Section 2 - Requirements Overview
This section provides an overview of the technical requirements identified for the CHART communications network: the field transportation management devices to be connected to the CHART network, CHART information user sites, CHART information distribution, and network availability. Sections 2.1 - 2.6 present background and supporting material for the actual statement of requirements in Section 2.7. During the course of study, some requirements may have changed. Existing SHA communications capacity available to support CHARTas well as various constraints on communications are also discussed.
The CHART program has four general ITS goals:
Traffic and Roadway Monitoring - around-the-clock monitoring of traffic conditions in real-time in order to reduce the time required to respond to traffic incidents as they happen. This includes requirements to monitor and detect vehicle speed, volume, density, travel time, queue length, identification and position; weather/pavement conditions; and monitor video or photographic images of events on the roadways.
Incident Management - reaching and removing roadway blockages with the goal of returning to normal flow of traffic in the safest way and in the shortest time. Incidents that require response include accidents, disabled vehicles, spilled loads, bad weather, special sporting or other public events, construction, roadway maintenance, and evacuations. Significant study efforts have shown that detection and verification or validation of incidents within 5 to 10 minutes and initiation of response to validated incidents within 10 to 20 minutes is a valid target. This 5 to 10 minute validation window is one of the essential business cases for CHART systems and underlying telecommunications networks and should be used as a yardstick to measure the validity of all other derived or secondary requirements.
Traveler Information - disseminating pre-trip and en-route information to travelers directly and/or through the media so that optimal decisions can be made with respect to timing of the trip, available modes of transportation, route selection, and necessity of traveling at all.
Traffic Management - coordinating all of the above with other traffic-related systems to perform comprehensive management of traffic operations. Requirements for integration include traffic and other surface signal control systems, ramp metering, electronic toll collection, and commercial vehicle operation.