Transit Vehicle (Subsystem*)

The Transit Vehicle Subsystem (TRVS) resides in a transit vehicle and provides the sensory, processing, storage, and communications functions necessary to support safe and efficient movement of passengers. The types of transit vehicles containing this subsystem include buses, paratransit vehicles, light rail vehicles, other vehicles designed to carry passengers, and supervisory vehicles. The subsystem collects accurate ridership levels and supports electronic fare collection. The subsystem supports a traffic signal prioritization function that communicates with the roadside subsystem to improve on-schedule performance. Automated vehicle location functions enhance the information available to the Transit Management Subsystem enabling more efficient operations. On-board sensors support transit vehicle maintenance. The subsystem supports on-board security and safety monitoring. This monitoring includes transit user or vehicle operator activated alarms (silent or audible), as well as surveillance and sensor equipment. The surveillance equipment includes video (e.g. CCTV cameras), audio systems and/or event recorder systems. The sensor equipment includes threat sensors (e.g. chemical agent, toxic industrial chemical, biological, explosives, and radiological sensors) and object detection sensors (e.g. metal detectors). In addition, the subsystem supports vehicle operator authentication prior to operation of the vehicle and remote vehicle disabling. The subsystem also furnishes travelers with real-time travel information, continuously updated schedules, transfer options, routes, and fares.

Subsystem Interfaces Diagram

This is a context diagram for the entity Transit Vehicle Subsystem that shows the interfaces to subsystems and every architecture flow that this entity sends or receives, as defined in the National ITS Architecture. A complete list of all architecture flows shown on this diagram, is available under the Inputs/Outputs section on this page.
Transit VehicleTransit ManagementEmergency ManagementVehicleRoadwayalarm notificationdemand response passenger and use datatransit traveler requesttransit vehicle location datatransit vehicle operator authentication informationtransit vehicle schedule performancealarm acknowledgefare management informationremote vehicle disabletransit schedule informationtransit traveler informationtransit vehicle operator authentication updatetransit vehicle operator informationalarm notificationsecure area sensor datasecure area surveillance datatransit vehicle location dataalarm acknowledgesecure area sensor controlsecure area surveillance controlvehicle signage datalocal signal priority request
Get the Source Graphic, a Enhanced Windows Metafile (EMF), in ZIP format.

Terminator Interfaces Diagram

This is a context diagram for the entity Transit Vehicle Subsystem that shows the interfaces to subsystems and every architecture flow that this entity sends or receives, as defined in the National ITS Architecture. A complete list of all architecture flows shown on this diagram, is available under the Inputs/Outputs section on this page.
Transit VehicleTravelerTraveler CardTransit Vehicle OperatorBasic Transit VehicleSecure Area EnvironmentLocation Data Sourcetraveler interface updatesboarding and alightingtraveler inputsrequest for paymentpaymenttransit vehicle operator displaytransit vehicle operator inputsbasic transit vehicle controlstransit vehicle measuressecure area characteristicsposition fix
Get the Source Graphic, a Windows Metafile (WMF), in ZIP format.

Security Considerations:

The Transit Vehicle Subsystem (TRVS) is the communications path that connects transit personnel in the field with central dispatch at the transit management center. This subsystem provides the functions necessary to support the safe and efficient movement of passengers. Most of the information that is handled by the TRVS is not particularly sensitive except for financial transactions associated with electronic payment media, and the information flows used for operator authentication on the vehicle or remote vehicle disabling. Operator authentication is used to prevent unauthorized vehicle operation, and remote disabling is provided as one aspect of response to on-board threats. The security considerations for the Transit Vehicle Subsystem relate to physical security of the vehicle, transit vehicle operators, and travelers using the vehicle. The TRVS is exposed to certain threats including unauthorized access or control (hijacking) and disruption of services. Other security objectives for TRVS are availability and integrity – the services and information provided by the TRVS must be available and accurate so that transit operations are not degraded. The basic transit vehicle operator communications, tracking, and routing functions provided by the TRVS are not particularly sensitive from a security standpoint. They do not directly affect public safety – disruption of service would be mainly an inconvenience. The TRVS represents a wide range of vehicles including articulated and double-decked buses, paratransit vehicles, ferryboats, light and commuter rail, monorail vehicles, school buses, trolley buses, vans, tow trucks, shelter service trucks. This collection of vehicles may have different security requirements, depending on the functions supported, the data that is stored, and the services provided. Passenger carrying transit vehicles have additional security concerns beyond those vehicles that do not carry passengers, namely the physical security of the passengers, and the protection of financial or personal information relating to electronic fare payment systems. For example, threat sensors, surveillance, and alarms are used to identify threats on-board a vehicle, and there are confidentiality issues associated with all financial transactions. The primary security consideration for supervisory or support vehicles is the physical security of the vehicle and the vehicle operator. There are also other variables that impact security that are independent of vehicle type. For example, as new systems are deployed on a bus, the transit vehicle operator must become familiar and comfortable with their usage. Until the operator is familiar with these systems, they may be vulnerable to attack (or the information that is stored and sent to the TRMS may be vulnerable) and security may be an issue. The specific analysis of the security objectives, threats, vulnerabilities to those threats, and appropriate security services to address the vulnerabilities should be undertaken for systems associated with the TRVS.

Functionality: Equipment Packages* and PSpecs*

Inputs/Outputs: Architecture Flows* and Data Flows*

Basic Transit Vehicle flows into Transit Vehicle

Emergency Management flows into Transit Vehicle

Location Data Source flows into Transit Vehicle

Secure Area Environment flows into Transit Vehicle

Transit Management flows into Transit Vehicle

Transit Vehicle flows into Basic Transit Vehicle

Transit Vehicle flows into Emergency Management

Transit Vehicle flows into Roadway

Transit Vehicle flows into Transit Management

Transit Vehicle flows into Transit Vehicle Operator

Transit Vehicle flows into Traveler

Transit Vehicle flows into Traveler Card

Transit Vehicle flows into Vehicle

  • vehicle signage data (Architecture Flow*) - In-vehicle signing data that augments regulatory, warning, and informational road signs and signals. The information provided would include static sign information (e.g., stop, curve warning, guide signs, service signs, and directional signs) and dynamic information (e.g., current signal states, grade crossing information, local traffic and road conditions, advisories, and detours).
    Data Flows*:

Transit Vehicle Operator flows into Transit Vehicle

Traveler flows into Transit Vehicle

Traveler Card flows into Transit Vehicle