HOME WEB NEWS IMAGES CLASSIFIEDS YELLOW PAGESPOLLS - SURVEYS WIKI COUNTRIES PHOTOS US UK INDIA
Cities Stocks Weather Movies Coupons Travel Blogs Health Horoscope Maps ASIA EUROPE Classifieds Yellow Pages
|
The term intelligent transportation system refers to efforts to add information and communications technology to transport infrastructure and vehicles in an effort to manage factors that typically are at odds with each other, such as vehicles, loads, and routes to improve safety and reduce vehicle wear, transportation times and fuel consumption.
Contents |
Interest in ITS comes from the problems caused by traffic congestion worldwide and a synergy of new information technologies for simulation, real-time control and communications networks. Traffic congestion has been increasing world-wide as a result of increased motorization, urbanization, population growth and changes in population density. Congestion reduces efficiency of transportation infrastructure and increases travel time, air pollution and fuel consumption.
The United States, for example, saw large increases in both motorization and urbanization starting in the 1920s that led to migration of the population from the sparsely populated rural areas and the densely packed urban areas into suburbs. The industrial economy replaced the agricultural economy leading the population to move from rural locations into urban centers. At the same time, motorization was causing cities to expand because motorized transportation could not support the population density that the existing mass transit systems could support. Suburbs provided a reasonable compromise between population density and access to a wide variety of employment, goods and services that were available in the more densely populated urban centers. Further, suburban infrastructure can be built quickly, supporting a rapid transition from a rural/agricultural economy to an industrial/urban economy.
Recent governmental activity in the area of ITS – specifically in the United States – is further motivated by the perceived need for homeland security. Many of the ITS systems proposed also involve surveillance of the roadways, which is a priority of homeland security.Monahan, Torin. 2007. "War Rooms" of the Street: Surveillance Practices in Transportation Control Centers. The Communication Review 10 (4): 367-389. Funding of many systems comes either directly through homeland security organizations or comes with their approval. Further, ITS can play a role in the rapid mass evacuation of people in urban centers after mass casualty events or as a result of a natural disaster or threat. Much of the infrastructure and planning involved with ITS parallels that needed for homeland security.
In the developing world, the migration of people from rural to urbanized habitats has progressed differently. Many areas of the developing world have urbanized without significant motorization and the formation of suburbs. In areas like Santiago, Chile, a high population density is supported by a multimodal system of walking, bicycle transportation, motorcycles, buses and trains. A small portion of the population can afford automobiles, but the automobiles greatly increase the congestion in these multimodal transportation systems. They also produce a considerable amount of air pollution, pose a significant safety risk and exacerbate feelings of inequities in the society.
Other parts of the developing world such as China remain largely rural, but are rapidly urbanizing and industrializing. In these areas a motorized infrastructure is being developed alongside motorization of the population. Great disparity of wealth means that only a fraction of the population can motorize, and therefore the highly dense multimodal transportation system for the poor is cross-cut by the highly motorized transportation system for the rich. In these areas the urban infrastructure is being rapidly developed, providing an opportunity for building new systems incorporating ITS from the beginning.
Intelligent transportation systems vary in technologies applied, from basic management systems such as car navigation, traffic signal control systems, container management systems, variable message signs, automatic number plate recognition or speed cameras to monitoring applications such as security CCTV systems, and then to more advanced applications which integrate live data and feedback from a number of other sources, such as parking guidance and information systems, weather information, bridge de-icing systems, and the like. Additionally, predictive techniques are being developed, to allow advanced modeling and comparison with historical baseline data. Some of the constituent technologies typically implemented in ITS are described in the following sections.
Various forms of wireless communications technologies have been proposed for intelligent transportation systems. Short-range communications (less than 500 yards) can be accomplished using IEEE 802.11 protocols, specifically WAVE or the Dedicated Short Range Communications standard being promoted by the Intelligent Transportation Society of America and the United States Department of Transportation. Theoretically the range of these protocols can be extended using Mobile ad-hoc networks or Mesh networking.
Longer range communications have been proposed using infrastructure networks such as WiMAX (IEEE 802.16), Global System for Mobile Communications (GSM) or 3G. Long-range communications using these methods are well established, but, unlike the short-range protocols, these methods require extensive and very expensive infrastructure deployment. There is lack of consensus as to what business model should support this infrastructure.
Recent advances in vehicle electronics have led to a move toward fewer, more capable computer processors on a vehicle. A typical vehicle in the early 2000s would have between 20 and 100 individual networked microcontroller/Programmable logic controller modules with non-real-time operating systems. The current trend is toward fewer more costly microprocessor modules with hardware memory management and Real-Time Operating Systems. The new embedded system platforms allow for more sophisticated software applications to be implemented, including model-based process control, artificial intelligence and ubiquitous computing. Perhaps the most important of these for Intelligent Transportation Systems is artificial intelligence.
Virtually every car contains one or more mobile phones. These mobile phones routinely transmit their location information to the network – even when no voice connection is established. These cellular phones in cars are used as anonymous traffic probes. As the car moves, so does the signal of the mobile phone. By measuring and analyzing triangulation network data – in an anonymized format – the data is converted into accurate traffic flow information. The more congestion, the more cars, the more phones and thus more probes. In metropolitan areas the distance between antennas is shorter and, thus, accuracy increases. No infrastructure need be built along the road – only the mobile phone network is leveraged. Floating car data technology provides great advantages over existing methods of traffic measurement:
State-of-the-art sensor technologies have greatly enhanced the technical capabilities and safety benefits awaiting Intelligent transportation systems around the world. Sensing systems for ITS can be either infrastructure based or vehicle based systems, or both – see, for example, Intelligent vehicle technologies. Infrastructure sensors are devices that are installed or embedded on the road, or surrounding the road (buildings, posts, and signs for example). These sensing technologies may be installed during preventive road construction maintenance or by sensor injection machinery for rapid deployment of road in-ground sensors. While vehicle sensors are those devices installed on the road – such as in automatic number plate recognition – or in the vehicle, new technology development has also enabled cellular phones to become anonymous traffic probes, such as floating car data.
Inductive loops can be placed in a roadbed to detect vehicles as they pass over the loop by measuring the vehicle\'s magnetic field. The simplest detectors simply count the number of vehicles during a unit of time (typically 60 seconds in the United States) that pass over the loop, while more sophisticated sensors estimate the speed, length and weight of vehicles and the distance between them. Loops can be placed in a single lane or across multiple lanes, and they work with very slow or stopped vehicles as well as vehicles moving at high-speed.
Traffic flow measurement and automatic incident detection using video cameras is another form of vehicle detection. Since video detection systems such as those used in automatic number plate recognition do not involve installing any components directly into the road surface or roadbed, this type of system is known as a "non-intrusive" method of traffic detection. Video from black-and-white or color cameras is fed into processors that analyze the changing characteristics of the video image as vehicles pass. The cameras are typically mounted on poles or structures above or adjacent to the roadway. Most video detection systems require some initial configuration to "teach" the processor the baseline background image. This usually involves inputting known measurements such as the distance between lane lines or the height of the camera above the roadway. A single video detection processor can detect traffic simultaneously from one to eight cameras, depending on the brand and model. The typical output from a video detection system is lane-by-lane vehicle speeds, counts and lane occupancy readings. Some systems provide additional outputs including gap, headway, stopped-vehicle detection and wrong-way vehicle alarms.
Electronic toll collection (ETC) makes it possible for vehicles to drive through toll gates at traffic speed, reducing congestion at toll plazas and automating toll collection. Originally ETC systems were used to automate toll collection, but more recent innovations have used ETC to enforce congestion pricing through cordon zones in city centers and ETC lanes.
Until recent years most ETC systems were based on using radio devices in vehicles that would use proprietary protocols to identify a vehicle as it passed under a gantry over the roadway. More recently there has been a move to standardize ETC protocols around the Dedicated Short Range Communications protocol that has been promoted for vehicle safety by the Intelligent Transportation Society of America, ERTICO and ITS Japan.
Whilst communication frequencies and standards do differ around the world there has been a broad push toward vehicle infrastructure integration around the 5.9GHz frequency (802.11.x WAVE).
ITS Australia also facilitated via its National Electronic Tolling Committee representing all jurisdictions and toll road operators interoperability of toll tags in Australia for the multi lane free flow tolls roads.
Other systems that have been used include barcode stickers, license plate recognition, infrared communication systems and Radio Frequency Identification Tags (see M6 Toll tag).
The in-vehicle eCall is an emergency call generated either manually by the vehicle occupants or automatically via activation of in-vehicle sensors after an accident. When activated, the in-vehicle eCall device will establish an emergency call carrying both voice and data directly to the nearest emergency point (normally the nearest 112 Public Safety Answering Point, PSAP). The voice call enables the vehicle occupant to communicate with the trained eCall operator. At the same time, a minimum set of data will be sent to the eCall operator receiving the voice call.
The minimum set of data contains information about the incident, including time, precise location, the direction the vehicle was travelling and vehicle identification. The pan-European eCall aims to be operative for all new type-approved vehicles as a standard option. Depending on the manufacturer of the eCall system, it could be mobile phone based (Bluetooth connection to an in-vehicle interface), an integrated eCall device, or a functionality of a broader system like navigation, Telematics device, tolling device. eCall is expected to be offered at the end of 2010, at the earliest, pending standardisation by the European Telecommunication Standardization Institute and commitment from large EU member states like France and the United Kingdom.
Cordon zones have been implemented in Singapore, Stockholm and London where a special fee is collected (see Congestion pricing) from vehicles entering a congested city center. This fee or toll is charged automatically using electronic toll collection or automatic number plate recognition, since stopping the users at conventional toll booths would cause long queues, long delays and even gridlock.
Cooperation on road includes car-to-car, car-to-infrastructure, and vice versa. Data which is available at the vehicle is acquired and transmitted to a server for central fusion and processing. This data can be used to detect events such as rain (wiper activity) and congestion (frequent breaking activities). Cooperative systems will support the driver at his driving tasks. The system will be based on a wireless data transmission network. The server processes a driving recommendation dedicated to a single or a specific group of drivers and transmits it wireless and directly to the vehicle. The goal of cooperative systems is to utilise and plan communication and sensor infrastructure to increase road safety. The definition of cooperative systems in road traffic is according to the European Commission:3rd eSafety Forum, 25 March 2004
This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia
