Exploratory Advanced Research . . . Next Generation Transportation Solutions

Increasing Highway Throughput 

Communications and Control Technologies to Improve Traffic Flow

•	 Achieving closer coordination, shorter vehicle separation gaps, and higher effective

lane capacities through vehicle–vehicle 

communication, vehicle–infrastructure communication (VIC), and cooperative adaptive

cruise control (CACC).

•	 Improving heavy-truck fuel consumption

and doubling the capacity of truck-only

lanes by forming and maneuvering automated three-truck platoons.

Managing Traffic Flow and Density 

The new communication capabilities of VIC can

be used to feed speed advisories directly to

individual drivers. To generate speed guidance,

systems will process highly accurate and complete real-time traffic data collected by instrumented vehicles—data probes that can gather 

information from a longer swath of the traffic

stream than is possible with fixed sensors alone.

The project is developing modeling capabilities 

and design tools for generating these speed

advisories. In addition, to help determine systems feasibility, the researchers are examining

how targeted drivers respond to the guidance 

and how nearby vehicles react when a targeted

vehicle changes speed.

Taking Control for Greater Efficiency

The processing of real-time data from downstream traffic and adjacent lanes, provided by

the moving probe vehicles, will enable CACC to

function in synch with real-time traffic conditions as they evolve, responding to speed and

following-distance commands for optimal flow

moment by moment. With CACC designs that

allow highly accurate and fast responses, shorter time gaps between vehicles can be set and 

the roadway surface area can be used at its

maximum efficiency. The technical feasibility of

this approach will be investigated, and user

acceptance will be assessed.

The Exploratory Advanced Research Program Fact Sheet

Using the Potential of Intelligent 

Infrastructure Effectively

The ability to modulate the speed and spacing of

individual vehicles in relation to unseen events 

further downstream has tremendous potential to

keep traffic flowing smoothly, safely, and at its

optimum density. With the dedicated short-range

communication system being developed under

IntelliDrive (previously the Vehicle–Infrastructure

Integration or VII initiative), such long-range traffic management opportunities are now conceivable. This EAR project is modeling, testing, and

demonstrating prototype systems in three areas:

•	 Improving traffic flow by calculating and communicating speed guidance directly to individual drivers.

How can the new capabilities of

intelligent vehicles and highway

infrastructure be used to reduce congestion and effectively increase highway

capacity? This question is the focus of

“Development and Evaluation of Selected Mobility Applications for VII,” an

Exploratory Advanced Research (EAR)

Program project launched by the Federal Highway Administration (FHWA) in

2007. Researchers at the Partners for

Advanced Transit and Highways (PATH)

program of the University of California,

Berkeley, are conducting the 3-year

project in cooperation with Caltrans.
Maneuvering Three-Truck Platoons 

The tight vehicle-to-vehicle coordination necessary for close-formation platoon driving of

heavy trucks is a major focus of the project.

Building on previous research that successfully

demonstrated two-truck formations driving as

closely as 3 m apart at highway speeds, this

project will advance to three-truck platoons and

will tackle the technical challenges of automating lane changing, merging, and joining and

leaving the platoon. Automated truck speed and

spacing can as much as double lane throughput 

capacity. Close-formation platoons also reduce

aerodynamic drag, with fuel consumption savings—and carbon emissions reductions—in the 

range of 10 to 15 percent. Ultimately, successful

platoon maneuvering on dedicated truck-ways

may accommodate the heavy volumes anticipated in high-density corridors.

Future Efforts

The research underway will discover whether

these next-generation solutions are feasible and,

if so, what further work will be needed to move

them toward deployment as VIC is more fully

implemented. “This project offers highly advanced

strategies to reduce bottlenecks, minimize congestion, and maximize throughput,” says Bob

Ferlis of FHWA’s Office of Operations Research

and Development. “If successful, they have the

potential to increase the effective capacity of

our infrastructure investment.”

In addition to reports describing the results 

of the experiments, the project will produce

software tools used for macroscopic traffic simulation, microscopic simulation of CACC performance, and truck platoon dynamics design and

evaluation. The research will quantify the impact

that the applications are likely to have on highway congestion, throughput, and energy consumption.

What Is the Exploratory 

Advanced Research Program?

FHWA’s Exploratory Advanced Research

(EAR) Program focuses on long-term,

high-risk research with a high payoff

potential. The program addresses underlying gaps faced by applied highway

research programs, anticipates emerging issues with national implications, and

reflects broad transportation industry

goals and objectives.

To learn more about the EAR Program, visit the Exploratory Advanced

Research Web site at www.fhwa.dot.gov/

advancedresearch. The site features information on research solicitations, updates

on ongoing research, links to published

materials, summaries of past EAR Program events, and details on upcoming

events. For additional information, contact

David Kuehn at FHWA, 202-493-3414

(email: david.kuehn@fhwa.dot.gov), or

Terry Halkyard at FHWA, 202-493-3467

(email: terry.halkyard@fhwa.dot.gov).

Increasing Highway Throughput 

Communications and Control Technologies to Improve Traffic Flow

Learn More

For more information on this EAR project, contact Bob Ferlis, FHWA Office of Operations

Research and Development, at 202-493-3268

(email: robert.ferlis@fhwa.dot.gov).

Publication No. FHWA-HRT-09-037

HRTM-04/03-09(1M)E