systems have indicated that "truck traffic weight and ESALs [equivalent standard axle loads] are increasing more rapidly than originally predicted ... Based on current ESALs this design life is 13.5 years [instead of 201, a reduction of 6.5 years or almost 33%" (Krukar 1986). This is very important from a highway planner's point of view as construction and maintenance scheduling and budgets are based on predicted ESALs being close to the actual. In other situations an AVI system can be and has been used to monitor and control traffic patterns within a road network (i.e., for reducing congestion within the central business district of a city) such as the system tested in Hong Kong. These systems

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RADIO AND

1

- Low power consumption

- suitable for remote

MAGNETlCl / INDUCTION 1 1 - Read only - Durable tags

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- Readlwrite capable

- Inexpensive transmitters and receivers (Existing ground loops can be tuned and used)

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/

- Small, compact tags - Line of sight operation

- Durable tags

- Future potential ( Semi-active tags)

FIG. 1. Current AVI technolc~ g ycommunication and tag types,

automatically invoice vehicle owners driving into the central business district (CBD) of a city and can be used to control traffic signals to optimize the flow of traffic.

2. AVI technology As previously stated, AVI systems for highway use are an outgrowth of the railway industry. Original railway identification systems utilized a barcode strip located on a locomotive, or car, and a railside optical barcode reader. In this system the unique identity number of the vehicle train (from the barcode) is read by the roadside reader when the train passes by. While the system worked reasonably well in the railway industry, it is less than ideal for the highway transportation industry. Barcodes when covered with mud and road spray are very difficult to read. Placing the barcode at a uniform height also becomes very difficult with the many different truck configurations operating. Modem AVI and railcar identification systems are based on technologies that are nonoptical, thus alleviating the abovementioned problems. 2 . l . System classes and operation The various AVI systems can be broken into classes, based on the technology used to transfer identification data. Each class offers unique advantages and can limit the extent of communication. In an application where only the vehicle identification is required, a read-only system is sufficient. In a readlwrite application, two-way communication between the data receiver and tag is possible. Readlwrite systems permit not only the transfer of the vehicle identification but also vehicle data (odometer readings and cargo data) and driver data (messages and possibly driver functions such as drowsiness by monitoring steering wheel movements). The differences in current AVI systems are a result of the many data communications methods that are available. The half-a-dozen companies in North America and Europe that have developed and marketed commercial AVI systems each use a slightly different system. The type of communications method to be used depends largely on the purpose of the AVI system, which in turn dictates the type of vehicle tag to be used. All modem AVI systems have two essential components: a vehicle-mounted identification module (tag) and a data receiv-

er. The receiver can be a roadside unit (commonly called an interrogator) or, in more elaborate systems, the receiver may be geo-synchronous satellites (telemetry systems). Communications methods can be broken into four general classes: radio, microwave, magnetic induction, and acoustic. Figure 1 presents a schematic of the various combinations of communication types, as well as the type of tag commonly used with each. It should be noted here that this list is by no means complete and that many variations on the different classes are possible. Radio and microwave systems communicate using tuned radio transmitters and receivers. A roadside interrogator or a geo-synchronous satellite can be used to receive the vehicle code. Telemetry systems offer the advantage of locating a vehicle anywhere within the satellite viewing window (or within the range of the tag). This is not as important for regular freight hauling as it is for emergency vehicles and for the tracking of dangerous goods. Roadside interrogators are much less expensive than satellites, but many may be required within a highway network to provide real-time location and identification. Magnetic induction systems convert data to phase-modulated pulses. The data in the pulses are transferred by inductive coupling from the tag to the interrogator via a ground loop. The ground loops used are the same as those used for traffic signal triggering. As a result they are inexpensive, with at least 10-year experience in installation and maintenance. Acoustic crystal systems are a very recent technology, which work on high-frequency sound waves. This technology is often referred to as surface acoustic wave (SAW). The vehicle tag consists of a lithium crystal which can be imbedded in the windshield (or any front portion) of the vehicle. A roadside interrogator excites this crystal with either a high-frequency sound wave or a low-power microwave. This wave is absorbed by the crystal, where it is modified with the vehicle code and retransmitted. The main drawback to this kind of system is that it works on line of site only, at a limited range (up to 10 m). An application exists, however, where a hand-held wand could be used to decode the tag (for use at toll facilities and parking lots). As mentioned, the type of communications system used to a large extent dictates the type of tag for the system. There are two general tag categories: passive and active. Passive tags have no on-vehicle power source. They obtain power from the roadside

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FIG.2. Active tag, radio AVI system operation. Time lapse 1 + 4: 1, vehicle approaches interrogator location, triggers sensing loop (tag continuously transmitting); 2, interrogator powers up, ready to receive; 3, interrogator receives code, stores or transfers data; and 4, interrogator transmits data to truck (if system equipped for readlwrite).

interrogator unit. This limits the communication method to microwave, inductance, or acoustic crystal, as only these methods can adequately energize the tag. With no internal power, the tags are used for read-only applications. As there are no replaceable power sources on passive tags, they are usually sealed units and tend to be very reliable. Active tags obtain their power from independent sources or the vehicle battery. These tags can be either read-only or readlwrite, where two-way communication between the tag and the interrogator is required. Having readlwrite capabilities is not without its drawbacks, however, as active tags tend to be less reliable than passive tags due to the battery requirement. Advances in low-power radio frequency (RF) transmitters have made possible semi-passive vehicle tags. These tags have a long-life battery sealed within the tag and afford the durability of a passive tag with readlwrite capabilities. Future AVI systems will utilize this technology to permit readlwrite capabilities at the price of current read-only systems. Figure 2 presents a radio-based AVI system using active tags. A roadside interrogator receives a vehicle identification code from a continuously transmitting tag. The interrogator may be set up to continuously scan for approaching tags or may be triggered to scan only when a vehicle passes over a sensing loop similar to the kind used in traffic signal control. The vehicle tag can be either read-only or readlwrite. One of the main advantages of radio communications is that radio transmitters are fairly low power, and the roadside interrogator unit may be set up as a battery-powered portable unit. Figure 3 presents a microwave-based AVI system using passive tags. When a vehicle passes by, the interrogator emits a low-power microwave signal. If the vehicle has a tag, the tag will be energized and will echo a presence signal. The interrogator will then transmit a high-power signal, which will fully energize the tag. The tag then transmits the vehicle identification code to the interrogator. The microwave-based system has one drawback in that the microwave transmitter requires a fairly large power supply to generate microwave signals. Large power supplies make microwave units impractical in remote locations. Figure 4 presents a magnetic induction AVI system using

passive tags. The ground loop is used to energize a passive tag on the vehicle. Energy is transferred to the tag via magnetic induction: once energized, the tag transmits its identification data. The data are received by either the inductive-sensing loop or by an antenna down-road of the energizing loop. Inductionbased AVI systems tend to be more suited to permanent installations due to the ground loops. The loops themselves are really no different than the loops used for traffic signal sensing, with the exception that they must be precision tuned. A variation on the magnetic inductance AVI system uses an active transponder that is signaled by an RF interrogator rather than the energized loops. This eliminates the need for precise tuning. The identification is then transmitted to either a sensing loop or an antenna down the road. Figure 5 presents an acoustic crystal AVI system using a passive tag imbedded in the vehicle windshield. When an approaching vehicle is in range, the interrogator transmits a high-frequency sound wave. This sound wave excites the tag, which modifies the incoming wave with the vehicle identification and then reflects the wave back to the interrogator. Figure 6 presents a telemetry-based AVI system using an active vehicle tag. In this case, a pair of satellite receivers can be used to locate an individual vehicle anywhere within their view range. The active tag must continuously broadcast its signal, or only broadcast at specific times, so that it can be located by the satellites. The main advantage of this system is the ability to locate an individual vehicle at any time and anywhere in the network. It should be noted that active tags may be used instead of passive tags for the systems presented in Figs. 3, 4, and 5 (microwave, magnetic inductance, or acoustic crystal). The use of these active tags is only practical where an existing read-only system can be upgraded to readlwrite. The reasoning is that microwave, inductance, and acoustic crystal-based systems are used to facilitate the use of passive tags in the first place. 2 . 2 . System costs and benefits There can be significant variations in the cost of an AVI system, depending on the technology employed and on the extent of implementation. Currently, vehicle tags railge from

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interrogator

FIG. 3. Passive tag, microwave AVI system operation. Time lapse 1 + 6: 1, vehicle approaches interrogator location, triggers sensing loop; 2 , interrogator sends a tag triggering signal (low power); 3, tag partially energized, echoes a presence signal; 4, interrogator transmits high-powered signal; 5, tag fully energized, transmits code; and 6, interrogator receives code, stores or transfers data.

I data stored I

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Enellzssion

1 I

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in on board

I memory

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1

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loops

FIG. 4. Passive tag, magnetic induction AVI system operation. Time lapse 1 + 3: 1 , vehicle approaches interrogator location, energizing loop energizes tag; 2, tag transfers data to sensing loop; and 3, interrogator receives code, stores or transfers data.

$100 to $500 per vehicle, and roadside interrogators cost from $5000 to $15 000 each. To fully realize the benefits of a system, a large number of vehicles need to be tagged, and many interrogator sites are required throughout the highway network. Consequently, an extensive system can be costly. Direct monetary benefits for AVI are difficult to identify in a general sense. The benefits can be broken into three general categories: (1) agency savings associated with labour reduction at entry points and toll facilities, (2) trucking firm savings associated with the real-time location and identification of haul units, and (3) agency benefits associated with enhanced vehicle movement data. It should be noted that included in trucking firm benefits of item (2) above is the potential reduction in theft. It has been estimated that annual losses to the trucking industry through theft in the U. S . approximate to $7 billion (Henion and Koos 1986). This benefit alone provides an attractive enough return to justify an AVI system.

2.3. Other potential technologies There is another promising vehicle identification technology that is currently under development and deserves mention. The system is called digital imaging processing and operates on the basis of optical text or number recognition. The system consists of a roadside digital image camera (similar to a video camera), lighting units: and the associated computer hardware and software to read or recognize the numbers on the licence plate. As a vehicle passes by, the camera records the digital image of its licence plate. ~ f t e reading r (or recognizing) the characters making up the licence plate number, the data is relayed to a central computer by modem or telephone to allow vehicle identification. The system inevitablv suffers when licence plates are not located in the same place on individual vehicles, when the licence plates get dirty, or when atmospheric visibility is poor. While digital imaging technology is still in its infancy, there

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transmission

data stored in on-board

1

I modem transmission

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INTERROGATOR

FIG. 5 . Passive tag, acoustic crystal AVI system operation. Time lapse 1+ 3: 1, vehicle approaches interrogator location, acoustic signal sent by interrogator energizes crystal; 2, tag echoes code to interrogator; and 3, interrogator receives code, stores or transfers data.

FIG. 6. Active tag, telemetry AVI system operation. Time lapse I + 3: 1, vehicle travelling down roadway, tag continuously transmitting; 2, location and identification of vehicle received by two satellites; and 3, satellites relay identification data to ground station, location of vehicle calculated.

is one major benefit of its potential use in that there is no need for the vehicle to be identified as having a transponder on board. This is important due to opposition by a few trucking firms with regards to the use and cost of vehicle transponders. 2.4. Compatibility and flexibility As mentioned previously, half-a-dozen companies manufacture and market AVI systems in North America and Europe. Due to the competitivk nature of these companies and ihe present rate of change of technology, there are a wide variety of tag, interrogator, and communications methods. This has generally caused noncompatibility between the various AVI systems. Presently, most of the existing AVI systems have been set up as feasibility or demonstration projects, with no need (or incentive) for compatibility between the variety of equipment used. Even though the equipment from different manufacturers is noncompatible, the data obtained from the systems can be made compatible. Almost all of the AVI systems utilize digital computers to control the system, and the data transmission between the tag and the interrogator is usually digitally based. In recent years, data handling has become quite standardized. The

transformation of data from the format of one computer system to another system is not usually difficult. The use of computers to control an AVI system allows much flexibility within the system. Since the control of a system will depend largely on software, which is easy to change,-the layout of the triggering and interrogator hardware can be such that it will match the conditions at most sites.

3. Potential applications The potential applications for AVI are varied, offering potential benefits for both highway agencies and the trucking industry. A partial list of these applications include offering highway agencies a complete user information system, traffic control enhancement, fleet management, tracking special purpose vehicles (including vehicles hauling dangerous goods), resource movement monitoring, and national security (Koos 1986). Following are detailed descriptions of these applications. 3.1. Complete information system The efficient planning, design, and operation of a highway system requires accurate weight and traffic data. Ideally, the collection of these data should be inexpensive, timely, and safe.

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Traditionally, traffic data in Canada and the United States have been obtained from continuous axle counts at select locations throughout the highway network. The breakdown of vehicle classifications is achieved by performing 8-, 12-, and 24-h manual classifications. Truck weight studies are typically performed during summer daylight hours. Since manual counts are highly labour-intensive (due to the associated paper work) and restricted to certain periods of the year and day, this method is neither timely nor inexpensive. An AVI system could be used to significantly reduce the paper work associated with collection and enforcement. There is evidence to suggest that the collected data may not accurately reflect the actual truck traffic volume or weights and, subsequently, the equivalent single axle Ioads (ESALs). Independent studies (Krukar 1986; Simms 1985) report that while traffic classification counts are usually taken during daylight hours, truck traffic peaks are variable, often occurring around 4 a.m. Since current pavement design-life methods use ESALs as a basis, these unforeseen trends and subsequent underestimates in ESALs can cause a significant decrease in pavement life, compared to the design life. The specific role of AVI in data collection, for an agency, is not in the actual collection of weight data but in the product of distance and weight (t.km). With AVI devices an agency can know exactly how many ESALs a roadway was subjected to and who applied them. This is a powerful incentive for truckers to remain within load limits and would eliminate unfair competition between trucking firms, as some trucking firms habitually overload their trucks. The ability for an agency to collect accurate data on heavy truck traffic (weight and volume) will allow that agency to monitor the loading that a pavement has undergone, and to take preventive measures in the event that the predicted design is being exceeded. These measures could include decreasing the time between overlays and generally rethinking future design alternatives.

3.2. Traffic controllflow enhancement Modern traffic control and signal systems rely on real-time traffic monitoring to allow maximum efficiency within the system. An AVI system can be utilized to obtain this real-time data. Note though, that to be effective, a significant number of vehicles within the system must be equipped with tags. In this way, an accurate representation of the traffic flow can be gained from the sensing of only tagged vehicles. Such systems are currently in use in LeMans, France (Vapor Corporation 1985). Signal systems can be set up so that priority is given to emergency vehicles (police, fire, and ambulance) as well as to public transit vehicles. A similar application exists for automatic charging of AVI-equipped vehicles at toll facilities and for access to parking facilities. 3.3. Fleet management AVI offers a variety of benefits for freight and passenger transport companies. These benefits include real-time scheduling and routing; vehicle control within loading, warehouse, and terminal facilities; and tracking of vehicles within the highway network. An AVI installation in Lyon, France (Vapor Corporation 1985) is currently used to control busses at a major passenger service terminal. Information on arrivals, departures, and gate data is quickly relayed to overhead information boards. Busses are guided through the terminal upon their arrival and identification.

3.4. Tracking of special-purpose vehicles Enforcement agencies can realize benefits of an AVI system rm~t with the ability to monitor the movement of ~ ~ e c i a l - ~ e and dangerous-goods-handling vehicles. These special-permit vehicles include overweight, oversize, and special-hour vehicles. 3.5. Resource itldustrv AVI applications in the resource industry include the monitoring of the time and number of loads for both highway and off-highway trucks. In this respect, an AVI systems operates as a stockpile or reserve monitor, in a labour-saving capacity. 3.6. National security An AVI system will give an enforcement agency the ability to speed up border crossings for tagged vehicles, to track foreign vehicles within the highway network (to prevent smuggling and "hot" loads). and to track stolen vehicles in the svstem. It should be noted that this is of prime importance to large trucking firms who occasionally lose trailers to theft. ,,

4. Review of existing AVI systems 4.1. The Hong Kong experience Like many other cities in the world, Hong Kong has faced major traffic congestion problems. Its urban core is the most densely populated place in the world with 4 million people living in an area of 40 k2 (100 000 personslkm2) surrounding the harbour. This population density along with rising vehicle ownership rates and coupled with minimal opportunity for providing more capacity has created severe traffic management problems. In 1982, the Government of Hong Kong, recognizing the imminent crisis, took measures to decrease traffic congestion. These were (1) to double registration fees for automobiles imported into Hong Kong and to treble yearly licence fees and (2) to increase the gasoline tax by $O.lO/L. Research into a long-range solution - that of electronic road pricing - was also initiated. While the first two solutions were successful in reducing car registrations, they did little to solve the traffic problem in the central business district (CBD). These extra taxes had the largest effect on the poorer people living on the outskirts of the city while the more affluent people living near the CBD still registered and drove their vehicles. The only option left as seen by the Hong Kong government was electronic road pricing. The objectives of the road pricing scheme were (1) to reduce congestion in the CBD, especially during the peak hours; (2) to correct the problem of inequality in automobile registration and licensing fees imposed earlier; and (3) to set up an equitable road user tax so that users pay for the amount and timing of the actual infrastructure they use. In 1983 the Government of Hong Kong decided to undertake an experiment to test an AVI system. A sample of 2600 vehicles and 18 identification locations surrounding the CBD were used in the 2-year, $5 million (U.S.) experiment. The full-scale system was to involve 100-200 interrogator locations on roads leading into the CBD; electronic signs indicating tolls to motorists; and a transponder affixed to every registered vehicle in Hong Kong. The experimental system consisted of transponders attached to the vehicles, sensing induction loops buried in the roadway, roadside computers attached to the induction loops, and a telephone link from the roadside computer to a main computer. During the 2-year experiment the consultant found that -

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99.7% of the cars passing the interrogators were identified correctly and that the computers were working 99% of the time regardless of weather. A backup system consisting of closed circuit TV cameras was used to identify vehicles when an erroneous or no signal was recorded. Sample driver invoices were produced in a variety of formats, some as detailed as listing the time and place that the charge was registered. While the system seemed to be technically feasible, and the results of the experiment were very good, a major obstacle was still blocking the road to full implementation. The system had to be approved through political channels. Owing to the political climate at the time and the nature of Hong Kong's free enterprise system, two very polarized factions developed on either side of the AV1 issue. The Hong Kong Automobile Association felt that the congestion problem was exaggerated by the government and that the technology was not tested enough and likely to fail. Others felt the system would constitute an invasion of privacy. There was also a general distrust of the government's assurances that the overall taxation rates would not be affected and that the information gathered would be kept in the strictest of confidence. The government of Hong Kong, on the other hand, felt that the demonstration project was very successful and that the system should be implemented on the basis of efficiency and cost savings associated with labour reduction for enforcement. As a result of the political climate and the vocal minority, road pricing was not implemented on a full-scale basis. Instead, it was made optional to vehicle owners who could then drive through the Lion Rock Tunnel without stopping to pay a toll, thereby reducing congestion and increasing the speed of passage for the commuter. The results of the Hong Kong experience are very interesting in that it is the first such system to be attempted on a large scale. The first conclusion that can be drawn from the results is that a full-scale AVI system is technically feasible. The application of AVI to road pricing is politically sensitive though, and must be approached very carefully by an agency (Borins 1986). Undoubtedly the system will be viewed negatively as an extra tax. The second conclusion is that the system does present some real opportunities in reducing congestion on toll routes by speeding traffic flow with automatic billing and in driver information systems where drivers are alerted to congestion problems by electronic signs alongside a roadway. Whether or not AV1 would substantially reduce congestion in the CBD is still unknown because the full-scale system has not yet been implemented. 4.2. The HELP project A number of trends have become evident: data collection is becoming more and more expensive, law enforcement is becoming more difficult, and congestion at ports of entry and toll stations is increasing. It was in response to difficulties such as these that studies have been undertaken to determine the feasibility of AVI implementation in a large-scale way. The most notable of these studies in terms of scale is the HELP (heavy vehicle electronic licence plate) project. The HELP project evolved out of a concept paper done to improve the efficiency of Arizona's ports of entry. There was a great deal of support for such a project at both state and national levels; in fact, the Federal Highway Administration (FHWA) was so interested that in 1984 they gave a grant to Arizona to do a technical feasibility study on implementing a multi-state

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demonstration project. At much the same time the State of Oregon undertook a proof of concept demonstration project called the Oregon Weigh-in-Motion and AV1 Demonstration Project. The results of these two studies showed promise of very quick payback for full-scale implementation and potential benefits both to the trucker and to the government (Reed and Schmitt 1985). In February 1985, a meeting of trucking and government representatives was held to assess the possibility of a multi-state project. Through this meeting a multi-state association was formed and a project dubbed the "Crescent Study" was undertaken (it was later changed to HELP). The objectives of the HELP project, as set out, were to undertake cooperative research to investigate new tools available to gather heavy truck data, to determine functional and practical applications for automated data collection systems, and to determine whether a national system of AVI would be cost-effective (Henion and Koos 1986). To accomplish these objectives a number of contracts have been let. These involve testing various classes of AV1 transponders and interrogators, designing system software, studying potential applications for industry, studying the feasibility of a satellite-based traffic monitoring system, and finally, undertaking the actual deployment and administration for the AVI system (Henion and Koos 1986). The project will consist of AVI sites along interstate highways 1-5 and 1-10. Approximately 5000 vehicles from 200 trucking companies will be involved. The cost of the project is estimated to be $6 million. Preliminary cost-benefit analysis of this project indicates benefit to cost ratios of 4 to 5 when benefits to both the highway agencies and the trucking firms are considered. This is based on estimated system capital costs of $12 million and benefits of $20 million per year for highway agencies and $40 million per year for trucking firms (Reed and Schmitt 1985). The timetable for the project calls for testing of equipment for the demonstration project to have been completed by the end of 1987. By then the actual demonstration project should be started and data collection underway. The demonstration project should be complete in early 1990, and the final evaluation and report finished within 3 months (Reed and Schmitt 1985; Henion and Koos 1986).

5. Conclusion The implementation of accurate, dependable AV1 systems is currently possible. Current research can be expected to further enhance AVI performance. Systems based on the discussed technologies are being implemented in various demonstration projects. Reviews of the system performance should be available in the next couple of years to verify the technology. It is highly probable that full-scale implementation of AV1 systems will be seen in the next 3 to 5 years. The use of AVI systems has the potential to provide significant monetary savings. Interestingly, the benefits to the trucking industry appear to exceed potential benefits to the highway agencies. It would appear that the political attitude portrayed during the presentation or feasibility portion of system implementation can seriously affect the way the system is perceived by the public, particularly by the trucking firms. The benefits associated with the reduction in theft, and subsequent reduction in insurance premiums, for trucking agencies far outweighs opposition to AVI on the grounds that

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government is promoting AVI to monitor and further regulate heavy vehicles. BORINS, S. F. 1986. The political economy of road pricing: the case of Hong Kong. Proceedings, Research for Tomorrow's Transport Requirements at the World Conference on Transportation Research, Vancouver, B.C., pp. 1373-1376. HENION, L., and Koos, B. 1986. Technology and the HELP program -potential uses for government and industry. International Conference on the Roles of Private Enterprise and Market Processes in the Financing and Provision of Roads, Baltimore, MD, p. 67. Koos, B. 1986. AVI benefits for states. Oregon State Highway Division, Planning Section, Salem, OR, p. 23.

KRUKAR, M. 1986. Final report, weigh in motion and AVI demonstration program. The Oregon Department of Transportation, Salem, OR, p. 99. L. A. 1985. Heavy vehicle electronic REED,H. A,, and SCHMITT, license plate project and the crescent demonstration project. Proceedings, Second National Weigh-in-Motion Conference, Atlanta, GA, p. 45. SIMMS, P. 1985. The use of weigh-in-motion systems to collect design data. Paper presented to The National Conference on Weigh in Motion, Technology and Applications, Atlanta, GA, p. 24. VAPORCORPORATION. 1985. General description of VETAG systems. Vapor Bulletin No. 100, Chicago, IL.