Printable Version

Closing the Safety Loop:

Linking Smart Vehicles with Intelligent Highways

By Ryan D. Lamm and Steven J. Sprouffske

Ryan D. Lamm, left, manages intelligent vehicle systems and networks programs in SwRI’s Automation and Data Systems Division. His expertise is in intelligent vehicle systems, communication system design and network engineering. Steven J. Sprouffske is a research analyst with experience in cooperative vehicle and traffic management systems. He is involved with standards development for the Vehicle Infrastructure Integration initiative and cooperative vehicle systems.

Each year, one million people die in car accidents worldwide, including 40,000 in the U.S. Meanwhile, traffic congestion tends to increase proportionally with population and prosperity. In the United States, new highway capacity has not kept pace with population growth. Between 1980 and 1999, total highway miles grew by only 1.5 percent while total vehicle travel mileage increased 76 percent.

For many years, the automotive industry and federal and state departments of transportation have been developing systems to tackle safety and mobility problems in their respective domains. Many new automobiles have advanced vehicle safety systems that enhance driver perception and aid, to some degree, in driver response. In the public sector, meanwhile, complex Intelligent Transportation Systems (ITS), also known as intelligent highways, enhance traffic flow. While these systems have each made positive steps toward reducing fatalities and congestion, many within the ITS community believe the greatest benefit could be realized through coordination between vehicles and highway systems and among vehicles themselves.

The Federal Highway Administration (FHWA) recently established the Vehicle Infrastructure Integration (VII) initiative to improve safety and mobility on the nation’s roadways by supporting efforts to integrate standardized traffic management communication infrastructure with vehicle systems. The FHWA and major participating auto manufacturers are working with other private industry groups to develop vehicle-to-vehicle and vehicle-to-infrastructure communications capable of exchanging critical information. The marriage of the intelligent vehicle and the intelligent highway is expected to enhance public safety and improve the mobility of the overall transportation system.

Southwest Research Institute (SwRI), a pioneer in ITS technology with extensive experience in communications technologies and software development, is participating in a number of industry and standards activities to help bring the VII vision to reality. Over the past decade, SwRI has developed and integrated San Antonio’s TransGuide™ and Florida’s SunGuideSM systems, gaining extensive expertise in creating and integrating advanced traffic management systems (ATMS) and technologies. The Institute also serves as the statewide ITS integrator for Texas.

SwRI is developing applications that will allow vehicles to alert approaching vehicles of traffic situations, such as in an emergency braking scenario, to help prevent secondary incidents that often occur.

Vehicle Infrastructure Integration (VII)

In 2003, the Federal Communications Commission (FCC) allocated spectrum for Dedicated Short Range Communications (DSRC) in the ITS Radio Service 5.9 GHz band. The 5.9 GHz DSRC radio system features a range of between 300 and 1,000 meters, low-latency transmission, fast network acquisition, high link reliability and the ability to prioritize the transmission of specific, safety-related data. Since the spectrum was established, ITS organizations including SwRI have been developing standards, prototype devices, applications, and networks to demonstrate how DSRC would operate in typical vehicular environments.

The VII system will include components inside vehicles and along the roadways, plus a nationwide, Internet Protocol version 6 (IPv6)-based network to collect and distribute data. Equipment in vehicles would include a DSRC radio, a Global Positioning System (GPS) receiver, and interfaces for both the driver and vehicle systems. Meanwhile, the roadside equipment will include a DSRC radio and GPS receiver, plus a network interface for transmitting the VII data. Multiple, well-defined network interfaces are under development to allow approved entities to gain access to the VII system to extract or provide relevant information.

More than 100 potential applications of this technology have been envisioned, such as advanced vehicle-to-vehicle emergency braking notification, signal violation warnings, roadway condition reporting, vehicle probe data, electronic payment for open-road tolling, emergency vehicle alerts and support for in-vehicle signage.

Full realization of VII on a nationwide scale ultimately depends on the USDOT deploying and maintaining between 100,000 and 400,000 roadside devices, and on the automotive industry’s installing compatible on-board systems in their production vehicles. A public-private sector agreement is anticipated by late 2008, and a projected 27 percent of the passenger car fleet could be equipped with VII technology by 2015. Until then, various test beds are evaluating and proving the effectiveness of various VII technologies.

The communications devices are critical to VII success, and SwRI was selected by the OmniAir Consortium Inc., to develop the 5.9-GHz DSRC standards conformance test methods for the OmniAir DSRC certification program. OmniAir, a nonprofit public-private consortium, is under a five-year contract to the Federal Highway Administration to develop a certification program deemed essential to the forward progress of the VII initiative. The SwRI team is developing the standards conformance test methods focused on Institute of Electrical and Electronics Engineers (IEEE) P1609.2-4 DSRC standards.

The Institute also is internally funding VII research, exploring how vehicles and roadside units will communicate, what data will be important and how traffic management centers will use these data. The SwRI team also is investigating the feasibility of integrating dynamic vehicle data into advanced traffic management systems.

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 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 smooth traffic conditions and to develop traffic trends, analyze roadway infrastructure, deploy emergency responders and increase the flow of traffic through construction zones.

SwRI engineers are in the final stages of an internally funded project addressing the challenges and demonstrating the practicality of collecting and integrating vehicle data into an ATMS.

Emergency response vehicles with right-of-way, such as ambulances or fire trucks, could alert vehicles nearing an intersection that they were approaching, to more safely and efficiently pass through traffic.

Prototype VII system

Using a one-mile vehicle test track that SwRI previously has used to evaluate various ITS wireless communication infrastructures, SwRI engineers evaluated the feasibility of integrating dynamic probe data into a modified ATMS by prototyping a simplified VII system with vehicle, roadside and Traffic Manager Center (TMC) components.

The team selected a 2006 sport-utility vehicle, equipped with ISO-certified communications for its on-board system diagnostics, as a test vehicle. They added a single-board computer and GPS system and developed a software algorithm to access pertinent vehicle data via 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 data format for ATMS. The onboard equipment wirelessly uploads XML messages via roadside equipment to a modified ATMS.

On-board vehicle components

The vehicle had a GPS receiver connected to the on-board computer to provide location and heading information. To extract data from the vehicle and transmit it 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 on-board equipment included a single-board computer and a GPS system. Using a software algorithm to access vehicle data and convert it to an ATMS standard data format, the system wirelessly transmitted data to roadside equipment.

Roadside communications devices

Because DSRC-capable devices were not yet available, the SwRI team used IEEE 802.11a radios and cellular modems to serve as the system’s communications channel. A prototype roadside system was installed along the SwRI test track to establish three connectivity scenarios that mimic the anticipated hotspot coverage of 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, and 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.

Traffic management system components

To simulate a traffic management environment, SwRI engineers developed three software applications for the prototype system: a connection manager, a VII manager sub-system and a map interface plug-in. The connection manager provides the infrastructure logic necessary to manage connections with the roadside components, and it also monitors access point and subscriber unit connectivity. The application broadcasts a user datagram protocol beacon message that contains TCP/IP connection information. This setup allows devices to anonymously connect to the infrastructure. Once a TCP/IP connection is established, the vehicle components start sending data snapshots bundled in a probe message format.

These messages are then forwarded to a sub-component of the VII manager application, known as the driver. The driver translates the raw CANbus data into decipherable formats. The translated data is then transferred to the core VII manager sub-system, which stores it 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 Map Point. The map interface is an ATMS map application developed for TxDOT ITS. SwRI engineers added dialogs to the mapping application to view the zone configuration information, snapshot-specific data and transportation data across the zone, including speed, volume and occupancy. The mapping application provides a near-real time data snapshot of the information available.

After development and testing in the lab, the team deployed the prototype system at the SwRI test track to evaluate system performance over the three connectivity scenarios. Implementations proved the feasibility of integrating VII data into existing ATMS and yielded valuable insight into how a similar system would function when deployed along a highway. Visually representing the probe data in an ATMS provided a very dynamic feel that enhances the current transportation management implementations.

Implications for future VII technology

By successfully integrating dynamic vehicle probe data into 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, such as transportation speed sensors, incident management, and weather collection, will yield enhanced, super data for more precise transportation management, data collection and reporting, emergency response, information management and 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 cooperative intelligent-highway, intelligent-vehicle systems of the future.

While still years from the science-fiction scenarios of futuristic vehicles that drive themselves, the VII technologies that SwRI is developing are paving the way for a host of new technologies to make highway travel safer and more efficient.

Intelligent Transportation Systems

Southwest Research Institute has pioneered the evaluation, development, deployment, and verification of ITS software and hardware since 1992. Its engineers apply communications and software engineering skills to the specification, design, and development of integrated, interconnected “smart” transportation systems. SwRI’s ITS systems combine information processing, communications, control, and electronics and SwRI engineers have experience in the four major subsystems identified in the national ITS architecture: traveler, centers, vehicles and roadside.

SwRI staff members have instrumental roles in developing national ITS standards and extensive experience with traffic management systems deployed around the country, including implementing extensive ITS programs for Florida and Texas.

SwRI has pioneered the development, deployment, evaluation and verification of ITS software and hardware since 1992. The Institute served as system integrator for the TransGuide ITS system in San Antonio and is the statewide ITS integrator for Texas. San Antonio’s TransGuide control center is pictured above.

Comments about this article? Contact Lamm at (210) 522-5350 or

Published in the Spring 2007 issue of Technology Today®, published by Southwest Research Institute. For more information, contact Joe Fohn.

Spring 2007 Technology Today
SwRI Publications SwRI Home