Real-Time System Management Information Program Data Exchange Format Specification
1. Introduction
1.1 Scope
This document describes the Data Exchange Format Specification (DXFS) for specifying the implementation of a Real-Time System Management Information Program (RTSMIP) at a state or regional level. The RTSMIP provides access to traffic and travel conditions information, prepared by State DOTs and other responsible agencies operating transportation infrastructure, to other public agencies, the traveling public, and entities who may deliver value-added information products.
The DXFS is a detailed specification of the key interfaces defined as part of the RTSMIP. The DXFS is not a new ITS standard; rather it is a specification of existing ITS standards that can address a set of user needs which support a RTSMIP.
1.2 References
The references cited or used in this document are listed below.
- Institute of Electrical and Electronics Engineers (IEEE) Standard 1362-1998 IEEE Guide for Information Technology, System Definition, Concept of Operations (ConOps) Document.
- Cambridge Systematics Inc. Report: Real-Time System Management Information Program (RTSMIP) Data Exchange Format Specification, and Implementation Guidance, User Needs Interview Summary, Technical Memorandum, January 31, 2012.
- Federal Highway Administration 23 CFR Part 511, Real-Time System Management Information Program, November 8, 2010.
- American Association of State Highway and Transportation Officials (AASHTO) and Institute of Transportation Engineers (ITE). Traffic Management Data Dictionary (TMDD) Standard for the Center to Center Communications. Version 3.03a. Volume II, Design Content. August 8, 2013.
- Technical Committee CEN/TC 278 “Road transport and traffic telematics”. Draft European Standard Public transport – Service interface for real-time information relating to public transport operations – Part 1: Context and framework, prEN_15531-1_(E)-SIRIv2.0 Part1-v05.doc STD Version 2.1c, 2012-01.
- Technical Committee CEN/TC 278 “Road transport and traffic telematics”. Draft European Standard Public transport – Service interface for real-time information relating to public transport operations – Part 3: Functional service interfaces, prEN_15531-3_(E)-SIRIv2.0 Part3-v06.doc STD Version 2.1c, 2012-01.
- APTA TCIP-S-001 3.0.6, APTA Draft Standard for Transit Communications Interface Profiles, Version 3.0.6 Volume II TCIP Data and Dialog Definitions.
- OASIS Emergency Management Technical Committee, OASIS Common Alerting Protocol, v. 1.1, October 2005.
- National Weather Service, NWS Watches, Warnings, and Advisories using CAP and ATOM based Formats, Service Description Document.
- NTCIP 2306 version 01 National Transportation Communications for ITS Protocol Application Profile for XML Message Encoding and Transport in ITS Center-to-Center Communications, December 2008.
- SAE-J2266 Location Referencing Message Specification (LRMS), SAE International, October 2004.
1.3 General Statements
Not applicable.
1.4 Terms
For the purposes of this document, the following terms and definitions apply.
Table 1. Terms and Definitions.
| Term |
Description |
| 23 CFR 511 |
FHWA rule defining the Real-Time System Management Information Program. This rule establishes minimum parameters and requirements for States to make available and share traffic and travel conditions information via real-time information programs. |
| Aftermarket Safety Device |
A connected device that may operate while it is mobile, but which is not connected to the data bus of a vehicle. |
| Average Speed |
The summation of the instantaneous or spot-measured speeds at a specific location of vehicles divided by the number of vehicles observed (MUTCD Section 1A.13) |
| Block |
The daily sequence of revenue and non-revenue trips assigned to a transit vehicle in revenue service from pull-out to pull-in. |
| Connected Vehicle RSU |
Any roadside unit device used to transmit to or receive messages from similar devices located on vehicles. |
| Connected Vehicle |
A vehicle containing an on-board unit or aftermarket safety device. |
| Public Safety Center |
Public Safety centers, as discussed in the context of RTSMIP user needs include 911 centers, PSAPs, and other first responder dispatch functions. Under certain conditions the EMC could include Emergency Operations Centers. |
| Environmental Conditions Data |
Current road conditions (e.g., surface temperature, subsurface temperature, moisture, icing, treatment status) and surface weather conditions (e.g., air temperature, humidity, air pressure, wind speed, precipitation, visibility) as measured and reported by fixed and/or mobile environmental sensors and aggregated by the data collector. Attributes relating to the data collection (and aggregation) are also included. |
| Identifier |
A unique number assigned to an item (bus, employee, trip, stop, stop point etc.) to provide a short and uniform way to reference that item, as distinct from all other items of the same type. |
| Intelligent Transportation Systems (ITS) |
Systems that apply modern technology to transportation problems. Another appropriate meaning of the ITS acronym is integrated transportation systems, which stressed that ITS systems will often integrate components and users from many domains, both public and private. |
| Node |
A point within a network. Nodes provide a geographic location that can represent the beginning and end points of a link, location of a device, intersection, or location of an event. |
| On-Board Unit |
A vehicle mounted device used to transmit and receive a variety of message traffic to and from other connected devices (other OBUs and RSUs). Among the message types and applications supported by this device are vehicle safety messages, a primary subject of this standard, used to exchange information on each vehicle’s dynamic movements for coordination and safety. |
| Peer Transportation Agencies |
Since the RTSMIP is meant primarily for state DOTs and transportation agencies in large metropolitan areas, peer transportation agencies would include state DOTs, as well as regional and municipal transportation agencies. |
| Planned Event |
A planned event is a construction event or special event that is projected to occur and may include timeline schedule elements. |
| Roadway Link |
A roadway between two nodes. |
| Service Alert |
Transit service alerts provide updates whenever there is disruption on the network, including route delays or route cancellations. |
1.5 Abbreviations
The abbreviations used in this Document are defined as follows:
Table 2. Abbreviations.
| Abbreviation |
Description |
| AVL |
Automatic Vehicle Location |
| CAP |
Common Alerting Protocol |
| CCTV |
Closed Circuit Television |
| ConOps |
Concept of Operations |
| DMS |
Dynamic Message Sign |
| DXFS |
Data eXchange Format Specification |
| EM |
Emergency Management Subsystem |
| HAR |
Highway Advisory Radio |
| ISPS |
Information Service Provider Subsystem |
| MTA |
Metropolitan Transportation Authority |
| MTC |
Metropolitan Transportation Commission |
| NRTM |
Needs to Requirements Traceability Matrix |
| OBU |
On-board Unit |
| PSAP |
Public Safety Answering Point |
| RDS |
Radio Data System |
| RS |
Roadside Subsystem |
| RSU |
Roadside Unit |
| RTSMIP |
Real-Time System Management Information Program |
| SAFETEA-LU |
Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users |
| SIRI |
Service interface for real-time information relating to public transport operations |
| TCIP |
Transit Communications Interface Profile |
| TMC |
Traffic Management Center |
| TMDD |
Traffic Management Data Dictionary |
| TMS |
Traffic Management Subsystem |
| TPEG |
Transport Protocol Experts Group |
| TRMS |
Transit Management Subsystem |
| VS |
Vehicle Subsystem |
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