ADOT  (Arizona Department of Transportation) No defintion. ADT  (Average Daily Traffic) The total volume of traffic during a given time period, in whole days greater than one day and less than one year, divided by the number of days in that time period. ATIS  (Advanced Traveler Information Systems) Systems, which disseminate information to the traveling public over a variety of methods such as variable-message sign, kiosks, Internet, cable television, personal hand-held devices, etc. ATMS  (Advanced Traffic Management Systems) Systems, which collect, utilize, and disseminate real-time data on congestion on arterial streets and expressways, and will alert motorists of alternate routes. Components of an ATMS include CCTV monitoring, ramp metering, traffic signal control, vehicle detection, and communications. AVI  (Automatic Vehicle Identification) AVI systems permit individual vehicles to be uniquely identified as they pass though a detection area. A roadside communications unit broadcasts an interrogation signal from its antenna. When an AVI-equipped vehicle comes within range of the antenna, a transponder (or tag) in the vehicle returns that vehicle's identification number to the roadside unit. The information is then transmitted to a central computer where it is processed. The most common application of AVI technology is for automatically collecting tolls on tollways. AVL  (Automatic Vehicle Location) AVL systems enable the approximate location of a vehicle to be determined and tracked as it traverses the transportation network. The most common application of AVL technology is for dispatching emergency vehicles, tracking transit vehicles and providing passengers with arrival time estimations through information displays, and delivery companies. AZTech The AZTech Intelligent Transportation Systems (ITS) Model Deployment Initiative (MDI) is a seven-year project (two years implementation and five years operation) to develop an integrated ITS for the Phoenix metropolitan area. The goals of AZTech are to decrease travel time and enhance traveler mobility, resulting in safer and more efficient freeway and arterial networks for the traveling public. Bandwidth Measure of information-carrying capacity of a circuit. In analog systems, bandwidth refers to the total available frequency measured in Hertz (Hz), while in digital systems, bandwidth refers to the number of binary data bits transmitted per second (bps). CADS  (Computer-Aided Dispatch Systems) An "intelligent" interactive mapping and data entry system to dispatch, monitor, and manage emergency services. The emergency-dispatching hub uses a database and configuration tools in which an agency can store, use, and report on information such as incident histories, unit activities, etc., in a way that is logical and useful to the dispatcher and administrator. Capacity The maximum number of vehicles that can pass over a given section of a lane or roadway in one direction (or in both directions for a multi-lane highway) during a given time period (normally one hour, unless otherwise specified) under prevailing roadway and traffic conditions. CCTV  (Closed-Circuit Television) A system, which uses video cameras to provide visual surveillance of the freeway system. Character Any of the symbols, which may include the decimal digits 0 through 9, the letters A through Z, punctuation marks, operation symbols, and any other single symbols that a computer may read, store, or write. Closed-Loop System A system in which the computer controls an external process using information received from the process-e.g., the closed loop in a traffic signal control system is from the computer to the controllers affecting the vehicular traffic and sensed by the traffic detectors and this information sent to the computer. Codec  (Coder-decoder) Equipment, which transmits and receives coded video information. Coding compresses the video information so that it may be transmitted over a digital channel with a lower bandwidth than would otherwise be required to carry the information. Communications A system for communicating information from one location to another. Communications Hub A location at which data is transferred between backbone and distribution communications systems. Communications Medium The composition of the path along which a communications signal is propagated, such as twisted-pair cable, fiber-optic cable, microwave, etc. Conduit A cylindrical structure, usually of steel or polyvinyl chloride (PVC), which provides protection for communications cable. Congestion A freeway condition where traffic demand exceeds roadway capacity. Console A device used for communication between the operator and the computer. The operator's console deals with operations and usually includes display panels, printer, and computer. Cookie Technology A cookie is a message given to a Web browser (such as Netscape or Explorer) by a Web server. The purpose of cookies is to identify Web site users/visitors and possibly prepare customized Web pages for them. CVISN  (Commercial Vehicle Information Systems and Networks) CVISN is envisioned to link existing disparate and cumbersome information systems and databases (currently used by regulators to obtain compliance information) and enable the electronic exchange of information. CVISN consists of four components safety information exchange, credentials administration, electronic screening, and freight and fleet management. CVO  (Commercial Vehicle Operations) Systems, which enhance the communications between motor carriers and regulatory agencies, particularly during interstate freight movements. The components of CVO include Credential Administration, Safety Assurance, Electronic Screening, Carrier Operations & Fleet Management, and Security Operations. Demand The need for service-e.g., the number of drivers wanting to use their vehicles on a given segment of roadway for a specified unit of time. Detection The process of identifying the presence or passage of a vehicle at a specific point or the presence of one or more vehicles in a specific area. Detection Zone That area of the roadway within which a vehicle will be detected by a vehicle detector. Detector A device for sensing vehicles and collecting traffic data. A detector may be embedded in the roadway pavement (e.g., inductive loop detector) or placed above the roadway (e.g., passive acoustic detector). DOT  (Department of Transportation) No defintion. DPS  (Department of Public Safety) No defintion. Dynamic-Message Sign  (DMS) A sign that uses electronics or mechanics to vary the visual word, number, or symbolic display as traffic conditions warrant. The term is used interchangeably with variable-message sign and changeable-message sign. Emergency Management Systems Systems for managing emergency situations, which include Hazardous Materials Management, Emergency Medical Services, and Response & Recovery. Fiber A thin filament of glass, consisting of a core and a cladding that is capable of carrying information in the form of light. Fiber Optics Techniques for the transmission of light from a transmitting source through a bundle of tiny and flexible glass fibers. Firmware Logic circuits in read-only memory (ROM) that may be altered by the software as desired. FMS  (Freeway Management System) Real-time control, guidance, warning, and management of traffic in order to improve flow of people and goods safely and efficiently. Freeway Management Control, guidance, and warning of traffic in order to improve flow of people and goods safely and efficiently, using predetermined goals and objectives, including those related to impacts on and the influence of surrounding. Frequency The number of oscillations of a signal per unit of time-usually expressed in cycles per second (cps) or Hertz (Hz). Frequency Division Multiplexing  (FDM) A type of multiplexing in which the total channel bandwidth is divided into a series of subchannels, each of which occupies a subband of frequencies. GIS  (Geographic Information System) A computerized data management system designed to capture, store, retrieve, analyze, and report geographic and demographic information. GPS  (Global Positioning System) A government-owned system of 24 earth-orbiting satellites that transmit data to ground-based receivers. GPS provides extremely accurate latitude and longitude ground position coordinates; however, for U.S. strategic defense reasons, deliberate error (called selective availability) is introduced into the code that is provided for civilian users. HCRS  (Highway Condition Reporting System) An ADOT-developed application software, which provides continuous updates on roadway conditions by authorized clients. The information resides on a server and automatically feeds to other systems such as Internet and 511. High-Occupancy Vehicle  (HOV) A motor vehicle carrying at least two occupants, including the driver. An HOV could be a transit bus, vanpool, carpool, or any other vehicle that meets the minimum occupancy requirements, usually expressed as either two or more, three or more, etc., persons per vehicle. Highway Advisory Radio  (HAR) A low-powered radio (generally AM) station devoted to presenting travel-related information to the public. Incident A non-recurring event that causes reduction of roadway capacity or increase in demand. Examples of incident include accident, stalled vehicle, adverse weather, bridge or roadway collapse, spilled load, maintenance activities, construction, and special events. Incident Management Systems Systems for managing incidents, which include Surveillance & Detection, Verification, Mobilization & Response, Information Dissemination, and Clearance & Recovery. Installation All actions required to provide a properly functioning system, including construction, inspection, testing, debugging, and acceptance. Interface Connections between systems or subsystems. Interoperability The ability of systems to provide services and accept services from other systems, and to use the services so exchanged to enable them to operate effectively together. IP  (Internet Protocol) Routes data between hosts on the Internet and allows computers to communicate. ITI  (Intelligent Transportation Infrastructure) A communications information system that will integrate traffic, transit, and emergency service components already in place in cities and rural communities. ITS  (Intelligent Transportation Systems) The application of technologies in surface transportation to save lives, time, and money, and improve the quality of life. Some examples of ITS are ramp metering, variable-message signs, closed-circuit television monitoring system, and traffic signal systems. IVI  (Intelligent Vehicle Initiative) AVI is envisioned to accelerate the development and availability of advanced safety and information systems applied to all types of vehicles. Its primary goal is to help drivers operate vehicles more safely and effectively. AVI covers applications for passenger vehicles, commercial trucks, buses, and specialized vehicles such as emergency response, law enforcement, and highway maintenance vehicles. This initiative seeks to bring together public and private stakeholders to ensure that in-vehicle systems are technologically, socially, institutionally, and economically viable. Kiosk Computer monitor display located in a public area such as shopping center, airport, hotel, highway rest stop, or office complex, giving real-time traffic information for the purpose of trip or route planning. Kiosk may also provide information on services, facilities, and the like. Lane A standard width of roadway proportioned to permit a single vehicle safe passage. Lane-Control Signal  (LCS) A traffic control signal that is erected to control the direction of vehicular traffic movement in an individual lane. Level of Service A transportation-related term that describes the operating conditions a driver will experience while traveling on a particular street of highway. Loop Detector  (Embedded Detector) A detector that senses a change in inductance of its inductive loop sensor caused by the passage or presence of a vehicle near the sensor. Management The allocation of necessary resources for the proper functioning of the system. MMF  (Multi-Mode Fiber) An optical fiber that that has larger-diameter inner core and supports more than one propagating mode. Multi-mode fiber is designed to support relatively low-speed transmission over relatively short distances. Mode A particular form of travel (i.e., walking, bicycling, traveling by bus, traveling by carpool, traveling by train, etc.) Modem  (Modulator-Demodulator) A device used at both ends of a communications path to transmit and receive data. Multiplexing The process of combining two or more communications paths into one path. Node A location at which data is transferred between backbone and distribution communications systems. See Communications Hub. NTCIP  (National Transportation Communications for ITS Protocol) A new data communications protocol that allows computers, master controllers, and field devices to communicate with each other, regardless of the type of device or manufacturer. NWS  (National Weather Service) No defintion. Occupancy The percentage of roadway length occupied by vehicles at an instant in time. In general use, it is a measurement based upon the ration of vehicle presence time (as indicated by a presence detector) over a fixed period of total time. Operating Speed The highest overall speed, exclusive of stops, at which a driver can travel on a given highway under prevailing conditions without at any time exceeding the design speed. Operations All actions necessary for the proper functioning of a system, such as information gathering, synthesis, and dissemination to equipment, other agencies, and the traveling public, including those previously associated with response, preventive, and design modification maintenance. Park-and-Ride Lot A facility, which serves as a transfer terminal for automobiles and bikes, and which is normally served by public transportation. It can include spaces used by persons transferring to carpools or vanpools whether officially designated for that purpose or not. Peak-Hour Traffic The highest number of vehicles passing over a section of a lane or a roadway during 60 minutes (consecutive). Peak Hour That hour during which the maximum amount of travel occurs. It may be specified as the morning peak hour or the afternoon peak hour. Peak Period The period during which traffic levels rise from their normal background levels to maximum levels. These periods are for morning, evening, and mid-day peaks and include the appropriate peak hours. Preferential Treatment In transportation, giving special privileges to a specific mode or modes of transportation (e.g., bus lanes or signal presentation at intersections). Project Any effort having scope, schedule, budget, and desired outcome, satisfactory to the customer. Protocol A set of codes, procedures, and elative timing relationships by which data are transmitted over a communications channel, such as a twisted-pair, fiber optic, etc. Queue A line of waiting vehicles or persons-e.g., traffic at a bottleneck location or signal, or buses at a park-and-ride facility, or persons in line to board a bus. Ramp Meter By pass A form of preferential treatment in which bypass lanes are provided at a ramp meter for the exclusive use of high-occupancy vehicles. Ramp Metering A system used to reduce congestion on a freeway facility by managing flow from on-ramps. An approach ramp is equipped with a metering device or a traffic signal that allow the vehicles to enter a facility at a controlled rate. RBDS  (Radio Broadcast Data System) RBDS is a method of communication with the traveler, whereby real-time, relevant, and accurate information is provided to the drivers. Digitally coded traffic information will be broadcast via a local FM radio station, along with the normal audio signal, on a subcarrier frequency. The information is coded in International Traveler Information Interchange Standards (ITIS), which is a standard protocol for coding locations and traveler-related events. RBDS receivers then take the subcarrier information and display it in one of several formats. The information may be shown as graphics on an in-vehicle navigation system, as text on a small LCD screen, or broadcast as an audio message, depending on the type of receive Recurring Congestion Predictable congestion, which occurs at locations where demand exceeds capacity, or at geometric bottlenecks (e.g., lane drops, high-volume entrance ramps, etc.) RWIS  (Road Weather Information System) A system consisting of meteorological components strategically located alongside the highway, which allow the owner to make more informed decision during winter storms. Specialized equipment and computer programs monitor air and pavement temperature to make forecasts regarding how the winter storms impact the highways. The principal components of RWIS include pavement sensors, atmospheric sensors, remote processing unit (RPU), and central processing unit (CPU). Signal Preemption A technique for altering the sequence or duration of traffic signal phasing using vehicle detection in order to provide preferential treatment for buses and emergency vehicles. SMF  (Single-Mode Fiber) An optical fiber that has a thinner inner core and supports only one mode of light propagation. Single-mode fiber performs better than multi-mode fiber over longer distances at higher transmission rates. SONET  (Synchronous Optical Network) A fiber-based system used to increase throughput and bandwidth of data transmission through a set of standard multiplexing parameters. The base level of a SONET signal is at 51.84 million bits per second, which is a DS-3 with extra overhead for maintenance and diagnostics capabilities. Each SONET level is called optical carrier (OC); hence the base level is OC-1, with increments increasing to OC-192. Surveillance A process of observing traffic performance through the use of detectors. System A group of related and integrated components organized to accomplish a specific set of functions. Systems Engineering A process whereby a set of required functions are analyzed, defined, and allocated to portions of the system. Systems Integration Combination and coordination of separate and diverse systems into a more complete or harmonious whole that will work together. Systems Management The act of directing, coordinating, and/or controlling the design and implementation phases of a system. T1 Line A special type of telephone line for digital communications, with a maximum data rate of 1.544 million bits per second. TMC  (Traffic Management Center) A central facility that controls, monitors, and manages the surface transportation system within its coverage area. See also TOC TOC  (Traffic Operations Center) A central facility that controls, monitors, and manages the surface transportation system within its coverage area. See also TMC. Traffic Management System  (TMS) Any measure to improve the operations of a facility without construction of additional roadway lanes. Examples of TMS include Dynamic Message Signs (DMS), ramp metering, and closed-circuit television (CCTV) camera surveillance, and vehicle detection. Twisted-Pair Cable A twisted-pair involves two solid copper wires, each covered with a plastic insulator and twisted together. Variable-Message Sign  (VMS) A sign that uses electronics or mechanics to vary the visual word, number, or symbolic display as traffic conditions warrant. The term is used interchangeably with variable-message sign and changeable-message sign. See Dynamic-Message Sign (DMS). VMT  (Vehicle Miles of Travel) No defintion. Volume Number of vehicles passing a given point over a period of time.