Electronic toll collection

Electronic toll collection

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Electronic toll collection field performance evaluations
Pietrzyk, Michael C
University of South Florida -- Center for Urban Transportation Research
Florida -- Dept. of Transportation
Place of Publication:
Florida Dept. of Transportation
Publication Date:
Physical Description:
44 p. : ill. ; 28 cm.


Subjects / Keywords:
Toll roads -- Evaluation -- Florida ( lcsh )
Tolls -- Florida ( lcsh )
government publication (state, provincial, terriorial, dependent) ( marcgt )
non-fiction ( marcgt )


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Also available online.
General Note:
"June, 1993."
General Note:
Prepared by the Center for Urban Transportation Research, College of Engineering, University of South Florida for Florida Department of Transportation.
General Note:
Principal investigator's name from t.p. verso.
Statement of Responsibility:
[Michael Pietrzyk, principal investigator].

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University of South Florida Library
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University of South Florida
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All applicable rights reserved by the source institution and holding location.
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028432472 ( ALEPH )
29981522 ( OCLC )
C01-00392 ( USFLDC DOI )
c1.392 ( USFLDC Handle )
388.114 ( ddc )

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Pietrzyk, Michael C.
Electronic toll collection :
field performance evaluations /
[Michael Pietrzyk, principal investigator].
[Tallahassee?] :
Florida Dept. of Transportation,
44 p. :
ill. ;
28 cm.
"June, 1993."
Prepared by the Center for Urban Transportation Research, College of Engineering, University of South Florida for Florida Department of Transportation.
Principal investigator's name from t.p. verso.
Also available online.
Toll roads
z Florida
x Evaluation.
University of South Florida.
Center for Urban Transportation Research.
Dept. of Transportation.
t Center for Urban Transportation Research Publications [USF].
u http://digital.lib.usf.edu/?c1.392


ELECTRONIC TOLL COLLECTION: FIELD PERFORMANCE EVALUATIONS Florida Department of Transportation ReprotbtctiOII by permission only prepared by Center for Urban Transportation Research College of Engineering University of South Florida June 1993


2 ACKNOWLEDGMENTS The Center for Urban T ransportation Research (CUTR) would like to recognize and acknowledge several key individuals for their assistance and contribution to this evaluation project and report. Chester Chandler served as project manager for the Florida Department of Transportation (FOOT) Florida's Turnpike Office, Bruce Seiler (FOOT Turnpike Operations & Maiotenanee) and Rick Nelson (FDOTToll Operations) afforded the Sunrise Mainline Plaza on the Sawgrass Expressway to CUTR, Tom Knuckey and Armando Amel (Post, Buckley, Schuh & Jernigan, Inc. ) provided field coordination, Jeanie Banyas (Administrative Management Consultants, Inc. ) arranged for the evalua tion fleet vehicles and drivers AI Palmer (Palmer & Associates, Inc.) provided technical insight and guidance L t T erry Davis (Florida Highway Patrol) provided patrolmen throughout evaluation periods to assist in traffic maintenance plan, and Jeff Nesbit (Sverdrup Corporation) secured all eva l uation site needs for CUTR and theparticipants. CUTR would also like to thaok Jim Ely (FOOT Turnpike Director) and Christine Speer (FOOT Toll Operations Director) for their assistance and guidance in this effort Principal investigator for this evaluation and report was Michael Pietrzyk, Senior Research Associate and IVHS Program Mana ger at CUTR. Evaluation, analysis, and report preparation assistance and review was provided by Dr. Larry Dunleavy (USF Eiectrical E ngineering) and Dr. Lee Weaver (USF-lndustrial & Management Systems Engineering). Undergraduate and graduate student assistance during field evaluations and report preparation was provided by Mike Neidhart Joe Hagge, Ray Yettaw, Greg Kasson, Amos Ehoud, Mike Zimmerman, Tony Rodriguez, April Gurba, and Joey Duval. Report preparation design and layout can be attrib uted to Terri Oates CUTR P rogram Assistant. The coordination and successful completion of this p r oject can be attributed to the aforementioned individuals. Their assistance and dedication to this effort bas been gratefully appreciated.


3 TABLE OF CONTENTS GLOSSARY OF TERMS ..... .. ....... .. . ................... .... .. . ... 5 I. EXECUTIVE SUMMARY .. ...... .. ...................... .. ................. II II. PURPOSE AND SCOPE .......................... .. .......................... 12 III. BACKGROUND .................... .... ........................................... 13 IV EVALUA'flONPROTOCOLAND ..................................... 15 CONFIGURATION PLAN A. Other ETC Field Perfo)'1)1. ancc Evaluations ....... .......... .... ......................................... 15 B. FOOT Eva l uation Parameters ..................................... 15 C. FOOT Eva l uatio n Plan ............................................... 20 V. EVALUATION FINDINGS ....................................... ... ..... .. 21 A.General Operation of ETC System s .... ..................................... ..... .... .. ........ ... .. ..... 2 1 B Operating Chara c teristics of Participants ................... .... .......................................... 26 C. General Test Plan for Ele c tri c al Field Meas u rements ................. .. .. ............................... 31 D. Summary of Evaluation Fiodings ....................... .... ................................ .......... 33 VI. OTHER EVALUATION ISS U ES ...... .. ............................... 37 A. Hea l th and Perfom1ance F a c t ors ..... .................................................................. 37 B. Recommen d ations for Further Evaluat ion .............. .............. .................................. .. 43 VII. CONCLUSIONS ................... ..... ..................... ................ .. 4 3


5 GLOSSARY OF TERMS Active system = utilizes a trausponder which takes its power from the vehicle itself. Analog VES system =never converts photo images to d i gital form, but stores image on video tape for manual extraction at a la te r time (i.e ., no provision for automatic extraction of images). Anomalies = something different, abnormal, peculiar, or not easily classified. For purposes of this evaluation, anomaly categories were classified as: (1) excluded (procedural/set-up problem, cor rect ed problem, inconsistent conditions), (2) invalid transactions, (3) missing or bad photos, and (4) incorrect pho tos. ANSI = American National Standards Insti tute Antenna beam width = generally interpreted as the 3dB beam width, or the space where power radiated from the aote. nna is within 3dB (or a factor of0.5) of its maximum value. Anti-passbaek m an evaluation typically perforrned during optional evaluations, whe re vehicles enter/leave the field of interrogation in the toll lane in short periods of lime to deterrnine the number of separate transactions that occur for a particular vehicle. ASK = (amplitude shift keying) a modu l ation technique in whi ch the carrier wave is keyed on and off by the binary data signal. A VI= (automatic vehicle identi fication) transponder bas ed systems which monitor passage of vehicles passed fixed sensors to capture such information as time, location, and unique identi fication data. Backscatter = electromagnetic field reflected from objects in the field of view of a traosmittiog antenna. BCS = block check sequence. Bit = a unit of computer information, a binary digit, equivalent to the result o f a choi c e b etw een two alternatives (as "yes or "no", "on or "off'), physically represented by an electrical pulse or magne tized spot. Sixteen bits equal 1 word. Bit (data transmission) rate = the number of bits transmitted in a given second. Byte = a group of adjacent binary digits (8 bits=! byte) that a comput e r processes as a unit. CENTER = (center frequency) the frequency at the center of the spectrum analyzer display or plot. Checksum = a code at the end of a frame that tells exactly how many bytes were transmitted.


6 "Core Battery" evaluations= those evaluations occurring on Tuesdays and Wednesdays, that were mandatory for all participants. A total of 1,214 separate vehicle passages constituted these evaluations, including evaluations of the YES subsystem. CRC =(cycli c redundancy checking) an error control method which invo lves the add ition of a block check sequence (BCS) of bits to the data message The whole data stream (message plus BCS) should obtain a zero r e maind er if no error has occurred. CW = continuous wave. dbm icrovolt= (decibel) twenty times the logarithm oftl1e signal voltage referenced to o .ne mic. ro volt. For example A db-microvolts is equal to 20 Log (A (volts)/0.000001 volts). Digital VES system = capable of immediately converting images into digital form for storage an d/or re trieval. Digitizing oscilloscope an e l ectronic instrument capabl e o f d isplaying a d i gitized (or broke n into discrete values) version of an input signal (y-axis) versus time (x-axis). Director= a director is a half wavelength dipole which receives energy radiated from t h e antenna and then re-directs it i n the desired direction. DSR digital shift register. EMF= electro-magnetic fields. EMI magnetic int e rference. ETC= (electronic toll collection) advanced toll collection systems using transponders and telecom munications devices s uch as A VI. ETC provides for increased t oll lane throughput with non-stop toll tran s actions in both r ead and r ead/write SYstems. ETTM = (electronic toll and traffic management ) expands on basic A VI or ETC by utilizing two way communication between vehicl es and roadside to provide a full range of traffic and fleet man agement, safety and incident management, and toll management functions. FCC =Federal Communications Commission Frame = a time interval containing a complete singl e lane cycle. Frame rate= the ra te at which frames are repeated 011 a single lane. FSK =(frequ ency shift keying) a d igital modulation technique where the frequency is changed between two discrete values eac h generated by a separate oscillator embedded in t h e tra n sponder.


GHz = (gigahertz) a measure offrequency (I billion cycles per second). "Handshakes"= a term used to describe the rate (and amount) of data transmission. I EC Blcctrotechnical Commission. Inductive loop antenna= an antenna constructed of a wire loop embedded in the pavement that couples energy via a time varying magnetic field passing through the loop. Interrogator = the ETC antenna that first identities or acknowledges a vellicle as it enters the toll plaza. khps = (kilobits per second) a measure of the speed of data flow (I ,000 bits per second) kHz = (kilohertz) a measure of frequency (1,000 cycles per second). Land mobile service= a mobile service between base stations and land mobile stations or b etween land mobi.le stati .ons. Land mobile station = a mobile station in the land mobile service capable of surface movement throughout the U.S. Land station =a station in the mobile service not intended to be used while in motion. Manchester encoding = an encoding technique in which a binary one is repres ented by a transition from a logic one' to a logic "zero" at the center of each b .it period, and binary zero is represented by an opposite transition. MHz =(megah e rtz) a measur e of frequency (I m illi.on cycles per second). Micro-= o .ne mil.lionth of a unit (i.e., 10'). Microstrip antenna =an antenna constructed of a patch of metal deposited on a dielectric s lab Microwave c high frequency electromagnetic signal with a frequency between 300 MHz and 300 GHz (delimiting frequencies vary). 1\

8 Optional non-mandatory portion of this evaluation, typically beginning no earlier than Wednesday night and lasting through Thursday. As an example, tltese evaluations included shadowing, anti-passback, transponder placement on trailers, multiple transpon ders in a single vehicle, etc. Passive system utilizes a transponder which takes its power exclusively from the radiating antenna field. Patch an array constructed ofmicrostrip antennas arranged in a two dimensional pattern. the particular state, either positive or negative with reference to two poles or electri fication. In ETC, this is defined as the action or of affecting radiation so that the s ignal wave assumes a different form. In most cases, a defined polarization (orie-ntation) of the transponder must be maintained to assure i t will be detected. Power density measure of the radiated field intensity in watts per squared centimeter, or the square of the electric field plane wave divided by the characteristic impedance of the medium. Read/write = a type of ETC technology where two-way communication exists The transponder is not only capable of reflecting unique pre-programmed data, but variable data in real-time can also be written, stored, and later extracted. REF= amplitude reference level for spectrum analyzer display or plot. RES JJW = (resolution bandwidth} determines how well the analyzer can resolve, or separate, two or more closely spaced signal components. RF = (radio frequency) a method of wireless communication which uses elec tromagnetic energy. Semi-active system =utilizes a transponder which has a self con taine d battery with an expected lifetime. "Shadowing" = a type of optional evaluation where vehicles follow as close as possible to e ach other as t hey pass thru the toll plaza lane io order to determine if separate vehicles are detected. "Smart eard" =a contact less (no metal contacts ensuring longe r wear and resistance to vibration}, credit card size, card that uses a self-contained microprocessor and memory to store and process such items as toll/fare or banking transactions, driver identification data, and telephone information. SPAN = the total width oftl1e displayed spectrum. SPAN OHz =a spectrum ana lyzer mode of operation in which the display is essentially a time doma i n repre sentation of signal amplitude at a parti cular frequency.


Spec t rum analyzer= a tool used in transmission signal analysis that can display peak signal frequency and amplitude variations on a logarithmic scale, and simultaneously measures volt ages. SWP = (sweep speed) the time at which tlJe e l ectron beam of the displ ay sweeps the screeo 'fDMA = (time division multiple access) a protocol that implies that sample values from several different lanes can be integrated into a single waveform. Transceiver = a radio device that uses many of the same c omponents for both. transmission and reception. 9 Transponder ("tag") = a radio device that typically, upon receiving a designated signal emits a radio signal of its own that is used for detection, identification, and loc ation. Transponders can be passive, or active. "Valid defined by CUT R according to a 4 part criteria. First, the correct vehicle in the correct sequence in the correct lane had to be acknowledged Second, a beginn i ng balance bad to be "read" from the tag and a new balance bad to be "written to the tag in order to consti t ute the transaction. Thi rd, the correct amount had to be debi t ed during the transaction. F i nally i f a known violator, a correc t and legible license plate image had to be produced. VES =violation enforcement system. Vagi ant enna = a type of antenna named after Japanese Professor H. Yagi, that is construct e d of a series of horizonta l r ods decreasing in length from front to back (Also a commonly used TV antenna). Zero span = an operating mode of a spectrum analyzer that allows the amplitude of a single freqllency to be ex.amined over time




I. EXECUTIVE SUMMARY The purpose of this evaluation was to examine and document performance capabilities and operating characteristics (features) of electronic toll collection (ETC) technologies, and deter mine what ETC technologies are available for 1993 procurement. It was !!l!l the intention of this evaluation to determine th e preferred vendor for procurement of an ETC system for the Florida Turnpike, or to eliminate any potentia l proposers for this future installation. Given the extremely short timeframe for evalua tion (a total of24 hours spread over three days with each participant), this evaluation does not serve as a statistically valid experiment but should be utilized to advance tbe general knowledge base of ETC performance testing. It is also important to mention that new conven tional toll collection equipment, expeeted to be installed by the Florida Turnpike over the next year was !!l!l integrated with this evaluation. Very little performance evaluation oftlte various ETC technologies has been formally documented, and for the most part that which exists is proprietary. (The majority of the perception toward ETC performance reliability good or bad, is vendor -generate d) Therefore "standard ized'' guidelines were not available to follow. The Center for Urban Transportation Research (CUTR) developed an evaluation protocol and configuration plan that was simple, consistent for each participant (i.e., "core battery evaluations), and as time permitted allowed for optional evaluations to explore kllown probJem areas or substantiate claims of performance. This eval uation served to estab lish a re lative basic performance indicator in tenns of percent of"valid transactions" includ ing integration of a violation enforcement subsystem (VES) component. Five participant "teams, wereevaluated be tween November I 992 and January 1993. These teams, in chronological order of evaluation, included: 11 AT&T Smart Cards Systems with Mark IV-IVHS Division, Mark IV-IVHS Division Amtech Systems Corporation Applied Computer Science with Saab Scania Combitech T raffic Systems, and Ml'S N etwork Technologies with Texas Instrumen ts and Saab-Scania Comb i tec b Traffic Systems. Two additional participants were scheduled to be evaluated during tltis evaluation period (Hughes Aircraft Company and AT/Comm, Inc ), but each bad to take themselves out of the Florida Departm en t ofTran sportation (FDOT) evaluation due to other priorities. An examina tion of these ETC technologies will be con ducted in some fashion, but not included as part of evaluation documentation. Under the environment of this evaluation process, and based on the examination of the five participant teams conducted by CUTR, several basic conclusions can be reached. 1 All participants were successfully able to demonstrate their basic operating charac teristics in the field, that were indicated in writing prior to their respective field evaluations. 2. No participant could consistently transmit and receive signals when the transponder was mounted directly behind the metal oxide (Sungate) windshields. 3. Power density measurements indicated a range below the national standards for exposure levels. 4. Based 011 total 'anomalies .. (jJlease see glossary), a g eneral indicator of readiness


12 and preparedness for the rigors of this evaluation success rates ranged from a low of70.8% to a high of 98. 2% 5. Based on valid transactions" (please see glossary) only, the participants exhibited a success reliability in the range of 89.7% to 98.4%. 6. Based on "valid transactions" w/lhoutthe VES component the participants exhibited success reliability in the range of 90% to /OO"A. (The other participants ranged from 96.3% to 99. 9%.). 7 Integration of violation enforcement capa bilities proved to be the biggest weakness for all the participants. CUTR believes this problem resu!Jed primarily from inad equate Integration between VES and ETC, not necessarily from inatkquate VES technology. Even the most successful participant had almost 37% of their photo opportunities resulting in bad or missing photos. The other participants had between 44% and 68% of their photo opportunities resulting in missing or bad photos. (The most successful participant was the only panicipanf that chose to incorporate a digital conversion process for its VES component) 8 Finally, given the brief examination of the ETC technologies in this evaluation pro cess, it appears that acceptable perfor mance reliability can be achieved FDOT should continue to move cautiously forward on their ETC procurement schedule Most importantly, adequate time (at/east 45-60 days) should be reserved for final performance acceptance testing uiUier a rigorous. controlled, integrated evaluation plan. II. PURPOSE AND SCOPE his the purpose of this evaluation to examine and document the general perfonnance capa bilities and operating characterist ics of ETC technologies. It is l1ll1 the intention of this evaluation to determine the preferred vendor for procurement and installation of ao ETC system for the Florida Tumpike, or to eliminate any potential proposers for this future installation. The documentation of this evaluat ion expands on CUTR's previous (qualitative only) evalua tion of ETC technologies and represents one of the first attempts to evaluate the performance of various ETC technologies conducted within a rigorously controlled time schedule under pre determined evaluation parameters. Given the extremely short timeframe for eval uation (24 hours over three days with each par ticipant) this evaluation does not serve as a sta t istically valid experiment, but will be uti lized to advance the general knowledge base of ETC performance testing. Additionally, the evaluatioo findings will provide some assis tance to FDOT in the development of a system wide ETC technology performance specifica tion. The field evaluations have occurred over a three-month period (November 1 992-January 1993), with the overall project constituting a twelve-month, research and documentation effort. It was CUTR's goal to maximize the opportunity to capture field perfonnance data under varying conditions during the three month, field evaluation timeframe . New con ventional toll collection equipment expected to be installed by the Florida Turnpike over the next year was l1llt examined or integrated as part of this evaluation


m B ACKGROUND CUT R established a "core bat tery" of evalua tion parameters such tbat all participants would be s ubjected to similar condit ions. "The areas of performance d u ring 6eld evaluation included: reliability (with and with out violatioo enforc& ment), and the a bility to demonstrate operating characte ristics (i.e., signal power l evel, trans mission freque ncy, and data tr:rnsmission rate) 111 e following "core batte ry" of eva luation parameters wer e a pplied and assesse d to the great est extent possible durin g the 6eld performance evaluation: I Varying vehicle speeds (S-mph incre menls, stop-n-go t o SO miles/hour). The Florida H ighway Patrol assisted with high-speed (greater than 25 m .ilesl hour). 2 Varying vehicle ty pes (passe nger cars vans, li ght trucks, and h eavy trucks), progression s equence, and ga p s be twe e n vehicles Higher speeds required larger gaps between vehic l es for safety. 3. Varying degrees of windshield tinting (me ta l oxide) and angling 4. Inclusion of a violation e nforcement subsystem to be int erfaced with the ETC system (proc essing license plate images during dayli ght, tw ilight, and nighttime period s). CUTR solicited operating characteristics from each participant pri o r t o the commencemen t of 6eld evaluations. These range of stated operat ing charac teristics, listed in T abl e 1, w.:re confi rmed to the greatest extent possib l e during the field perfonnance evaluations. 1 3 11tc Sawgrass Expressway (two side by -side lanes at t-h o Sunrise main li n e plaza), was selected by the FOOT T um pike Office as the venue for til e ETC fiel d performanc e evalua tions. This location is about 12 mile s west of downt own Ft. Lauderdale, in B roward Couoty, Florida. FOOT took the lead role in initially contacting parti cipants and establishing their respective commitment and liability for participation. CUTR coordinated with each participant regardin g eva luation protocol, time periods of evaluation plaza equipment installation and removal maintenartce-of -traffi_ c, and insta llation o f transponders. FDOT published a "Letter of Interest solicita tion re garding the ETC 6eld evaluations in the Florida Administrative Weekly and seveml other nationa l publications. FOOT sup plied a fleet of I 0 vehicl es and vehicle operato r s for this e v aluation T h e eva luation fleet consisted of the followin g vehicle types : S passenger cars 2 -commercial vehi c les (5 ax l e box trailer, 5 ax l e fla t bed) 2 -vans (o ne with metal oxide wind shie ld) I -pick-up truc k CUTR convened a prefield performanc e e valuat ion scope meeti ng (September 30, 1992), mandatory for participants to attend, a t the Sawgmss Expressway toll administra tion building (Deerfield Plaza). The pwpose of this scopin g meeting was to facilita te questions and an swers, discuss the publica tion of fmdings,


u t.tODUtAOON TYPf System Operating Information 'liME: O.IIQ.J9, 4 ktl. 3804 k1> RS 232C 0 9000 8A.UD Olt RS 422A G I ((I( BAOO. BArTER'VUff review evalualion protocol and parameters, visit and inspect the evaluation site (Sunrise line plaza) and conduct "lot tery-style" drawing for partici pant evaluation schedule. All eosts associated with ETC equipment installation and removal was the responsibility of the participants Advance warning signage and channel ization devices were the respon sibility of FOOT. CUTR repre sentatives were present at the evaluation site during all field performance evaluations During this time CUTR was responsible -for monitoring p er fonnance evaluations (i.e., obtaining a hard copy printout and license plate image (if ap plicable) from the participant immediately following each vehicle fleet passage), complet ing a performance test diary (a separate page for each vehicle configuration passage), and cataloging the field performance evaluations on video tape and 35mm color slides.


IV. EVALUATION PROTOCOL AND CONFIGURATION PLAN A. Other ETC Performance Ev a luations Very lillie performance evaluation of t he various ETC techno l ogies has been formally documented. CUTR bas investigated the extent to which performance evaluation and testing of BTC toohnologies has ooourred (o r is planned to occ ur) Thi s investigation has serv ed to obtain age ncy feedback and guida n ce in t h e l'DOT eva luation. Many of the toll collection agencies that have implemented o r are investigating llTC systems have conduc ted some type of performa n ce testing. H oweve r much of this evaluat ion bas been conducted under uncontrolled conditions. Unfortun ately the finding s of these evaluat i ons have n ot been formally docum ented and published, and in many cases the results are proprie tary. F urther more, test plans that are ava ilab l e ind i cate t hat these evaluations were n ot sta ndardized t ests and sati sfy only s pecific age n cy concern s or requiremen ts. C learly there is a need to establish a nati onally accepted, standardized testing procedure, such that all industry vendors could be "pre -quali fied" in a co nsistent manner by an independent, unbiased, national stand ards age n cy. The res ults of these standardized tests s hould al so be avaHable to anyone wh o reques t s them. Table 2 s ummarizes tl1e general s t a tus o f ETC porfonnance evaluations B F OOT Evaluatio n Parameters Evaluation Periods and Participants Tile T uesdayWeduesdayThur sday dates available for the five field performance evalua-1 5 tion participants were d rawn in lo ttery-sty le" fasbion as follows: J. AT&T Sma rt Car d s Sy stems and So lu t ions (Bri dgewater, Nl)/Mark IV -IVHS Division (Ontario, Ca nada)Novembe r 17-19 1992. 2. Marl< IVIVHS Div ision (Ontario, Canada)ffecnicon, In c (Lafayette, NJ) -December 1-3, 1 992 3 Amt ec h Systems Corporation (Dallas, Texas)D e cember 8-10 1992 4. A pplied Co mputer Scien ce (Norway)/ Saai>-Scania Combi t ccb T r affic Systems (S\veden and United IGngdom)-Janu ary 5-7,1993. 5. K iewit (MFS) Network techn o l ogies (Oma ha Nebraska)ffexas Ins truments (Da lla s, Texas)/ Saab-Scania Co mbitech Traffic Syste ms (Sweden and United K ingdom)January 1 921, 1993. Two additional partici pants (Hughes Aircraft Company and AT/ Comm, Inc.) responded to FOOT's solicitation, a ttended the September 30, 1992, scoping meeting, and were sched u led for evaluation . Unfortunately, these two participant teams eveutually had t o drop ou t of the ir scheduled evaluat ion s. lt w as the intention of this schedul e to a l s o afford participants the opportunity to install and pre>test their equipment no m ore than two day s pri or t o their r espec ti v e evalua tion dates, and remove their equipmen t within t:"'o days following their respective evaluation dates. This st r ict ond rigorous schedule was adminis tered to each participant to ba sically observe their ability to perform under time>pressure conditi ons.


16 Table 2 ETC Field Perfonnance Evaluation Status AGENCY New Hampshire Bvreau of T urnpikes E-Z P ass Group : Penn. Turnpike Commission NJ Highway Authority (Gorden S t ale Parkway} Port Autho r ity of NY/NJ NY State Thruway Tribotough Bridge & Tunnel Authority NJ Turnpike NY Bridge Author i ty Ill i nois S t ate Tol l Hig hway Authority Ortando-Otange County Expressway Authority STATUS Have tested AT/Comm No resu lts were pub lished No reports available Started testing Dec. 16 1991 100 vehiCles, 2 l anes ( s idyside} Completed Dec. 199 1 tesbng within 4 weeks Need better (reconciliation of reports) and more coordination with vehldes About t o commence a new round of testing of severaJ vendors' Pennsylvania Turnpike Commission: Tested Eureka and Mark IV for 6 months Did not publish fi ndings Had speed problems raa dlng transponders (ie:ss than 3 mph) New Jersey Highway Authority (Garden State Pafi

Table 2 (Cont.) ETC F i e l d Perfonnance Evaluation Status AGENCY Virginia DOT (Dulles Fastoll Proje<:t) cast l e Rock Consultants (HEL P Cresoent Caltrans (planned private, public/private toll roads) Harris County (Houston) Tollway Authority-(Sam Houston To llway) (Hardy Tollway) Turnpi ke Association ( IB TTA) Ontario Ministry o f Transportation Florida DOT (Tumpike Offioe) Tra n sport Canada Office o f the Deputy Assistan t Secretary of Defense STATUS Tested Amtech -1991 Tested Mal'k IV, KiewitTexas In struments 1992 Selected Kiewit (MFS} Network Technologies and will use the TIRI&-1 equi pment (formal award not yet m a de ) Test plan s o r re&ul ts are not available HELP/ A V I final report is availa ble ( very informative) Provided "Compat ibility Specifications for Automatic Vehjcle Identification Equipment Published an RFP to implement electronic toll collection on Caltl'ans bridges. and Issued AVI compatibility s.peeirlcation in March 1993 as part of a stafewtde toll system procurement Lawrence Uvennore National Laboratories hav e developed a prototype AVI system specification for Caltrans whic h uses micr o wave backscatter technology Tes t & monitor their system for rel iability Have an Amtech &yef&m (pr i me as demo project next Installation oomplet e d and operation began i n l ate October 1992 a t both to lt facilities on Had planned t o do testing, but it was cancel ed Planning to tes t readtwrite technology with co n n ection to a smart car d at a later date Five participant teams took part l n controlled field perforrnanoe evaluations (November 92 -Janu ary 93) Only read/write technology was evaluated Viol at io n enforcement subsystem also was evaluated Findin gs will as-sist in developing system wide perfonnane& speCifications. RFP f or procurement a n d installation expected to be advertised Nov. 1993 Not doing any test ing, but they are looking a t the techno logy used I n the HELP project (Marl< I V) They want to have a n integrated system with about 38 differe nt applications T hey a re investigating RF technology for. ( 1 ) Asset location (2) Data T ransfer C urrently wor1 d ng on AVI system standard


18 Participant Requirements I. Two Janes of"read -write" ETC equipment were installed by participant in the toll plaza Janes. Power source book-ups and conduit runs were reviewed at the Septem ber 30 project scoping meeting. These two Janes (Lanes I and 2, closest to the eval ua tion work trailer and plaza administration building) were utilized l:l

19 C WB40, car, pick-up truck, car, van, low, in S-mile/hour increments b eg innin g van, \VB40, car, car with sto p and go (A) to 50 miles/hour D c ar, van, car, WB40, l>ick-u p truck, car, {K). WB40, van, car, ca r A stop & go {2.Smph avg.) E =car, car, van, pickup truck WB40, B a5mpb Ca IOmph van car, \VB40, car, car 0 ISmph F = Florida Highway Patrol car {speeds E 20mph F=2Smpb. greater than 25 mph only) G 30mph 5. Te n veh icle sequences (0-P} grouped in H 35mpb I = 40mpb pairs of five as shown below, for dual-lane J 45mph reconciliation were utilized such that each K SOmph v eh i cle type was with each o ther ve hi cle type as they passed through 7 Evaluations commen ced no earlier than 9 the toll plaza a m and ended oo later than 5 p .m. { except G (14 -foot Jane)= car car, WB40, car, on Wednesdays which were reserved for nighttime photographic surveillan ce/en WB40 forcement evaluations) to avoid the momH ( 1 2foot lane) = van car, van, car, ing and e vening peak-hour troffic Evalua-pick -up truck tions were conducted in the non peak (northb o und) traffic direction. I (14 foo t lane)= WB40, van WB40, car, car 8. Typically, one break durin g the d ay (Thes J (12 -foot Jane)= van, car, car, pick-up days and Thursd a ys) occurred during lunch truck, ear at I p m 2 p.m Oo Wednesdays two breaks occurred during lunch at 12 p m K {14-foot lane)= car WB40, van, WB40, 1:30 p m., and dinner from 5 :3 0p.m.7 car p.m. Typically, nighttime evaluati o n s o n L (12-foot lane) = car, va n p i c k -up truck Wedne s days began about? p .m. and con-car car tinned un.til I 0 p m If evaluati o n s were o n sc hedule, this left abont 1.5 hour s to M (14foot lane) = van W B40, pick-up begin opt i ona l evaluat .ions on Wednesda y truck WB40, car night. N (12-foo t lane)= car, van car, car, car 9 F or safety purposes vehicle fleet speeds of 0 (14-foot l ane ) = van, car WB40 car, 30 mph-50 mph were run for vehicle st>-WB40 qucnce "F" only 1b.is sequence was typiP ( 1 2-foot l ane ) = van, car, ca r car cally run just before the dinner break on pick -up tnlck Wednesdays. Four p asses were made for 45 mph (two with v iolation enfor cement 6 Eleven vehicle fleet speeds (A-K) for rea ctivated) aod four passes were made for conciliation were utilized as shown be50 mph (two witb. violation enforcement


20 activated). This configuration (6g-6k) was always conduct ed with a s ingle Florida Highway patrol car. 10. Evaluation of the YES was incorporated following the Wednesday lunch break through the end of Wednesday night. I I. Typically Thursday was reserved for optional evaluations (i.e., shadowing, cross--lane reads, transponders on trailers, anti-passback, etc ), participant showcas or re-runs of "core battery" evalua tions that could not b e completed. Eva luation Table 3 illu s trate s the 65 d i fferent fleet vehicle configurations that were utilized in the battery" evaluations for each participant. Eacb configuration was run twice. C. FDOT Evaluation Plan Based on discussions with consultants and ag encies who had previously attempted to obtain ((handshakes" and data rate verification, one aspect in obtaining these measurements was found to b e mandatory: reliance on direct ven dor participation and assistance. Having the operating specifications from each participant alone did not ensure that these measurements could be made, especially considering the rela tively short time this particular evaluation spent with each participant. There are too many vari ables outside of evaluator control, such as the specific data encoding and transmission scheme for each participant, to permit field verification and measurement. Therefore it was concluded that the electrical measurement technique could not be "standard ized". Furthermore, depending on the specific participant modulation and encoding scheme it could also be impo ssible to take a measurement of data rate transmission or Hhandshakes,. out tapping into an inte rmediat e frequency (or data output) signal from the ioterrogator. lt was imperative, therefore, that CUTR had direct assistance from the participant to efficientl y monitor transmission signals over time in order to separate cartier signal and background from actual data transmission. Given the timeframe and participant evaluation schedules for this evaluation, it was recom mended that the following protocol be intro duced in order to provide for the highest pro bability of successful and accurate field mea surements. I. A standardized sy stem infonnation table was completed by each participant and transmitted to CUTR no later than at least one week prior to their evaluation period (summarized previously in Table I). 2. The presence of a technology/operations "expert" was required from each participant to assist CUTR in field measur ements and interpretation (this requirement later proved to be critical). 3. The participant was required to demon strate that read/write occurrences were taking place, and the rate of read/write transmissions and the number of"haud shakes" per vehicle passage In order to conduct this demonstration it was neces sary for the participant to also bring their own field equipment for the evaluation period, such as a digitizing oscilloscope and a means by which to ge t hardcopy of screen. II was the responsibility of each participant to ass ist CUTR by suggesting how best to verify t his demonstration, and provide a hardcopy printout for each configuration run.


======================================21 4. The data to be "re ad from the transponde r was the beginn ing accoun t ba lance upon ente ring the toll for each configura tion run. The data to b e "written" to th e trans ponder was the account balance fol lowing e a ch t oll transaction. The actual real-time for each read/write occurrence was also recorded as part of the hardcopy printout This time reference was synchronized and cross-checked wifl.1 dle video timer a s CUTR video documented each evaluation. 5. At least one traosp onder wa s affixed t o eac h vehicle. For evaluation fleet veb.icles with metal-oxide windshields, at least one of the transpcnders was to be affixed be hind the metal-oxide w i ndshield. (By choosing to install an cx.terior transpcnder or an interior transponder in a location not directly behind the metal oxide windshield on the with the metal-oxide wind shie lds, the participan t was admi tting his inability to avoid signal atte nuation) V. EVALUATION FINDINGS A. General Operati o n of ETC Syste ms Introduction The adve nt of low cost, custom integrated circ uits (ClCs) has introduced t h e possibi l ity of allow ing not on l y two-way co mmunication but a l so o n-board pro cessing and driver interaction dming the ETC process. It now appears possible for toll information to be stored o n the vehicle and processed in a variety of ways. For example, there could be different accounts (representing different toll authorities) with d iff ere nt rates and other information on on. e tag. Current ETC systems genera lly take advan tage of two-wa y (read/write) techno logy and onboard processin g. Th.is section of the repo rt gives an overview of the ETC t cc h nologi es evaluated and th e ope r aHog prin ciples upon which those techn o logie s are based. The var i ous comp onents of a typical ETC system are identi fied, and t he genera l op eration of an ETC system are diseussed by examining a typi cal two-w a y communication sequence ( t ransaction). Fmally the different f eatures afforded by the u niq ue operating prin ciples of the various ETC systems are outlined. System Requirements The general requirements for an ETC system are to provide a means of automatically charg ing a toll to a vehicle passing through a toll booth without the vehicle needing to stop The system must be extremely reliable (at least as reliable as conventional toll collection equip ment, given trade-offs in th roughput, cost, etc.), under all weather co ndi tions, and it must be immune t o varying E lectro-Magneti c Interfer ence (EMI) in the local environment. Fo r purposes o f this eva luation, the system must have the ability to store th e toll infom1ation and other data on the transpcndcr C'tag") and modify thot information as the vehicle passes through the toll plaza it must have read/ write capability). Specifically, the system m ust b e resistant to: Int erference from transactions being con dueted on adjacent lanes (cro ssl a n e reads) Signa l transmission r eflections from the p l aza structure an d other metal objects. Nearby EMl sources {pager' s, cellular telephones, etc.) Intentional efforts to compromise the sys tem through: counterfe it tags illegally adding money t o the tag


22 Table 3 Evaluation Configurations CONFIGURAOON SINGlELANE DUAL LANE SKIUENCE SPEED NUMBER I X A A 2 X A 8 3 X A c 4 X A 0 6 X A E 6 X A F 7 X 8 A 8 X 8 8 9 X 8 c 10 X 8 0 II X 8 E 1 2 X 6 f 1 3 X c A 14 X c 8 15 X c c 16 X -c 0 17 X c E 1 8 X c -F 19 X 0 A 20 X 0 8 21 X 0 c .; X o [) X 0 e 24 X D F 25 X E A 26 X E 8 27 X E c -; X E 0 X E e 30 X E F 31 X F G 32 X F H .:;


===================================:::v CONFIGURATION NUMBER Table 3 (Cont.) Evaluation Configurations SINGLE IANE DUAL lANE SEQUENCE SPEED


24 The ETC system might also provide some means of automati c enforcement of toll violations. In accordance with recently passed state of Florida legislation, the system will be capable of taking a photograph. of the license of any vehicle that has a bad tag, a tag w1th zero balance, or no tag at all, and send the warning o r ticket to the vehicle owner. Finally, the system must be easily interfaced with existing equipment, automatically pro vide for malfunctioning equipment (redun dancy), and provide for the easy management and retrieval of the database generated by the system. Anti-fraud protection is particularly 1mportant. While it is highly improbable that someone could steal and manufacture the cir cuit design for the custom integrated circuit of a particular tag, as the equipment for manu facture is not commonplace, it is COJlceivable that someone could break the code for the tag and illegally program it Parts of a Sys!ern(fypical Transaction Sequence The components of an ETC system are listed below and illustrated in F igure I. Transponder/tag Plaza computer Antenna/RF module Reader Violation enforcement system Lane co.ntroller (optional but desired in Florida) Differe-nt vendors may combine the various functions pe rformed by these parts into a sing le device but all of these parts are present. Transponderaae The tag is the vehicle-mounted de vice that re ceives signals from the toll plaza demodulates those signals into information that can be pro cessed and stored on the tag and transmits in formation back to the toll plaza. There are several types of tags that correspond to the types of communication that take place be tween the toll plaza and the vehicle. The defi nitions that are discussed could more precisely be called conventions as the status of ETC transponder technology is currently in a state of flux. The different types are: passive, semiactive, and active. Passive refers to a system based around a transponder that has no power source. In this case the transponder simply reflects the signal back to the antenna A sem i passive transpond er reflects the signal also but has more sophisticated on-board processing of data. A semi-active transponder does not reflect but actually transmits its own signal using stored energy in a self-contained battery The term semi refers to the fact that it requires a prompting signal to begin its operation. An active transponder transmits its own signal, and generally derives its power from the vehicle. The relatively rapid evolution of ETC transpon ders has progressed from a Type I transponder that can only be "read" (or simply reflect a unique vehicle identification when interro gated), to a Type fi transponder that can be from as well as "written,. back to in order to store and update unique variable data contained within tlte tr ansponder such as entry/ exjt locations, account balance, vehic1e mainter nance and inspection reports, etc. Type Ill transponde rs are also available, which perform as Type U, and also have the capability to in teract and communicate with the driver. Costs generally increase from a Type I to a Type Ill transponder.


25 Figure 1 Lane Controller Typical Components of an ETC System LANE READER PLAZA COMPUTER RFMODULE RF MODULE The function of the lane controller is to integrate all the activity that occur.; in a toll lane. The extent of responsibility that the lane controller assumes varies from vendor to vendor. However, the minimum function in all the different systems is to send the toll transaction information in its final form to the host/plaza computer, and to effec tively trigger the violation enforcemen t system. For some systems the lane controller also takes on some of the responsibility ANTENNA V.E.S. I TAG I ANTENNA Antenna/RF Module The roa dside ante .nna comes in many forms depending on the choice of the vendor. For low frequencies (e.g., 130kHz) the antenna is an inductive loop embedded in the road pave ment. Most higher frequency (microwave) systems utilize overhead or side-mounted antennas. The RF module contains the cir cuitry required to modulate a microwave signal with the digital data to be sent to the tag (transmit), and de-modulate the microwave signal received from the tag (receive). Reader The reader takes the demodulated signal from the antenna!RF module and converts the digital signal into a form readable by the host computer. of the data processing from the reader. Plaza C'.omputer The plaza computer is the final processing stage for all the data generated by system It takes the toll information from the readers from each lane, the picture from the YES, and acts as an infonnation manager. The toll plaza functions required for this system are to identify the tag, process the inf ormation stored on the tag, write back to the tag. and control all the other functions of the toll plaza. There will usually be one host computer for the entire system one plaza computer for one or several toll plazas and one lane controller and reader for each lane. How the different functions are divided between the three parts varies from vendor to vendor, but together they will perfonn the same general functions.


26 Violation Enforcement System The YES consists of an int e rface to the lane controller, a camera for eac h lane, a triggering system to ensure that the picrure is taken when the tran spon der i s in the center of the v eh icle, an d a storage media for t he picrures The prim ary differences between the different YES systems are i n what fonn the images are stored and at what point the images are c on verted into differen t fonns. The digitizing camera immediately converts the image into digital fonn for storage on a floppy drive The analogue/ digital system uses an analogue camera for each lane and a single d i gitizer or "frame grabber for convers ion into digital fonn. The all-analogue version never converts the images t o digital fonn but stores the imag e on a video tape for later e xt ractio n b y a toll plaza employee There i s no provision for autom atic extraction of thelicense plate photo graph under the all-analogue system. The timing between the det ection of the end of a vehicle and the taking of the pictures is very cri tical for the legibility of the license plate image. V ehi c l e pre sence and vehicle separation also are important elements in accurate and relia ble picrure taking. Lighting i n the toll plaza may v ary from plaza to plaza, and this may also affect the ability to produce legible license plate images. Normally the lig hting level in the area under the plaza canopy should be 25-foot candles. T h e Sunrise mainline plaza canopy was over 20 feet high (atypical), and thus s peeific adjustment in ba c kground lighting for this ev aluation made by eac h participant \\'3S considered to be atypi cal B. Operating Characteristics ofP articipants The following is a descripti o n of the five ETC system operation s as observed by CUTRIUSF fromNovcmber 1718,1992toJanuary 19-21, 1993. System 1 Oyezyjew Thi s system was ao active read/write system. The transponder is eithe r windshield-mounted internally or front-bumper-mounted externally, and is capa ble oftwe>-way communication As tlte vehicle passes the reader site, it enters the field o f view of an activation antenna. The antenna transmits a 20 micro-second activation signal (trigger) to the transponder ca using it to r espond with its ID message Since the system functions i n a two-way commun ication mode coded data are not only passed from the vehicl e to the roadside unit, but data flow also occurs in the reverse direction, with a coded da t a mes sage transmitted from the same antenna which functio n s as the transaction cycle antenna. The transponder stores both fixed code messages and variable code messages In the two-way communication mode, first fixed codes are passed from the vehicle to the roadside, then variable messages ( e.g., account balance and debit) are passed between the roadside and the vehicle The system uses either an overhead Vagi or a s l o t (in-pavem ent ) antenna for sending and r eceiving RF signals. The overhead antenna i s u sed to commu nicate with an internally mounted transponder while the inpavement antenna is preferable when an externally m ounted transponder is used. Figure 2 illus trates the test configuration for this system. In order to represent the transponder's data message on the transmitted RF signal, thi s system utilizes unipolar amplitude s hift k eying (ASK) modulation. This system u sed cyclic redundancy checking (CRC) t o det ec t errors in the messages. CRC addition of a block c h eck sequence (BCS) of bits to the data


Figure 2 System 1 Test Configuration Spectrum Analyzer Vagi / Antennas"' Communication Area" USF/CUTR Tost Antenna t message t o be transmitted. The RF module performs a logi c al division of the whole data stream (message plus BCS) and should obtain a 7.ero remain d er if no error has occurre d Since tbe central unit covers multiple Janes, a lime division rnu. ltiple access (TDMA) protoc o l is used. lll TDMA, values from several differ e nt lane s are integrate d in to a single time wave form. System 2 -Overview 1bi s system was an active read/write system. The cardreader (which a smart card is i nserted) is a dashboard -mounted or wind shiel d -moun t ed unit. The contactless card contain s both a microprocessor as well as 3 k bytes memory. The card stores both fixed code messages and varia ble code messages. The fixed code messages allow vehicle identifica tion data (serial number) t o be encoded on the lnPavement Antenna 27 transJ?Onder prior to its installat i on on the ve h i cle. Once encoded, the data message on the transponder is perma nent. The variable co d e data such as account b alance can be updated during the write cycle, as the veh i c l e goes through the toll plaza. As the vehicle passes tbe reader site, the following sequence occurs I t first enters the field of view of an overh ead Yagi "activation,, antenna. 1be antenna transmit s a 20 m i cro-second activa tion s ignal ( trigger) to the trans-ponder, causi n g i t to respond witll its ID message. Since the system functions in a two way communication mode, coded data are not only passed from t h e vehicl e to the roadside unit, but data flow also occurs in the reverse direction, with a co d e d data messag e transmit ted from a second overhead Vagi "transaction" antenna. Figure 3 illustr ates the test co n figura tion for this system. In the two-way communi cation mode, first fixed codes are passed from t h e vehi cle to the then variabl e messages are passed between the roadside and the vehicle. TI1e system uses overhead Yagi antennas, prim arily in order to avoi d problems associated with a beam passing into adjacent lanes. By limiting the overhead antenna beam width to the lane width, cro s s-lane interference is minimized, allowing the system t o operate in a multiple-lane environment. In order to represent the transponder's data on the transmitted RF carrier signal the system util izes the digital modulation


28 F igure 3 System 3 Overview System 2-Test Configuration This system was an acti\'C read/write system. The transpon der is a windshield mounted or exterior unit containing a condi t ioning circuit, clock oscillator memory, mic-rostrip antenna and an i nterna l lithium battery. The battery, which bas a lifetime of approxi mately five years, classifies this system as a system The transponder stores both foxed code mes sages and variable code messages. Transaction Antenna Activation Antenna Communication Area : : : : Communication Area Spectrum Analyzer USFICUTR Test Antenna Transponder '"Coneoptual.dJ.agram onty, not to scale. technique called unipolar ASK. Error control methods are very important for any data communication system. The serial nature of high speed data stream tends to propagate errors; therefore, means must be provided to detect and correct these errors when they occur This system used CRC to detect errors in the messages. CRC involves addition of a block check sequence (BCS) of bits to the data message to be transmitted. The reader unit performs a logical division of the whole data stream (message plus BCS) and obtains a zero remainder if no error has occurred Since the plaza computer covers multiple lanes, a TDMA protocol is used. TDMA implies that sample values from several different lanes can b e int egrated into a single waveform The time interval containing a complete, single-lane, cycle is ca lled a frame." Each 850 micro second trigger/read/write/verify cycle repre sents a frame. A frame consists of a 20 micro second trigger signal followed by 256 micro second read cycle which identifies the tag !D. As a vehicle enters tl1e toll plaza, the following sequence occurs. It first enters into the field of view of an i nductive loop antenna. The in ductive loop antenna has a low frequency (100-120 kHz) signal running through it. Any vehicle (with or without a transponder) passing over the antenna, will disturb the antenna mag netic field, causing an RF microwave signal to be turned on and tran smitted through a second overhead nboxed" antenna. The overhead antenna will transmit a continuous wave (CW) signal. At this point, if the vehicle has a valid tag, the tag will modulate there flected CW signal (backscatter), modify a por tion of the signal and reflect it back to the an tenna. The reflected signal carries the trans ponder identification code. Figure 4 illustrates the test configuration for t his system. The transponder contains a battery which keeps it continuously s crolling its content There is a single bit that will flip itself when there is


29 Figure 4 System 3 -Test Configuration changed between two discrete values. Ea c h frequency is generated by a separate osciUator emb edded in the transpon der Also with tbe FSK modula tion technique, the log i c levels arc repr<> sen.ted by s uccessive pulses. OVerhead Boxed Antenna Spectrum Analyzer C ommuni cation Area USF/CUTR Test Antenna Inductive Loop Antenna Transponder conceptual diagram only not t o scale. This system used CRC to detect errors in the messages. CRC involves add i tion of a block check sequence (BCS) of bits to the data message to be transmitted. Th e reader uni t performs a l ogical divi sion ofthe enough RF power incident on th e transponder. Once the software identifies the flipped bits, a write/verify cycl e occurs which comp letes the tran s a ction. Tbe rn.ain concern associated with the overhead antenna i s to make sure that the pattern will not exceed the width of the Jane. The appropriate pattern is achieved via tb ree directors locat e d on each side of the "b oxed'' antenna. As the directors are squeezed down, a finer beam is achieved at the expense oflarger side l obes (unwan ted directions for antenna recept ion or transmission). As the d .irectors are opened up, tbe antenna pattern will be wider but shorter. By limiting the o verhead antenna beam width to the lane width, cross lane interference is minimized, allowing the system to operate in a multiple-lane environment. This system utilized freqoency shift keying (FSK) modulation. In this FSK implementa tion, the transponder transmission frequency is whole data stream (message plus BCS) and shoul d obtain a zero remainde r if no error has occurred. Since the p laza computer covers multiple lanes, a 1PMA protocol is u .sed. TDMA implies th.at samp le values from several different lanes can be integrate d into a single waveform. The time interval containing a complete, single>lane cycle is called a frame. Each transponder message contains two frame.<; one of fixed data and the second o f variable data. System 4 Overview This system was an inductive, l ow frequency ) system utilizing a pas sive transpo.nder. The demonstr ated equ i pment was operation .al only under the read mode. The transponder was an internally or externally mounted unit (an ex terna l tag was utilized in the core" battery evaluations) con taining a small ferrite antenna,


30 Figure 5 System 4-Test Configuration Inductive The low operating frequency and induc tive loop antennas classifies this system as an inductive system. Due to the low fre quency, th e communi cation method used is "direct broadcast", which is very similar to two transceivers or a "walkie-talkie". As USF/CUTR Loop Test Antenna Antenna Spe<:trum Analyzer Transponder -conceptual diagram only, not to sc.le soon as the lane controller transmits, the information is received by the vehicle transponder, and there is no need to set up any communication protocol with the system. Data flow microchip, and two capacitors. The transpon der is powered by RF energy from an in-ground loop therefore, this system was classified as a "passive" system (This type of system is sometimes further classified as driv en" as it is energized by the RF fields). Figure S illustrates th e test configuration for this system. As a vehicle enters the toll plaza, the following sequence occurs. It first enters into the field of view of an inductive loop antenna. The anten na is powered by an alternating current from the lane controller, creating an electromagnetic field in the vicinity of the loop. The antenna, whose pattern covers th e entire lane width, has a low frequency signal running through it. If the vehicle has a tag, a voltage is induced by the loop antenna into the transponder's ferrite antenna which charges a capacitor. This meth od of energy transfer via inductive coupling is equivalent to the transfer between primary and secondary windings in a transformer occurs only from the vehicle to the loop antenna; therefore, this was a one-way commu-nication system. System 5 Overview This system was a semi-active read/write sy stem. This system was capable of addressing specific address fields in the transponder much as a microprocesso r would access memory. The RF module/antenna was placed on the l eft hand side of the toll lan e ata height of I 0 feet above the roadway. Figure 6 illustrates the test configuration for this system. The two central features which describe this system are based on the concepts of circular polarization and the concept of memory addressing. Different polarization directions are used for different portions o f the transaction, clock wise is used for reader to transponder commu nication and counter-clockwise is used for


Figure 6 System 5 -Test Configuration Mlcrostrip Patch Array Communication Area" USF/CUTR Test Antenna Transponder 31 data length, checksum length, and CRC check, are not what they should be the reader will know this is a bad tag. Spectrum Analyzer conceptual diagram only, not to seale. The transponder for this system is a semi active type .requiring a start-up procedure before it can begin communicating. The RF module/antenna is a single unit device that modulates the Manchester encoded digital signal, from the reader, onto a microwave signal for transmission. The polarization of the transponder to reader communication. The transponder and reade r are both designed to exploit this concept by being tuned to the dif ferent types of polarization. The use of switched polarization reduces the probability of interference from sporadic reflection. The concept of memory addressing is borrowed from microprocessor practice. Whereas most other systems transfer the entire contents of the tag at one time (data frame), this system can access any given portion ofthe tag's memory at a time. In addition, it is possible to vary the number of bits that are read before a checksum is conducted. The reader/lane controller can then treat the tag as just another memory ad dress. If the reader determines that there is difficulty in conducting a successful transac tion, it can decrease the number of data bits before it conducts a checksum, thereby increas ing its reliability. Th. ese features also give the ability to encrypt the message just by using the capacity of the system. If the data location, outgoing waveform is rotated for transmission to the transponder. This system demonstration decided to integrate the RF module with the antenna to boost the r:ange between the antenna and the lane control ler/reader. By performing demodulation at the antenna, only a low frequency data cable is needed between the antenn.a and the reader, in contrast to a length sensitive RF cable. C. General Test Plan for Electrical Field Measurements Electrical Test Procedure All the electrical testing on the participating electronic toU collection systems were con ducted in a static, controlled, environment. A static environment as used here implies that any vehicles used during the measurement process were stationary, and not moving through


32 the toll plaza. Table 4lists the test equipment used by CUTRIUSF to obtain the electri cal fie l d m easurements. Table 4 3. F r ame Rate and Bit Rate Verification Frame rate as wel1 as bit rate \ erific ation were carried out using a d i gitizing oscillo E l e ctrica l M easur e ment Equipme n t Lis t ing scope. By connecting the oscilloscope to the partici pant's RF transmission module and running the system (in some cases using vendor-supplied diagnostic software"), both frame and bit rates were witnessed and verified to the extent possi ble . E QUIPMENT ITEM MAKE AND MODEL Spectrum AnoiYlCf Hewl ett Pockord+IP85920 Rod!onon Monitor No r do-No r 3616 P l o tt e r Hewlett POCkOtdH P7d40A Spectrum Anal yzer Plots Ant (tl'lno Krt AH. Svstems4AK18G Osciii0$Cope Go'-'d 200 M hz (050)4094 A spe c trum a nalyzer is one ofthe most powerful tools availab .le in s ignal analysis. The analyzer's graphic I. Signal Level Detection--Signal lev el detec tion was carr i ed out using an R F hazard (radiatio n ) monitor. lfthe monitor sensi tivity was not high e n ough to properly detect the power density levels (which was the case for all the participants), a spectrum analyzer in conjun c tion with a calibrated antenna was used. 2. F requency Allocation Verification-Tite The parti c ipant's transmission (or carrier) frequenc y p r esen c e in the FCC allowable bands" was verified using a spectrum analyzer. f"i\'4? panl cular frt(}uency bonds within the microwa\e region are permitttd by t he Federal Commuication Commission (FCC) for AVI systems. 11wse al"t 9/ S (tor 13) Mllz 2450(+ or15) Mil: 5800(+ or l5).1fHz. 10525 (+or-25) MHz. ami U 12.5 (+or.SO) MHz. representation has two axes, frequency and amplitude One of the most desirab l e features of a spectrum analyzer is its ability to simultaneously measure voltages whi c h differ by a factor of 100,000 or more. The wide range is displayed by using the decibel, or dB, which is equa l to 20 times the logarithm of the ratio of one voltage to anot h e r or ten times the logarithm of the ratio of two powe r s I f one voltage i s twic e the other it is six decibels( + 6dB) greater (if i t were half, it woul d be -6dB ). At lOd. B per division it is possible t o display IOOdB if the graticule has 10 divis i ons tit is represents a volt age range of I 00,000 to I. By selecting the reference unit to dB-microvolt, the signals are represented with respect to I microvolt. Unlike a linear scale, where each increment represen t s a fixed difference between signallcvcls, each incre ment on a logarithmi c scale repre-

versus frequency, and to a c curately measure the peak signa l frequencies Thro u gh the use of markers, peaks can easily be identified and a numeric representation ofthe peak signal's frequency as well as amplitude is achieved This feature was use d extensively in obtaining tbe frequency and tnaJ(imum power level measurements described herein. Yet a nother feature of a spectnun analyzer is the ability to display amplitude variations of a single fre quency signa l versus time. By centering on a single carrier frequency and se l ecting "zero span", the analyzer in thi. s mode ean be, in some eases, b e used to he l p ascertain the frame rate of a particular lane's TDMA signal. D Summary of Eva l uation Findings Statistical Perfoanance Comparisons The ETC core battery" field perfonnance evaluations included run s at different speeds witb different orderings of the vehic les (con figurat i ons). N e itber the speed nor the conftgu rations appeared to have any 33 The number of photo opportunit ies was differ ent for each participant since it depen d ed on the number of invalid tran s ponders supplied by the p a rtic ipant. Figure 8 illustrates the percent of missing or bad photos for each participant. Electrical Measureme nts Based ot1tbe electrical measurements made, several general conclusions can be drawn. Table 5 gives a summary of the electrical verification measurements made by CUTR/ USF as part of the field performance evalua tions. As mentioned previously; d1e carrier frequency is an important parameter for an ETC system. Five FCC allowab .Ie bands have been i dentified for A VI/ETC operation as follows: 915 (+or 15) MHz, 2450 (+or 15) MHz, 5000 ( +or IS) MHz, 10,525 (+or 25) MHz, and 24, 1 25 ( + or SO) MHz. The participants, witb one exception, used carrier frequencies falling w i thin the fJrSt two FCC allowed bands. The Figure 7 influence in the occurrence of inval i d transac tions or in the occurrence of missing/bad photos Figure 7 illustrates the percent of invalid transac tions b oth including and excluding violation enfor c ement criteria, for tbe participants. Perce n t of I nvalid T ransactions b y Participan t


34 Figu r e 8 Percent of Missing o r Bad Photos By P arti cipant Ta ble 5 Summ a ry of E l ectrica l Measu r ement Results 08SERVAnONS Syltem I System 2 Systems Corr ia r F requenc ies 920 6 920 -921 A 903-911 0. 1 342 2A26 (MHZ ) E sttnoted Pe<>k Powe r 0 .049 4 It 3.5 0 062 @ 3.5 1 .5520 3 5 0 0475 0 0.01 0 .00560 1 (m i c roWotts/Sq. me ters met ers met ers meters mater em @ dlst-once) Frome Rote 0 6 2 5 1.2 1 3 3 n/o (m!cr

one exception is the 11 (Tiris I) system whose 134kHz signals were well below the FCC allocations for microwave A VI systems. Beyond FCC compliance, other factors to con sider with regard to carrier frequency choice are susceptibility to interference, and bit rate limitations. As illustrated in the spectrum ana lyzer plot in Figure 9, local interference was present in the Sunrise Toll Plaza's electromag netic environmen t at around 930 MHz, which was close enough in frequency to cause some problems for participants operating in the 915 ( + or 15) MHz FCC allowed band. In con trast, as seen in Figure 10, no such local interference signals appeared to be present around the 2450 (+or 15) MHz band. AI though the situati on may change in the future the 900 1000 MHz frequency range has be come very crowded with increased use of cellular telephones, pagers, utility meter readers, etc., operating in this range. In fair ness, participants were able to overcome the : REF .(IJ d8to PEAl< Figure 9 Carrier Frequency Plot (930 MHz) 930 MHz interference signals and obtain ETC read/write results with their systems. It should also be mentioned that 2450 MHz is also the frequency used in most microwave ovens Bit rate limitation imposed by frequency choice is primarily an issue with the inductive loop systems due to the low frequency used. With out entering a detailed discussion of modulation techniques, the maximum bit rate is a fraction of the carrier frequency, thus an inductive loop system, for example simply is not capable of 500 kbps bit rates handled quite easily by higher frequency carr ier schemes. In regard to the peak power measurement, it should b e emphasized that the li-ted numbers are considered a rough estimate" of the power levels detected at a specified distance from the transmitting antenna In all cases, the radiated power was too low to be detected on a RF hazard monitor. The power estimates listed are calculated from the spectrum analyzer ampli tude reading corrected for antenna and cable LOO loss. These are all seen to be well below the 3 milliWatts/cm2 (900 MHz) and 8 milliWatts/cm2 (2450 MHz) ANSI recomme. oded maximum power. It is clear from these results that, within the validity of this current safety standard, aU of the demonstrated microwave radiation levels are negligible. OB/ REF LEVEL 0 --i\k Fraq (MHz) 1 ezf." a ssa.-s 4 88".5 &TART .II v.t-lz -51,66 dBin -iM. QJB dBrn -31.77 d!kn -48.29 dBm RES BW MHZ Pi< P'req 6 7 8 9 VBW SQI" kHz The frame. rate tabulated indicates the minimum t ime required between data transmiss.ion on a give-n lane. (CUTR qualifies t!Us with the understanding that the listed value is subject to possible errors in


36 Figure 10 Carrier Frequency Plot (2.45 GHz) MKR 93iJ M H Z 7 6.83 dBjH ' I j_ -I ,, l ; b t -r-r' 1 MDrkcr Troce Type 1: {A) FreQ .2: (A) f"req F rtq I Ttm z.aas MHz 93f MHZ. AfltP 11 tude ?2.34 dB)H 76.83 dB).N 3; l noc:t1ve .a: Inactive STAAT MHZ RES BW 3." ..-.z VBW 1 MHZ. STOP 2 .921 GHZ #SWP 2.8f interpretation of the parti c ipant demonstration and the associated explanation.) Thus the maximum number of"handshakes possible as a vehicle passes through the Jane can be directly related to this number. The additional i nforms lion needed is the amount of time that the vehicle is within the communication area of the tran sa ction antenna This effective communica tion area is very difficu lt to asses s without an explicit, participan tassis t ed field measurement. It depends on the field of view of both the roadside antenna and the transponder antenna It also depends upon the transmit power and the receiver sen sitivity for both directions of communication flow. Since the measurement data set excludes sufficient information to accurately assess the length of the communi ca tion area for e acb participan t along the direction of vehicle travel the relationship to number of handshakes is illustrated with the following simp l e example. Example C alculation of Number of Handshake s: Assume the effective communication length along the direction of travel is 3 meters (chosen for illustration purposes only) the vehicle velocity is 20mph. and the frame rate is 5 micro-seconds The time that the vehicle is in the communi cation area t, is given by: t, = 2.236 x L, (meters) I v (mph) where L is the effective communication length, and v is the vehicle velocity in miles per hour. For the given example : t = 2.236 x 3/20 = 335 micro-seconds So, the maximum number of handshakes for a 5 micro -second frame period t/S given by:


N = lnteger(tjt) = lnteger(335 micro seconds I 5 micro-seconds) = 67 hond shakes The importance of determining the maximum number of "handshakes is the subject of some debate. Some of the participants claimed that they reliably read/write all the necessary information with only one ''handshake". Others only take additional "handshakes" in the event that an error is detected in the digital data received, or for other reasons, a bad read is detected Almost all participants stop commu nication between the roadside and the vehicle once a successful read has occurred. Consequently, multiple handshakes" during system operation appears to be the except i on, rather than the rule for effective ETC system opera tion. The fmal parameter to consider is the bit r ate. This parameter determines the rate at which information can be transferred to and from the roadside during an ETC transaction. Th. is translates to the minimum time required to transfer the necessary information to and from the roadside. For example, for a transponder with a fixed data frame of 128 bits and a variable data frame of 128 bits, a total of256 bits of information needs to be transferred. At a data rate of9. 6 kbps (i. e 9,600 bps), the minimum time required to transfer 256 bits is given by: t, = 256 bits 19,600 bits per second = 26.67 milfi .. seconds With a higher data rate (e.g., 500 kbps), the time to transfer the same number of bits be comes: t, = 256 bits/500,000 bits per second = 0.512 milli-seconds 37 Unfortunately it is difficult to make more exacting conclusions reg a rding the impact of bit rate on ETC performance based on the results of the current evaluation. However, it can be stated that the higher the b i t rate the greater the expected performance reliability under higher speeds (ETC express lanes), and the more compa tible with other IVHS applica tions (traffic management, traveler in formation systems, etc.) In summary, the field performance evaluations carried out allowed for some of the most rel ev a nt ETC e)ectdcal characteristics to be quantified and compared. The system imple mentations among the participants vary quite widely in terms of modulation techniques, COUlJUUilieation protocols antenna te c hnology and error control methods. Given the short time frame of evaluation, it was extremely difficult to draw specific re l ationships between the observed electrical and u l timate performance and reliabi l ity of a given ETC system. To be sure, the observed electri cal characteristics are linked to performance however, our experience suggests some caution in discounting a system bas ed on a single electrical characteristic, rather the characteristic in question must be c onsi dered within the context of the entire system operation, under a longer evalua tion period. Only then can a decision be made as to whether the characteris t i c i s truly a key limiting factor, or actually represents a parameter with a safety margin. VI O THE REVALUATION ISSUES A. H ea lt h a n d P erfo rm ance F ac tors During the course of the ETC field perfor mance evaluations, three areas of concerti arose related to ETC health and performance f actors.


J8 Recently, national news re lating to human health issues associated with exposure to elec tromagnetic fields (EMF) ha s captured wide spread attention. EMF is briefly discussed below as related to the ETC power density levels measured during the field performance evalu ations Metal oxide windshields, and potential a ttenuation problems associated with metal oxide windshields will also be ad dressed Finally, ETC carrier frequencies, as related to the issue of FCC frequency alloca tion, will be outlined. Both metal oxide wind shields and frequency allocation are issues which will affect th e performance and reliabil ity of ETC. This section of the report is in t ended only to provide background information regarding the three aforementioned ETC issues. Electromaenetjc Fields The issue of human health factors is an appro priate concern in the use and exposure to RF technology in electronic toll collection. Ques tions are continuously being raised concerning the safety of radio frequency electromagnetic fields generated by ETC equipment. The RF frequency bands in the radio and microv.'3ve spectrum utilized for ETC are 902-928 MHz or 2400.2500 MHz. For these bandwidths, several organizational standards for power density fields have been e.m.blished. For example, the American National Standards Institute standard (ANSI C95-1) is 3 milliWatts/sq.cm for 8 50-950 MHz, and 8 milliWatts/sq.cm. for 2400 -2 500 MHz. The U.S. Occupational Safety and Health Adminis tnuion standard (OSHA 1 910.97), and the International Electroteehnica l Commission standard (IEC 6570) is 10 milliWattslsq.cm. Actual power density measurements taken during the field perfonnance evaluations indicate a range of 47.5 nanoWanslsq.em. to 1.552 microWattsl sq.cm., below the national standa rds mentioned above for exposure levels. EMFs are commonplace, from the motors in refrigerators to the radiation from comp uter or television screen to the very slight emiss ions from e l ec tric blankets. EMFs arise whenever an electric curTent is passed through a wire. The greater the current, the higher the fields E MF s are silent, invisible waves that weaken with distance from their sourt:e. Most impor tantly, it must be pointed out that ETC is generally involved with radio tran smission, or higher type frequencies with no electric or magnetic fields. The lower frequencies of EMF so u rces mentioned above create the e lectric and magnetic fields that are causing all the concern. Severa l previous studies have shown that exposure to EMFs increa.

Table 6 Allocation of Broadcast Freq uenc ies GOVERNMENT NON-GOVERNMENT ALLOCATION (MHz) (MHz) FCC USE DESIGNATION 902 -9 28 902-928 Pur pose Mobile Rad i o loca tion US2157,(Arnat eur) 707 U$215 US218 US267 707 U$2 15 US2 18 US2 75 G11 G59 U$275 US116 US215 US268 G2 Fixed US116 US215 US268 928-932 929-932 932-935 Fixed US215 US268 G2 Land Mobile US116 US215 US268 Fixed US215US268 93!;.941 935 940 U$116 US215 US268 G2 land Mobile 941-944 F ixed US268 US301 US302 944-96 0 Aeronautical Radionavlgatlon 709 US224 960-12 15 U$116 US215 U$268 Mobile U$116 U$268 Fixed U$268 U$301 U$302 FIXed NG120 960 1215 Aeronautical Radionavigation 709 U$224 Private Land Mobile Private Operational Fixed M iaowav a Domestic Publ i c land Mobile Private Land Mobile Private L and Mobile Public Fixed Public Private Operational Fixed Microwave


40 Table 6 (Cont.) Code Definitions F=========================9 U$116 US2 15 US26S U$218 U $267 US275 U$301 U$302 G2 G11 no nGW ass i gnments are to be made t o Government radio stations after Ju l y, 1970, except on case-bycase bas is. emi ssions f or microwave ovens after 1 980 must be confined to 902 -928 MHz band. 928-942 MHz band is also allocated to radi olocat!on service for Government ship stations provided they don't i n tertere wit h non Government land mobile s tations. bands 902 MHz and 918 MHz are avai lable for Au toma ti c Ve h icle Monrtoring (A VM) Systems prov ided the systems don' t interfere with Government stations operating i n these bands. AVM Systems must tolerate any I n terference from the operation of i ndus trial, scientlfte, and medi cal (ISM) devices and operation of govern ment stations authorized in these bands prohibits ham radi o operation i n Colorado and Wyom i ng. band 902-928 MHz is allOcated on secondary basis to ham radio ptovlded they don' t interfere w ith AVI systems broadcast auxi l iary stations licensed as of 1984 o perating in band 942 944 MHz may continue on ooequal with other applications. ooncems allocations i n Puerto Rico. for bands MHz and 928 942 MHz Government radi o locatio n is limited to mili t ary setvices. government fixed and mobile radio services are permitted in band 902 928 MHz on a secondary basis G59 for band 902-928 MHz Governme-nt non-military ra d iolocation is secondary to military radio l ocation 707 band 902 928 MHz is designated f o r ISM applications 708 709 .... } :,;>:;.. ; ,.,_, bands 942-947 MHz and 952-960 MHz to mobi l e serv i ces is on a primary basis. band 960 MHz is reseNed g l obally for a i rborne e l ectronic aids l" ._. : ; . J;.. I ' i / : ;


diagram came from the Code of F ederal Regu l a ti o n s, Title 47, issued in 1 991. '!be codes used in Tnblo 6 ore also lrao slated. As indicated, according to FCC, A V I technolo gies are assign ed the 902-928 MHz band. Recently proposed rule changes for this band would, if adopted, segregate location and AVI services on different frequencies, broaden the range of services ve ndo rs coul d offer in this band, and possibly allow tw o or more l o cation services to share the same portion oftl1e band in the same market. The FCC believes interfer ence from ot her sources is possible, but impos sible to predict. Certainly it can be observed that this general bandwidth is becoming extremely crow ded such that a vendor o r operator can only wait for a problem to arise, then troubleshoot based on the frequency allocation illustration above. According to the January 1993 issue of the MIS America newsletter the FCC and the Nat i onal Telecommunications and Information Agency are considering four issues that nave poten tial impact on the availability of radio frequency spectrum essential for IVHS purposes. FiJSt, the FCC bas proposed to allocate II 0 MHz of spccuum between I.SS GHz and 1.99 GHz for personal communications ser vices in tbe United States. This spectrum allocation could provide an additional source of the RF link in IVHS applications. Second, the FCC has proposed to rewri t e its cx isti ng mles go v e nting Private Land Mobile Services and to re-allocate th. i s band below 512 MHz. These m l e c h anges could expand the capacity o f this bandwidth below 512 MHz by a l mos t 500 percent and create new channels for licensing over the next 10 years, enhancing the commer cial deployment of!VHS Third the FCC proposes to allocate the 2310-23 60 MH:t band for sate llite Digital Audio Radio Services (OARS) in the United States. Finally, the FCC has also proposed a U.S. allocation in accor-4 / dance with the international allocation assi .gned for OARS. This allocation should f.1cilitato jntc mationnl equipment compatibif.ity for U.S. auto makers. Because radio-frequency spectrum matters usuaUy involve ext e nsiv e amllysis as well as politica l negotiation, i t has become imperative for spectrum management issues ro receive coordinated attention fiom ali! V H S applications, including ETC, which is to be expanded to e l ectronic toll and traffic manage ment. Metal Oxide F ilm and Metal Qxjde Film Windshield s Glass containing metal oxide film weakens electromagnetic signal s passing through it. Interior transponders that were located just behind vehicle windshields during the ETC field perfonnance evaluations did n ot p rovide for reliable read/w r ite transactions. 'D1e Chevy Lumina van, was the only fleet veh icle with a metal oxide film windshield causing sufficient signal weakening (attenuation) to affect ETC transa ctions. P articipants who selected not to place their interio r trans p onder directly behind this windshield (all, except for AT&Twbich bad attenuotion prob l ems as well) were lbereby admitting the inability to reliably perfonn in this type of enviroom en .t. A metal oxide windshield contains a metal oxide film laminated between two pieces of gla ss 'D1e most common films consist of sil ver oxide, which i s vacuum sputt er-deposited (sprayed on 10 provide for a uniform film thick ness and consistency in seve r al layers unti18-12 mils tbick) Zinc or copper oxide coatings protcct tbe s ilver o x ide and prevent deteriora tion According to Southwall Technologies (Palo Alto Califo rnia) manufacturers of metal film, a m etal oxide windshield will attenuat e a 920


42 MHz signal20-30 dB, or a power reduction of 11100-1/1000 of the original interrogation signal (depending on the type o f metal oxide film). Even though this magniturde of reduc tion appears low, it still affected the reliability of valid transactions during trhe field perfor mance evaluations for the Chevy Lumina van. Further, there are four known manufacturers of metal film windshields: Troesch Autoglas AG (Switzerland); Libby-Owens-Ford (LOF) of DaytonToledo, Ohio; Pittsburgh Plate Glass (pPG) of Pittsburgh, PA; and Ford Glass (Carlite) of Detroit. Table 7 lists U.S. auto glass manufacturers, selected brand names, and vehicles each brand is installed on. The brands do not include tinted glass, which looks similar to metal oxide film glass. Three common brand names for tinted glass wer e found on the evaluation fleet vehicles; Solar Ray, Soft Ray, and Flo-Lite. Tinted glass is composed of materials that filter out light but have little or no effect on electro magnetic waves at A VI frequencies. Heated windshields contain metal oxide film and are mentioned as well. Industry experts estimate Table 7 Metal Film Windshield Characteristics fo

that about 2% of the U S. fleet of vehicles currently have metal oxide windshields (prob abl y higher for F lorida) but n o futuro trends on this issue could be obtained B. R eeom mendations tor Furtber Eval11atio n This very limited ev aluation of ETC technolo gies has provided an assessment of basic oper ating cbarac teristics a n d perfonnnnce reliabil ity. However, as time and budget co nstraints will allow several areas of further research and eva luati o n would be desitable ln no order of importance thes e areas would include: I. ETC operations fuUy integrated with hard ware and software of upgraded FOOT con ventional toll collection system, including (most importantl y) automatic vehicle c las sifi cation. 2. User preferences for ETC serv ice features (particularly transponder type and placemont ), and review and assessment of ETC user perception surveys from other toll agencies, particularly those with existing BTC patrons. 3 Extension of ETC evaluations beyond single toll plaza passage to encompass monitoring and v erification of points of entry and exi t along the turnpike, as well as traffic management character i st ic s such as speed, volume, density and incident detect i o n 4. Cost-effectiv eness of commercial fleet management along the turnpike system. 5 Effects of alternative pavement markings, advance signage, and speed contro l techniques to accommodate ETC. 6. Reliability and performance of automatic in lan e replenishment of ETC patron accounts. 7. Variable pricing of toll fares through ETC in order t o maximize turnpike and adjacent non-toll facility capacity during peak and non-peak travel times. This would include both increasing and decreasing tolls VI I CONC LUSIONS Based on the findings o f this evaluation, severa l very important conc lusions can be listed as follows: I. The total number of vehicle passes for this evaluation could not determine a statisti cally valid level of performance, however it did indicate that under CUTR's dofini tion of"valid transactions" which in eludes VES, all participants would have difficulty achieving advertised perfor mance levels (i.e., 99+%). CUTR believes this was primarily attributable to inad equate integration ofVES and BTC, not necessarily inadequate VES technology 2. Tota l "anomalies", which CUTR believes to be a good indicator of general readiness and preparedness for the rigors of this evaluatio n resulted in succe ss rates varyin g from a low of70.8% to a high of 98.2%. 3. Invalid transactions (or the absence of valid transactions) which CUTR believes to be the true indicato r of performance reliabi l ity within the environment of this evaluation, resulted in success rates varying from a low of 89.7% to a high of 98.4%.


4. Integrated violation enforcement capabili ties was a general weakness exhibited by all the participant s. The best participant perfonnanec resulted in 36% missing or bad photos All of rhe other participants had between 44% and 6 8 % of their photo opportunities resulting in missing or bad photos. S. Discounting for the general weakness exhibited by all the participants in the VES component criteria ofCUT R s definition of valid transaction, the modi fied indicator of perfonnance reliabi l ity would consequently indicate the lowest rate of sucecss t o be 90.2%, and the high est rate of success to be I 00"/o. 6 All participants were successfully able to demonstrate their specific opernting characteristics in the field, as indicated in writing prior to their respective field evaluations. However, more extensive evaluations need to be cond ucted to fur ther establish the relationship of these characteristics to performance capability and reliability Generally spe aking, i t can be speculated that given a higher carrier frequency, faster frnme rate, and higher bit rate ; more data can be transmitted with the greatest reliability and least likelihood of interference 7. The ability to consjsJcnt!y transmit through metal-oxide windshields was a problem for all the participants. Even though a relative small percentage of vehicles are equipped with these types of windshields, multiple transponde r mount ing locations (i n addition to behind the front windshield)should be provided t o rectify this situation. 8 During the "optiona l evaluations: "Shad owing" was not n problem in recognizing both vehicles; however photo s could not be produced for known violators, whether the leading o r trailin g vehicle Anti passback was achieved by all participants. Crosslane recognition was a problem for several participants. 9. Based on CUTR's direct experience w ith this ETC evaluation and inve s t i gation into examinations of ETC perfonncd by others, i t has become apparent that a nationally accepted, standardized field perfonnance test should be established to evalua te (and "pre-qualify") ETC industry vendors. A common and comprehensive basis for comparative performance evaluations., prior t o deployment, is needed with the rapid and continuous evoluti on o f ETC. Most importantly, consistent s tandardized results-ori ented information could be distributed throughout the toll industry. I 0 The FOOT Turnpike office s hould proceed with its procurement process: however chis report should serve as a general guide to weaknesses that apparently s till exist in the ETC industry. In structuring its perfor mance specifica tion FOOT should allow for Oexibility in operating characteristics and sufficient time for perfonnance acceptanc e testing.


CUTR Project Contacts: Chester Chandler, P.E. ETTM Project Manager Florida Department of TransportationOffice of Florida's Turnpike 1211 Governor's Squ a r e Blvd., S uite 100 TaUaha ssee, Fl orida 3230i Tel: ( 904 ) 488 4671 Fax: ( 904) 48 7 -4340 Michael Pie trzyk P .E. Senior Research Associate and IVHS Program Manager Center for Urban Transportation Research College of Engineering-Un iv e r s ity of South Florida 4202 E. Fowler Avenue, ENG 118 Tampa, Florida 33620-5350 Tel: (813) 974 -3 120 Fax: ( 813) 9 7 4 5168


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