Exploratory Advanced Research . . . Next Generation Transportation Solutions

control, gap-responsive on-ramp signal, and merging 

control. Dynamic lane control encourages lateral 

movements of mainline vehicles by using a lower 

speed limit for the far right lane of the freeway. A gapresponsive on-ramp signal algorithm will give a ramp 

vehicle the green light based on the expected gap 

availability in the freeway mainline. As these algorithms have previously been developed, the project 

will focus on enhancing and refining them. Finally, the 

revolutionary merging control algorithm will control 

and advise speed changes for both mainline and 

ramp vehicles in order to allow for merging in the 

smallest space, at the highest speed possible.

Expanding Research

According to Bob Ferlis of FHWA, “this project provides a comprehensive means to address freeway 

merging. The team at UVA CTS is successfully building on and extending the results of previous ramp 

metering research to deliver improvements in efficiency and driver safety when merging.”

One of the major objectives of this project is to 

utilize the communication capabilities of IntelliDrive. 

The research team plans to integrate microscopic 

transportation simulations with wireless network simulations. It is expected that the results from both simulations will help in designing control actions associated with freeway merging.

A safety evaluation module will also be developed 

to assess safety impacts under various scenarios. 

This module is unique in that it will generate a projected number of crashes. Vehicle trajectories reconstructed from actual crash data will also be investigated to explore drivers’ response time as a 

contributing factor, as well as the potential to prevent 

crashes either by sending an alert to the driver, or 

else by using automated action where drivers would 

not have time to respond themselves. 

Future Benefits

This research has the potential to significantly improve freeway merge areas, which present significant 

The Exploratory Advanced Research Program Fact Sheet

Utilizing IntelliDrive 

IntelliDrive is an initiative designed to enable wireless 

communications among vehicles, the highway infrastructure, and travelers’ personal communications devices. UVA CTS aims to develop and evaluate candidate freeway merge assistance systems that might 

significantly improve operations in an IntelliDrive environment. UVA created an IntelliDrive/Traffic simulation 

tool over a 3-year development process with funding 

from the National Science Foundation, FHWA, and the 

Virginia and California Departments of Transportation. 

Using a previous 2008 study on the ability of 

IntelliDrive to improve ramp metering as the starting 

point for this study, the project team aim to develop 

and evaluate strategic algorithms designed to improve 

freeway merging. These algorithms will be developed 

specifically to take advantage of the capabilities provided by the system. 

Improved Merging Algorithms

The freeway merge assistance system under development will consist of three algorithms: dynamic lane 

One of the major traffic bottlenecks and 

safety concerns on today’s busy roads 

occurs during freeway merges. “Advanced 

Freeway Merge Assistance: Harnessing the 

Potential of IntelliDrive,SM*” is an Exploratory 

Advanced Research (EAR) Program project 

designed to improve the efficiency and safety 

of freeway merges using IntelliDrive. This 

project was awarded by the Federal Highway 

Administration (FHWA) in 2009, and is being 

conducted by the University of Virginia Center for Transportation Studies (UVA CTS).

Efficient and Safe Merging Solutions 

Advanced Freeway Merge Assistance: Harnessing the Potential of IntelliDrive

* IntelliDrive is a service mark of the U.S. Department of Transportation
bottleneck and safety concerns today. The project will 

also help prepare transportation agencies to make full 

use of IntelliDrive technology as it emerges.

“Ultimately the project is expected to create freeway merge areas with greater capacity and fewer 

crashes,” says Ferlis. “The algorithms under development here will continue to take advantage of emerging 

IntelliDrive capabilities to improve the safety and efficiency of future freeway merge operations.”

For vehicle, system, and equipment manufacturers 

to build on these results in the future, additional research will be needed to further develop the concept 

of operations, understand its value, and to identify 

promising deployment scenarios. Success at this stage 

of research could lead to further traffic simulation studies with higher-level controls for the freeway and its 

environs. Also, additional simulations could be conducted using a driving simulator to assess the receptivity of people to advice, or control actions taken in 

response to the concept of operations. Success could 

eventually lead to testing a prototype on a closed 

course to identify further technical questions, assess 

human factors issues, and to support technology transfer activities.

Learn More

For more information on this EAR Program project, 

contact Bob Ferlis at FHWA, at 202-493-3268 (email: 

robert.ferlis@dot.gov).

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).

Publication No. 

FHW-HRT-10-076

HRTM-04/09-10(1M)E

Efficient and Safe Merging Solutions 

Advanced Freeway Merge Assistance: Harnessing the Potential of IntelliDriveSM

Image other side: 

This is a merge sign by the road 

side with sky as background.

©www.istockphoto.com/

zxcynosure

Traffic merging onto freeway.

©www.istockphoto.com/Joe_Potato