Federal Highway Administration Resource Center

Transport, Weather, and Technology Communities Gather at National Highway Visibility Conference

Imagine that you are making your daily commute, when you come upon a large patch of fog. You reduce your speed and carefully enter a sea of white.

Suddenly, without warning, you see brake lights ahead of you. Although you try to stop, you are not able to avoid rear-ending the vehicle ahead of you. As you sit and try to calm yourself, your car is hit from behind, and then again from the side. Your car begins to spin, and metal begins crunching and bending around you. As the collisions continue, you can only hold on and hope for the madness to end. Each second feels like an eternity.

Moments of silence pass until at last a rescue worker releases you from the mangled wreckage. You ask yourself as you look over the field of rubble and carnage, “How did this happen?”

On May 18-19, the transportation, weather, and technology communities came together at the University of Wisconsin for the 2004 National Highway Visibility Conference to discuss mitigation strategies for low visibility conditions, highway safety and mobility in low visibility conditions, low visibility warning systems, road weather management program activities, and future steps to address these issues. It has been eight years since the last such conference.

The technology transfer of best practices is important to the safety and growth in transportation. The conference helped advance these goals by bringing together the National Weather Service, NOAA, State DOTs, and private vendors.

The conference, which was sponsored by the Federal Highway Administration, Wisconsin Department of Transportation, AAA Wisconsin, the Midwest Regional University Transportation Center, Wisconsin Traffic Operations and Safety Laboratory, and Wisconsin ITS Alliance, featured new technologies, experts from around the world, and breakthroughs to prevent tragic crashes. The primary goal of the conference was to establish a framework for advancing visibility-oriented technology, State/Federal programs, and an on-going national dialogue.

The conference was prompted by an October 11, 2002 crash on Interstate 43 in Sheboygan County, Wisconsin. That crash involved 50 cars, killing 10 people and injuring 39 others, including 8 serious injuries.

Strategies to Deal With the Challenge of Fog
When fog occurs on the roadway, visibility distance is hindered. This in turn impacts traffic flow through automobile speed, which leads to increased speed variance between drivers, delayed travel time and ultimately increased collision risk. The operational impacts of fog hinge on driver capabilities/behavior, road treatment strategy, access control, and speed limit control. Some possible methods of dealing with low visibility conditions include advisory, control and treatment strategies.
 
Advisory strategies provide information on predicted and prevailing conditions. Control strategies regulate traffic flow and roadway capacity. Treatment strategies supply resources to roads to mitigate weather impacts.

The benefits of road weather management strategies include improved safety due to reduced crash risk, increased mobility due to restored capacity, reduced delays, and more uniform traffic flow. Other benefits include increased productivity due to reduced labor, treatment material, and equipment costs.

GIS Technology
Another technological system discussed at the conference is the Geographic Information System (GIS). Ultimately GIS is another strategy to improve travel in low visibility conditions.

A number of State DOTs presented technology systems being used in their States. These presentations played a pivotal role informing other States of existing solutions to the visibility problems. Before the solutions, came tragic stories, and after the solutions, came successes. A number of States such as Alabama, California, South Carolina, Tennessee, and Utah presented their warning systems.

In a 4-year period before their low visibility warning system was installed, 19 fog-related crashes occurred on the freeways in the Stockton-Manteca area of San Joaquin County, California. The freeways in this particular area are prone to low visibility conditions. Visibility is reduced by wind-blown dust in the summer and dense fog in the winter. Because of such events, Cal. DOT, also known as Caltrans, implemented an automated system to warn motorists of driving hazards.

Since its implementation in November of 1996, there have been no fog-related crashes in the Stockton Manteca area. This is a drastic change from the 19 crashes that occurred during the four year period before the system was deployed. Similar results have been experienced in South Carolina.

The decision support software for the central computer predicts or detects foggy conditions, correlates environmental data with predetermined response strategies, and alerts traffic managers in the district office. Operators may accept or decline response strategies recommended by the computer system. Potential advisory and control strategies include displaying pre-programmed messages on DMS, illuminating pavement lights to guide vehicles through the fog, extinguishing overhead street lights to minimize glare. Other, more drastic strategies include closing the freeway and detouring traffic to Interstate 26 and US Highway 17, or informing Highway Patrol officers to erect barricades to close the freeway.

The outcome of this system enhanced mobility by providing traveler information and clearly separating travel lanes with pavement lights. Furthermore, no fog-related crashes have occurred since the system’s deployment.

Due to high traffic volumes and local conditions prone to dense fog formation, the Utah DOT deployed a low visibility warning system on Interstate 215 to inform motorists of safe travel speeds and to promote more uniform traffic flow. The system has been installed on a two-mile strip of highway located above the Jordan River in Salt Lake City where multi-vehicle, fog related crashes have occurred.

The outcome of this system showed that overly cautious drivers sped up when advisory information was displayed, which resulted in a 15 percent increase in average speed from 54 to 62 mph. This particular increase caused a 22 percent decrease in speed variance from 9.5 to 7.4 mph. This reduction in speed variance improved mobility and safety by promoting more uniform traffic flow and minimizing the risk of initial, secondary and multi-vehicle crashes.

For each of the presenting States, successes were encountered when using the low visibility warning systems. The successes in each of the States were not only important to the lives of travelers within the respective States, but also to the lives of travelers within the nation. This particular conference not only spread the word of success to other States, but also spread the aims and activities of the Road Weather Management Program to all who attended.

During the fog-related 2004 National Highway Visibility Conference it was conveyed to those attending, that a partnership was developed between the National Oceanic and Atmospheric Administration (NOAA) and the Federal Highway Administration (FHWA). The Road Weather Management Program also promoted new tools and technologies such as the Nationwide Surface Transportation Weather Observing System and Weather-Responsive Traffic Management. The Road Weather Management Program has developed outreach and training materials through best practices for Road Weather Management and Intelligent Transportation Systems (ITS) standards. As discussed during the conference it is obvious that the Road Weather Management Program members have been working exhaustively towards their goals.

The success of this conference can be measured at this time by the relationships forged between States and partnerships created between organizations. “They had a good cross-section of involvement, including engineers, RWIS people, DOT people ...,” says Charlie Ginnocchio, southeast region manager of ADDCO.

“I think they brought together a good group of people with relative expertise and good discussions,” says Dr. Amanda Staudt, Board on Atmospheric Sciences and Climate National Research Council/National Academies.

For more information, contact:

Ray Murphy
ITS Specialist
Operations Technical Service Team
FHWA Resource Center, (708) 283-3517
ray.murphy@fhwa.dot.gov

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