The goal of VII is to establish a communication link between vehicles (via On-Board Equipment, or OBE) and roadside infrastructure (via Roadside Equipment, or RSE) to enhance the safety, efficiency, and convenience of transportation systems. Two potential approaches are the widespread deployment of a
dedicated short-range communications (DSRC) link on the 5.9GHz band, and cellular communication (C-V2X). Either of these methods would allow vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication. This technology allows, for instance, a potential reduction in
rear-end collisions by monitoring obstacles in front of or behind the vehicle and automatically applying the brakes when necessary. This technology, however, is limited by the sensing range of vehicle-based radar, particularly in
angled and left-turn collisions, such as a motorist losing control of the vehicle during an impending
head-on collision. The rear-end collisions addressed by current technology are generally less severe than angled, left-turn, or head-on collisions. VII promotes the development of a direct communication link between road vehicles and all other vehicles nearby, allowing for the exchange of information on vehicle speed and orientation or driver awareness and intent. This real-time exchange of information may enable more effective automated emergency maneuvers, such as
steering, decelerating, or
braking. In addition to nearby vehicle awareness, VII promotes a communication link between vehicles and
roadway infrastructure. Such a link may allow for improved real-time
traffic information, better
queue management, and feedback to vehicles. Existing implementations of VII use vehicle-based sensors that can recognize and respond to
roadway markings or
signs, automatically adjusting vehicle parameters to follow the recognized instructions. However, this information may also be acquired via roadside
beacons or stored in a
centralized database accessible to all vehicles.
Efficiency With a VII system in place, vehicles will be linked together. The
headway between vehicles may therefore be reduced so that there is less empty space on the road, increasing the available capacity per lane. More capacity per lane will in turn imply fewer lanes in general, possibly satisfying the community's concerns about the impact of roadway widening. VII will enable precise
traffic-signal coordination by
tracking vehicle
platoons and will benefit from accurate timing by drawing on
real-time traffic data covering volume, density, and turning movements. Real-time traffic data can also be used in the design of new roadways or modification of existing systems as the data could be used to provide accurate origin-destination studies and turning-movement counts for uses in
transportation forecasting and
traffic operations. Such technology would also lead to improvements for
transport engineers to address problems whilst reducing the cost of obtaining and compiling data. Tolling is another prospect for VII technology as it could enable roadways to be automatically tolled. Data could be collectively transmitted to road users for in-vehicle display, outlining the lowest cost, shortest distance, and/or fastest route to a destination on the basis of real-time conditions.
Existing applications To some extent, results along these lines have been achieved in trials performed around the globe, making use of
GPS,
mobile phone signals, and
vehicle registration plates.
GPS is becoming standard in many new high-end vehicles and is an option on most new low- and mid-range vehicles. In addition, many users also have mobile phones that transmit trackable signals (and may also be GPS-enabled). Mobile phones can already be traced for purposes of emergency response.
GPS and
mobile phone tracking, however, do not provide fully reliable data. Furthermore, integrating mobile phones in vehicles may be prohibitively difficult. Data from mobile phones, though useful, might even increase risks to motorists as they tend to look at their phones rather than concentrate on their driving.
Automatic registration plate recognition can provide large quantities of data, but
continuously tracking a vehicle through a corridor is a difficult task with existing technology. Today's equipment is designed for data acquisition and functions such as
enforcement and tolling, not for returning data to vehicles or motorists for response.
GPS will nevertheless be one of the key components in VII systems. ==Limitations==