National VII Architecture – Data Perspective

Michael Schagrin
ITS Joint Program Office
Research and Innovative Technology Administration
TRB 2008 Annual Meeting Session 415
January 16, 2008

Powerpoint Version


National Architecture Overview

  • Data Within VII Infrastructure
  • Applications Enabling Services
  • Proof of Concept Applications
  • Issues Relevant to Use of VII Data

VII Vision

  • Linking vehicles and the transportation infrastructure into an integrated, nationwide system has been a vision of the U.S. Department of Transportation (USDOT) for almost two decades.
  • VII technologies, network and services are designed to support applications facilitating three major goals: Safety,Mobility and E-Commerce

VII National Architecture Framework

  • Wireless communications uniquely tailored for vehicular environment
  • Secure communications between service providers and vehicles
  • Architecture designed around DSRC, however extendable to other wireless communications technologies
  • Data collection / message distribution functions common to many applications are provided as core services… enabling rapid applications development

VII Enables Collection, Distribution and Exchange of Data

Vehicle to Infrastructure

  • Probe Data
  • Trip Path Data (opt-in)
  • Transaction Data (e.g., E-Payment)

Infrastructure to Vehicle

  • Advisory Message Data
  • Localized Map Data (safety)
  • Signal Phase & Timing Data
  • Position Corrections
  • Transaction Data (e.g., E-Payment)

Vehicle to Vehicle

  • Heartbeat Data

VII Enabling Services − Probe Data Distribution

  • This service collects probe data from vehicles and distributes to interested users (e.g., Traffic Management Centers, Information Service Providers)
  • Provides real time data to enable determination of roadway conditions
  • Probe Data includes vehicle position, speed, direction of travel and vehicle kinematics data, etc. (SAE J2735)
  • Applications that utilize Probe Data include Traveler Information, Signal Timing Optimization, Winter Maintenance, and Road Weather Prediction
  • User applications “subscribe” to receive specific types of probe data from specific locations
  • Vehicles generate probe data periodically and in response to significant events, “publishing” this data when in range of an RSE
  • Probe data is delivered to applications with matching subscription criteria
  • VII does not provide a data repository for probe data, it merely transports the data
  • Could provide for integrated delivery from other probe data sources

VII Enabling Services − Advisory Message Delivery

  • This service distributes localized advisory messages such as travel times, incident information, local signage
  • Helps drivers make safety and travel decisions based on localized advisories
  • Data types include Signal Phase & Timing (SPAT), Local Signage, Local and Regional Weather Alerts
  • Applications that utilize advisory messages include Intersection Collision Avoidance, Traveler Information, In-Vehicle Signage
  • Provider specifies broadcast locations & delivery schedule
  • Safety messages receive broadcast priority

VII Enabling Services − Map Element Distribution

  • This service provides roadway micro-maps to vehicles
  • Micro-maps are used to support safety applications such as intersection collision avoidance and curve overspeed warning
  • Data includes detailed roadway geometry for signalized intersections, non-signalized intersections, road curve segments
  • System utilizes anonymous probe data to verify map accuracy and to detect potential events

VII Enabling Services − Heartbeat

  • This service is frequent transmission of vehicle speed and location to other vehicles
  • It enables situational awareness for vehicles
  • Data contains vehicle’s position, speed, direction of travel, and size
  • Supports safety applications such as lane changes, forward collision warning, emergency electronic braking

VII Enabling Service − Data Exchange Transport

  • This service supports exchange of opt-in bi-directional transactions between vehicles and service providers
  • It enables an endless variety of public and private applications, where direct communications between service providers and vehicles is needed
  • Data could include vehicle diagnostics information, emissions inspection data, and e-payment transactions
  • Applications could include concierge services, vehicle maintenance, and tolling
  • Vehicle is always the initiator of any transaction, Service Provider and vehicle can then exchange data

Summary of Proof-of-Concept Applications


  • Traveler Information
  • Signal Timing Optimization
  • Ramp Metering
  • Weather Information
  • Corridor Management: Planning Assistance
  • Corridor Management: Load Balancing


  • In-Vehicle Signage
  • Off-Board Navigation
  • Parking Payment
  • Toll Payment


  • Vehicle-to-Vehicle
  • Intersection Violation Warning

Issues Relevant to Use of VII Data

Absolute and Relative Positioning

  • Applications such as intersection collision avoidance and HOT lane tolling require highly accurate (lane-level) vehicle positioning and availability of detailed roadway geometric maps

Data Ownership and Liability

  • Lingering questions of data ownership and rights have the potential to limit the usability of the data
  • Liability associated with VII data ownership must be defined for every entity involved in the system
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