Weather and Highway Safety

Weather and Highway Safety
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The United States, and more specifically its economy, is highly dependent on the national highway system. More than 200 million cars and trucks use the national highway system and critical parts function at or near their maximum capacity much of the time (OFCM, 2002). About 77% (by weight) of domestic freight shipments are by truck (versus other modes of transportation). Adverse weather, including rain, snow, sleet, fog, etc., can easily reduce roadway capacity and significantly affect the efficiency of this system. Weather also plays a critical role in highway safety. In the United States each year, approximately 7,000 highway deaths and 800,000 injuries are associated with poor weather driving conditions. The estimated annual economic cost from these weather- related crashes (deaths, injuries, and property) amounts to nearly $42 billion (Lombardo, 2000). Weather is a factor in about 28% of the total crashes and 19% of the total fatalities. It is clear that the societal and economic impacts of adverse weather on the highway system are huge.

The traveling public is the ultimate user of the road transportation system. People rely on the system as commuters, tourists, and consumers. In addition, police, fire fighters, school transportation systems, and emergency medical service providers, along with many others, rely on the transportation system to meet the vital needs of the public. Travelers are quite aware of the impact of weather on the roadway system. A Gallup public opinion poll conducted in 2002 indicated that 40% of the potential users of the national “511” system identified weather and road condition as the most important information element (ITSA, 2002). The public clearly understands the relationship between weather and highway safety and congestion, and they seek solutions to enhance mobility.

Given the enormous impact weather has on the highway system and the potentially huge safety and economic benefits that could be realized if weather information was used more effectively by road operating agencies and the public, why has it not received the attention it deserves? What has or has not been done to promote road weather services, what opportunities are emerging, and what impediments are in place that have slowed progress to date? What policies, if any, are needed at the federal and/or state levels?

In an effort to discuss responses to these questions, the Atmospheric Policy Program of the American Meteorological Society (AMS) developed a forum to foster vigorous policy level dialogues. These dialogues led to recommendations on how to improve the safety and operations of the nation’s highway system through better application of weather information. The forum brought together representatives of the weather information providers; transportation managers and users; and policy makers knowledgeable about the nation’s highway system. The representatives were drawn from the public and private sectors at the national, state, and local levels.

The forum took place over a two-day period on 4-5 November 2003 in Washington, DC. It consisted of three panel discussions focused on 1) present and near-term potential in providing weather information to improve the highway system, 2) public and industrial development of strategies to effectively respond to weather information, and 3) policy issues in implementing effective application of weather services to the management of the nation’s highway system. Each panel was followed by a period of discussion leading to recommendations.

The forum discussions led to the following six recommendations, of which two are overarching. All recommendations are directed at improving the safety and efficiency of the roads for the ultimate benefit of the traveling public.


The program should:

• be a multi-faceted interdisciplinary road weather research program focused on addressing the needs of road operating agencies and the traveling public;

• be designed to support the operational decision making process of the traveling public and operational personnel involved in traffic, incident and emergency management, construction, and maintenance activities;

• include technology transfer components that provide mechanisms for the resulting technologies to be applied nationally in a timely manner;

• result in technologies that are consistent with and complimentary to the Intelligent Transportation System (ITS) architecture and framework;

• be designed for drivers and transportation managers to take advantage of and augment current and emerging transportation technologies including intelligent vehicles, telematics, mobile sensing systems, 511 systems, dynamic navigation systems; and

• include mechanisms, such as rapid prototyping and model deployments, to assess user feedback and the potential benefits of the new technologies.

1. Congress should authorize and provide long-term funding for the appropriate federal agencies to develop a national road weather research, development, and applications program, to improve the application of weather information for highway safety and operations.


The coordinated activities should include:

• aggressively reviewing and quickly implementing, where appropriate, currently available weather and ITS technology to highway operations—in particular, technology that responds to weather conditions (e.g., variable message signs, dynamic speed limits, ramp metering, and road condition information kiosks);

• promoting the use and expansion of road weather and road condition measurement and information systems;

• developing and applying national standards for Road Weather Information Systems (RWIS) that include accuracy, data format, and siting requirements; and

• working with organizations (e.g. AAA and AMS) to implement programs of education and public awareness, including effective driver education programs that provide instruction on appropriate driving responses to hazardous weather and better utilization of advanced automotive capabilities.


The infrastructure should be designed to ensure:

• the open two-way exchange of relevant transportation data and practices between weather and transportation industry stakeholders;

• that national standards are established and used for weather, traffic, and road condition measurement systems and that open system formats and protocols (e.g., NTCIP) are adhered to;

• that quality control methods and techniques are applied to the data; •            that it can take advantage of existing weather information and warning technologies (e.g.,

NOAA Weather Radio) and future communication networks (e.g., telematics); and

• that data are collated on a national level and made available centrally on a non-exclusive basis.

2. The federal and state departments of transportation should closely coordinate with public, private, and academic sector road weather stakeholders to improve the safety and efficiency of the nation’s highway system during adverse weather.

3. DOT/FHWA and NOAA, working with state DOTs, should establish a national road weather and road condition data collection, processing, and dissemination infrastructure to improve the safety and efficiency of the roadway system.


Road weather observational and forecast improvements should focus on:

• boundary layer and near-surface meteorology (0-3 meters above ground level) where travelers generally experience road weather hazards (fog, ice, snow, hail, heavy precipitation, blowing snow, etc.);

• collecting and distributing observational data (e.g., ASOS, AWOS, RWIS) with sufficient temporal resolution (minutes) to support tactical decision making;

• distributing weather prediction datasets with sufficient time resolution (hourly), spatial resolution (1-10 km), and data elements needed to analyze and predict pavement conditions;

• road (and bridge) condition prediction models and characterization of the pavement surface; •          developing and implementing probabilistic weather products tailored for the road weather

risk management decision process;

• developing new-generation weather and pavement condition sensors to improve the measurement of parameters critical to support roadway operations; and

• making output (data and products) understandable and relevant for highway decision makers and the traveling public.


Training and education programs should:

• be focused on educating transportation decision makers (traffic, incident, and emergency management, construction and maintenance personnel) and the automobile industry to improve their understanding of weather hazards and the impact of those hazards on the transportation system;

• be developed at universities to ensure that an adequate pool of qualified “road weather” meteorologists exists to service the surface transportation community; and

• train weather information providers on the needs/challenges of the surface transportation community.

4. NOAA/NWS, commercial weather providers, and weather information users should work cooperatively to improve the observation system, develop and improve forecasts, and enhance the delivery of information and services on road weather.

5. Federal and state DOTs should train the road management community to more effectively integrate weather into the decision process. In addition, the atmospheric science community, particularly academia, should develop course curricula focusing on road weather science and engineering.


6. DOT/FHWA should provide incentives for vehicle manufacturers and highway engineers to raise public and private sector demand for in-vehicle road weather information.

Specifically, the incentive program should include:

• support for research and development, benefit analyses, and human factors studies of in- vehicle weather and road condition information systems;

• FHWA and state DOT participation in prototyping activities, field demonstrations and model deployments of new in-vehicle information systems; and

• support for the development of promotional campaigns describing the safety and mobility benefits of utilizing in-vehicle weather and road condition information technologies.

Meaningful actions in response to these recommendations will require cooperative efforts by federal, state, and local DOTs; transportation decision makers; academia and research centers; and weather information providers. Leadership by the U.S. DOT, in cooperation with NOAA and NSF, with support from Congress, is vital if these recommendations are to be successfully applied to improve the safety and efficiency of our nation’s roads.