The source graphic, a Windows Metafile (WMF), for the TSDs can be downloaded here:
TSD Part 1,
TSD Part 2,
TSD Part 3,
The following discusses how the National ITS Architecture provides the transportation service described by this service package. Each numbered item describes the operation of that portion of the service package identified with the corresponding number on the transaction set diagram.
The entire process is under the asynchronous monitoring (ISP operations information presentation) and control (ISP operator inputs) by the ISP Operator.
As part of the normal operation, ISPs may exchange information (incident information, multimodal information, parking information, road network conditions, traffic images, and transit service information) for a variety of reasons: contractual information access restrictions, proprietary data sources, economy of scale, cooperative agreements, etc. This ISP coordination is often in the form of a bulk data exchange. While necessary for route guidance, the information is not usually sent piecemeal for a specific route.
Periodically, possibly by subscription or by regularly scheduled requests, the Vehicle Subsystem and the Personal Information Access Subsystem (e.g. personal computing devices) may request (map update request) and download map updates from a Map Update Provider.
Schedule information for alternate mode transportation providers such as train, ferry, and air (multimodal information) are received by Information Service Providers as either direct response to their requests or as subscription transactions. The schedules might also be pushed solely by the Multimodal Transportation Service Provider according to a pre-arranged agreement (multimodal information request).
All (or selected) collected road network conditions, traffic images and incident information are provided by the Traffic Management Subsystem to Information Service Providers as either a direct response to requests or as subscription transactions. The information might also be pushed solely by the Traffic Management Subsystem according to a pre-arranged agreement.
All (or selected) transit and fare schedules and transit schedule adherence information are received from the Transit Management Subsystem by Information Service Providers as either direct response to their requests or as subscription transactions. Specific transit route recommendations and advanced fare payments may also be supported when explicitly requested by the Information Service Provider (transit information request). These requests for transit information or services are confirmed by the Transit Management Subsystem (transit request confirmation).
The Maintenance and Construction Management Subsystem provides current asset restrictions for the road network (e.g. height, weight, or width restrictions).
Prior to beginning the route request process, the traveler, using a PIAS, may submit a traveler profile, which will identify recurring trip characteristics, personal preferences, or equipment capabilities. To begin the route selection process a traveler may, asynchronously, and as often as desired, request (traveler inputs) a route through the Personal Information Access Subsystem, PIAS (e.g. a personal computing device such as a PDA, cell phone, PC, or other mobile device) or via the Remote Traveler Support Subsystem, RTS (e.g., a kiosk).
Once a route is requested by the traveler, a continuous cycle occurs, consisting of these steps:
Once the Traveler has accepted a route, a trip confirmation that the trip has been accepted is sent back to the ISP.
The updated position of the traveler (position fix) may be obtained for the case of a mobile user making the route request via the PIAS.
The travelerís trip request is sent from the PIAS or RTS.
The Information Service Provider sends suggested route information (trip plan).
The PIAS or RTS presents the route/trip to the Traveler (traveler interface updates), and then the traveler either accepts the route (and the cycle stops) or asks for another route (and the cycle repeats).
A similar set of flows can be used by a Driver to obtain route information. The driver may submit (through the Vehicle Subsystem) a traveler profile, which will identify recurring trip characteristics, personal preferences, or equipment capabilities. Then, asynchronously, and as often as desired, a driver may make a route request (driver inputs) to the Vehicle Subsystem.
Once a route is requested by the Driver (driver inputs), a continuous cycle occurs, consisting of these steps:
Once the Driver has accepted a route, a trip confirmation that the trip has been accepted is sent back to the ISP.
The updated position of the driver (position fix) is obtained.
The driverís trip request is sent from the Vehicle Subsystem to the ISP.
The ISP sends suggested route information (trip plan).
The Vehicle Subsystem presents the route/trip to the Driver (driver updates), and then the driver either accepts the route (and the cycle stops) or asks for another route (and the cycle repeats).
The ISP may provide specialized routing services for other types of clients. For example the Fleet and Freight Management Subsystem may request a route (route request) from the ISP. The computed route is returned by the ISP (route plan). Prior to calculating routes, the ISP periodically and asynchronously receives route restrictions from the Commercial Vehicle Administration Subsystem. These could include hazmat route restrictions or other vehicle size and weight limitations.
The ISP may arrange for parking lot reservations by making a parking reservations request to the Parking Management Subsystem, which can respond with a parking lot reservation confirmation, confirming that the reservation has been made.
The Traffic Management Subsystem can be notified by the ISP of routes to be taken by guided vehicles (logged vehicle routes) that can be factored into adaptive traffic control strategies.
Additionally, the Transit Management Subsystem can be notified by the ISP of routes to be taken by guided vehicles for use in support of paratransit operations (selected routes).