Integrating Dynamic Vehicle Probe Data into an Advanced Traffic Management System
Intelligent Vehicle Systems

Connected Vehicle Technology related research is being funded internally by SwRI and conducted with the Connected Vehicle Program and commercial vehicle operations requirements firmly in mind, exploring:

• How vehicles and roadside units will communicate
• What data will be important
• How traffic management centers, automobile manufacturers, and the traveling public will use these data

The SwRI team completed a program to prototype a system that would allow for an investigation into the feasibility of integrating dynamic vehicle data into an advanced traffic management system.

Vehicle Infrastructure Integration Background

From a traffic management perspective, one of the primary advantages to a closed-loop, intelligent highway-intelligent vehicle system is the ability to use individual vehicles as probes to deliver traffic-related data to an Advanced Traffic Management System (ATMS) in near-real time. For example, a vehicle could communicate such things as airbag deployment, braking, vehicle speed, engine RPM, or headlight and windshield wiper usage to help traffic managers. Benefits include:

• Smoothing of traffic conditions
• Development of traffic trends
• Roadway infrastructure analysis
• Emergency responders deployment
• Increase in the flow of traffic through construction zones

Limited research existed assessing the feasibility of integrating the dynamic vehicle probe data directly into an ATMS. SwRI has utilized staff experience and capabilities to make this integration possible through various communication mediums.

The Solution for Integrating with an ATMS

To experiment with how probe data can be integrated with an ATMS, the team selected a 2006 sport-utility vehicle, equipped with ISO-certified communications for its on-board system diagnostics, as a test vehicle. Engineers added a single-board computer and GPS system and developed a software algorithm to assess pertinent vehicle data over the vehicle's CANbus. Investigators compiled a cross-section of the available vehicle data set and converted it into an Extensible Markup Language (XML) message—the standard format for ATMSs. The onboard wireless equipment uploads XML messages via roadside equipment to a modified ATMS.

The vehicle is equipped with a GPS receiver connected to the on-board computer to provide location and heading information. To extract and transmit the data from the vehicle to the roadside infrastructure, SwRI engineers had to overcome idiosyncrasies that were limiting the operating system's interactions with the vehicle CANbus as well as other problems integrating GPS and CAN data. The team developed processes that poll the vehicle CANbus for the desired dataset to provide a "snapshot" of data that could then be packaged into an XML message for transmission to the infrastructure. When disconnected from the infrastructure, the vehicle's system stores the snapshots, eventually replacing the oldest with the most current dataset available.

Prototype System for Integrating Dynamic Vehicle Data

SwRI engineers developed three software applications for the prototype system:

• Connection manager—provides infrastructure logic necessary to manage connections with the roadside components and monitors access point and subscriber unit connectivity
• VII manager subsystem
• Map interface plugin—simulates a traffic management system interface. The map interface application is an ATMS map application developed for Texas Department of Transportation Intelligent Transportation System (TxDOT ITS).

The application follows the following protocol:

1. The application broadcasts a user datagram protocol beacon message that contains TCP/IP connection information.
2. Devices anonymously connect to the infrastructure and a connection is established.
3. The vehicle components start sending data snapshots bundled in a probe message format.
4. These messages are forwarded to a subcomponent of the VII Manager application, known as the driver.
5. The driver translates the raw CANbus data into decipherable formats.
6. The translated data are then transferred to the core VII manager subsystem, which stores the data for use by a consuming application, such as mapping or data warehousing.

In the SwRI implementation, a mapping application provides a graphical representation of the data on a map generated by Microsoft® MapPoint®. SwRI engineers added dialog boxes to the mapping application to view the zone configuration information, snapshot-specific data, and transportation data across the zone such as speed, volume, and occupancy. The mapping application provides a near-real time data snapshot of the information available to a Traffic Management Center (TMC) operator.

A prototype roadside system was installed along the SwRI test track to establish three connectivity scenarios that mimic the anticipated hotspot coverage of Dedicated Short-Range Communications (DSRC) environments. The team optimized radio placement and power settings to more realistically evaluate the system if implemented as a series of hot spots. Hot spot coverage can be likened to geographically spotty coverage. The connectivity scenarios include:

• Covering the entire test track to simulate constant transmission coverage within a zone
• A single zone over a partial section of the track to simulate a vehicle entering and exiting a single zone
• Two separate zones to simulate a vehicle moving through multiple zones

This testing was critical to understanding how the probe data system would handle limited hot spot-like coverage if deployed along a roadway infrastructure.

Future of Advanced Traffic Management Systems

By successfully integrating dynamic vehicle probe data into an ATMS, SwRI has taken the first step in implementing a probe solution along the nation's highways. Fusing the probe data with existing transportation data will yield enhanced, super data, such as:

• Transportation speed sensors
• Incident management
• Weather collection

These super data will accomplish:

• More precise transportation management
• Data collection and reporting
• Emergency response
• Information management
• Transportation modeling

This, in turn, will improve the safety and mobility of the macro transportation system. This vehicle-to-roadway data exchange is the first of many applications that SwRI will develop to close the loop on the coordinated intelligent highway-intelligent vehicle system of the future.

Related Terminology

intelligent transportation systems  •  ITS  •  automation and data systems  •  advanced traffic management system  •   ATMS  •  vehicle infrastructure integration