Link Type: Position Location Interface

Location and Time Data Source --> Transit Vehicle OBE:
location and time

Definitions

location and time (Information Flow): The current geographic location in three dimensions (latitude, longitude, elevation) and the current time.

Location and Time Data Source (Source Physical Object): The 'Location and Time Data Source' provides accurate position information. While a Global Positioning System (GPS) Receiver is the most common implementation, this physical object represents any technology that provides a position fix in three dimensions and time with sufficient accuracy.

Transit Vehicle OBE (Destination Physical Object): The Transit Vehicle On-Board equipment (OBE) 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 physical object include buses, paratransit vehicles, light rail vehicles, other vehicles designed to carry passengers, and supervisory vehicles. It collects ridership levels and supports electronic fare collection. It supports a traffic signal prioritization function that communicates with the roadside physical object to improve on-schedule performance. Automated vehicle location enhances the information available to the transit operator enabling more efficient operations. On-board sensors support transit vehicle maintenance. The physical object 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. It also furnishes travelers with real-time travel information, continuously updated schedules, transfer options, routes, and fares. A separate 'Vehicle OBE' physical object supports the general vehicle safety and driver information capabilities that apply to all vehicles, including transit vehicles. The Transit Vehicle OBE supplements these general capabilities with capabilities that are specific to transit vehicles.

Included In

This Triple is in the following Service Packages:

This Triple is in the following Functional Objects:

This Triple is described by the following Functional View Data Flows:

This Triple has the following triple relationships:

Communication Solutions

  • GNSS Data - GNSS serial interface (6)
Solutions are sorted in ascending Gap Severity order. The Gap Severity is the parenthetical number at the end of the solution.

Selected Solution

GNSS Data - GNSS serial interface

Solution Description

This solution is used within Australia, the E.U. and the U.S.. It combines standards associated with GNSS Data with those for GNSS serial interface. The GNSS Data standards include upper-layer standards required to obtain location and time information from a satellite-positioning-system-based geolocation receiver. The GNSS serial interface standards include lower-layer standards that support communications between connected ITS equipment and geolocation equipment such as a GPS receiver.

ITS Application Entity

NMEA 0183
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Mgmt

No Standard Needed
Facilities

No Standard Needed
Security
Mind the gap

No Standard Needed
TransNet

NMEA 0183
Access
Mind the gap

NMEA 0183
TransNet TransNet

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Facility Facility

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Security Security

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Note that some layers might have alternatives, in which case all of the gap icons associated with every alternative may be shown on the diagram, but the solution severity calculations (and resulting ordering of solutions) includes only the issues associated with the default (i.e., best, least severe) alternative.

Characteristics

Characteristic Value
Time Context Now
Spatial Context Adjacent
Acknowledgement False
Cardinality Broadcast
Initiator Source
Authenticable True
Encrypt True


Interoperability Description
Local In cases where an interface is normally encapsulated by a single stakeholder, interoperability is still desirable, but the motive is vendor independence and the efficiencies and choices that an open standards-based interface provides.

Security

Information Flow Security
  Confidentiality Integrity Availability
Rating Moderate High High
Basis While time reference should be universally available, time reference coupled with vehicle location is tracking data. This flow is internal to a vehicle, but should probably be encrypted to discourage hacking and snooping on the vehicle bus. Thus MODERATE. Location and time data is the basis for crash imminent safety and a host of other applications. Corruption of this flow could lead directly to a vehicle accident. If this information is not available, crash imminent safety applications depending on this information will not function properly.


Security Characteristics Value
Authenticable True
Encrypt True