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Page vi
Suggested Citation:"Summary." Transportation Research Board. 1996. Communication Mediums for Signal, ITS, and Freeway Surveillance Systems: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6338.
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Page vii
Suggested Citation:"Summary." Transportation Research Board. 1996. Communication Mediums for Signal, ITS, and Freeway Surveillance Systems: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6338.
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Page viii
Suggested Citation:"Summary." Transportation Research Board. 1996. Communication Mediums for Signal, ITS, and Freeway Surveillance Systems: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6338.
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SUMMARY The communications industry is rapidly evolving within the United States and the world. The material and installation costs of fiber optic cable are now comparable to twisted wire pair cable costs with significant bandwidth advantages. Wireless technologies (including spread spectrum radio, cellular/PCS, and microwave) do not have the bandwidth of fiber optic cable but can offer significant advantages in installation cost and time. The following are some of the important trends emerging in the communication industry: · Single-mode fiber optic cable has achieved parity with copper twisted wire pair cable in cost and _~¢ ~ r is less expensive than multi-mode fiber optic cable. Fiber optic terminals are still more expensive than twisted wire terminals (e.g., modems) and single-mode terminals are more expensive than multi-mode terminals; however, the cost difference is narrowing rapidly. · SONET (Synchronous Optical Network) fiber terminals, based on open standards, are emerging and becoming very cost effective. These provide bit rates from 5 ~ Mbps to over 10 Gbps. They also provide cost-effective add/drop capabilities for lower bit rate payloads (e.g., DS-3 from a SONET OC-n). In addition to fiber optic media, the SONET standards support wireless microwave to OC-3 (155 Mbps). The cost of wireless terminals is decreasing. The Federal Communications Commission (FCC) is making and considering rule changes that focus on opening new spectrum at higher frequencies and improving utilization at lower frequencies. Wireline modems are achieving 28,800 bps speeds over dialup circuits. In support of commercial T! services and video-on-demand, higher speed bit rates from I.5 to more than 6.2 Mbps are becoming cost-effective over twisted wire pair cable. Communication standards to support and promote multi-vendor interoperability are an important element of modern communication system design. Usually equipment designed to comply with standards is the most cost effective. Standards are readily available for bit rates ranging from RS 232 up to 38.4 bps, the digital hierarchy (DS-0 at 64 kbps to DS-3 at 145 Mbps), and SONET (OC-! at 51 Mbps to OC-192 at 9,953 Mbps). These standards support wire, wireless, and fiber mediums although bit rates supported varies. Communication equipment are evolving from cabinets to boards to assembliesiboxes as a result of continuing semiconductor advances and greater integration. This significantly increases equipment reliability with mean time between failure, which historically ranged from 5,000 to 20,000 hours, now ranging from 40,000 to 100,000 hours. Increasingly, manufacturers include self-test and redundancy features. Repair is accomplished by replacing the complete assembly or box and returning it to the manufacturer for replacement or repair. Manufacturer warranties can cover multiple years and can often be extended for costs usually at or below ~ percent of the equipment purchase price per year. Intelligent transportation systems (ITS) typically have communication subsystem costs of approximately 50 percent. Thus, communication subsystem design and operations are important considerations. Modern communication offers many benefits for implementation of ITS that include: Open standards that support multivendor interoperability. Integrated support for redundant configuration including hot stand-by that greatly reduces cost of extended-hour maintenance staffing. Although initial deployment costs might be higher, life- cycle costs are usually less. Emerging network management for computer-aided support of system monitoring and operations. Pending and actual failures are often detected by the system. Emerging range of equipment suppliers providing wireless, wire, and fiber products that are well suited for ITS communication infrastructure applications. Availability of communication experts/personnel to support the design, deployment and operation of ITS communication infrastructure. High reliability, system redundancy, and network management creates a very favorable environment to support cost-effective ITS implementation and operations. Local test equipment requirements for maintenance are modest. Modern network management allows jurisdictional staff to maintain the

communication system after modest training programs. With increased reliability and redundancy, availability goals usually can be achieved with normal 40-hour/week maintenance staff work schedules. In general, lower speed standards are not as widely or consistently embraced by industry and these are often supplemented by agency standards such as NTCIP. While wireless technologies lack the bandwidth of fiber-optic cable, it is the only medium suitable for vehicle/infrastructure communications. ITS stakeholders need to organize and actively engage the FCC to ensure that ITS wireless needs are adequately and appropriately addressed. Communication equipment suppliers desiring to enter the ITS market often become frustrated because their traditional marketing and sales staffs do not have experience in this unique market. The ITS market is very fragmented, consisting of the Federal DOT, 50 different state DOTs, and thousands of local jurisdictions and interacting agencies. The specifications, requirements, regulations, and procurement processes used by these organizations are usually not consistent. Decision makers can be difficult to identify and engage. While each organization has unique requirements that should be appropriately addressed, uniqueness for 'pride of authorship" or lack of common understandings should be minimized to encourage economies of scale. As part of ongoing ITS architectural activities, standards developments, and deployments, the ITS community needs to educate these suppliers on ITS requirements and to promote reasonable opportunities for ITS participation. While ITS is an attractive market, these communication suppliers normally address a more general market that ITS must learn to leverage. The ITS community needs to promote a supplier-fiiendly "ITS marketing" atmosphere toward the communication community.

Contributing Organizations The NCHRP project definition envisioned that most of the source material for this study would be obtained through a literature survey. We did, in fact, obtain significant material from the literature; however, communication technology is advancing and evolving so rapidly that we did not find the literature sufficient. Suppliers of communication equipment provided valuable information on costs, capabilities, performance, standards, and trends. Several suppliers recognized the ITS market potential and contributed information that addressed their industry segment products, capabilities, significant considerations, and trends. Other suppliers critiqued our information, usually thorough several iterations. Many suppliers provided data sheets, application notes, and other material that greatly helped the project. Several ITS equipment suppliers provided sections of this report. We asked that each wear his or her "technical hat" (as opposed to "sales hat") to describe technical features and benefits of the products they supply for ITS applications. We are very pleased with the professional contributions by these organizations. The sections contributed are listed below with company name, address, phone number, and a contact person. Several organizations did not provide actual written reports, but contnbuted significant time and effort providing information or reviewing our wnteups. These organizations are also listed below. Kimiey-Horn and Associates, Inc., and the principal investigators, wish to thank these organizations for their contributions and for the opportunity for professional exchange. We wish we could have spent more time with each contributor and that we could have expanded the slate of participants, but time would not permit. Section A.1.2.1 Fiber Cable Plants Siecor Corporation Contact: David Kiel 489 Siecor Park - ES P.O. Box 489 Hickory,NC 28603-0489 704/327-5511 Section A.1.7.2 Satellite Communications Comsat Laboratories Contact: Ajit Shenoy 22300 Comsat Drive CIarksburg, MD 20871 301/428-4090 Section A.1.2.2 Low-End Fiber Optic Transmission Systems for ITS Applications Math Associates Contact: Bruce Berman 5500 New Horizons BIv4. Amityville,NY 11701-1130 516/226-8950 Section A.1.4 Computer Considerations in Communication Matrix Corporation Contact: Laurent Meilleur 1203 New Hope Road Raleigh,NC 27610 919/231-8000 Section A.1.7.3 Broadcast Subcarriers for ITS Modulation Sciences, Inc. Contact: Eric Small 12A WorId's Fair Drive Somerset, N] 08873 908/302-3090 Substantial Information and Review of Section A.1.3.3 Microwave Point-to-Point Wireless Harris Farinon Canada Contact: Densi Couillard 3 Hotel de Ville, Doliard-des-Ormeaux Ormeaus Quebec, Canada H9B 3G4 514/421-8400 Review of final draft, Section A.4 Communication System Support Sandia National Laboratories, MS 0746 Contact: Laura Painton Albuquerque, NM 87185 505/844-8093

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