Weather Applications > Weather Forecasting

What is it?

• National Differential GPS (NDGPS), predictive computer models, monitoring station networks, and Road Weather Information Systems (RWIS) are all weather forecasting technologies. Most of these technologies incorporate an instrument that measures atmospheric water vapor and air as well as water temperatures, which are all significant indicators of forthcoming weather.

• Most weather forecasting technologies also disseminate weather forecast information to drivers via Traffic Management Centers (TMC), Highway Advisory Radio (HAR), or wireless phones. Some of these technologies also detect weather or have road maintenance capabilities. See our Telecommunications Diagrams on Weather Forecasting for more information.

Key Results

• Weather forecasting technologies can predict weather consditions with great accuracy and detail (i.e. provide hourly weather updates).
• Highway agencies use weather forecasting information to make decisions about the amount of labor, equipment, and materials they will need to respond to forthcoming road weather conditions.
• Drivers are prepared to contend with road-weather hazards, potential delays, and alternative driving routes when they are informed of weather forecasts.
• Weather forecasting technologies were more efficient than human staff at monitoring road conditions.

Benefits

Economic

• Weather forecasting technologies allow for increased management efficiency in costly winter maintenance as well as faster response to weather-related emergencies.
• Highway agencies save by using fewer call-out crews and overtime workers.

Public Safety

• The integration of forecasting and information dissemination technologies significantly enhances the safety and efficiency of surface transportation.
• Real-time weather forecasting information reduces the number of weather-related accidents and deaths and allows for more efficient throughput of traffic during inclement weather.
• There are fewer salts and other chemicals entering the watercourse and soil from anti-icing or de-icing processes.

Costs

• RWIS: Capital Cost: 25k, Operation and Maintenance: 0.4-2.5k per year
• VMS: Capital Cost: 10-50k, Operation and Maintenance: 1.9-4.1k per year
• HAR: Capital Cost: 16-32k, Operation and Maintenance: 0.6-1k per year
• GPS/DGPS: Capital Cost: 0.5-0.8k, Operation and Maintenance: 0.01-0.016k per year

Implementation and Operational Challenges

• Increased resolution of mesoscale atmospheric models is needed to develop more accurate road weather prediction systems.
• There is a need for more effective timing of forecasts and critical temperatures as well as for more accurate estimates of start and end times of storms.
• There is a lack of detailed road weather information such as location-specific road weather data.

Where is it implemented?

Weather forecasting technologies are used throughout the world. There are many currently deployed as well as planned weather systems in the United States. Some of the more sophisticated systems are at work in the Midwestern and Eastern US, where extreme weather conditions greatly affect everyday road travel.

• ATWIS: North Dakota
• FORETELL: across the United States
• Aurora: worldwide
• SAFE-PASSAGE: Illinois and Washington
• RWIS: across the United States
• Tennessee Fog Detection and Warning System: Tennessee
• Anti-ice/De-ice: across the United States
• Snow Removal: across the United States

Case Studies

Advanced Transportation Weather Information System (ATWIS) Research Program

System Description: The primary purpose of the ATWIS research program is to demonstrate how current technologies in weather forecasting, weather analysis, telecommunications, and road condition monitoring can be merged effectively to produce a safer and more efficient transportation system. The program demonstrates a prototypical advanced weather information system including a management center to support traffic weather analysis and forecasting in a responsive decision support environment.

The Advanced Transportation Weather Information project began in 1996 with the aim of providing route-specific short-range weather and road conditions to the traveling public and commercial vehicle operations. Cellular and wireless phone users can dial #7233 (#SAFE) along any Interstate, US, or state highway within North Dakota, South Dakota, and Minnesota.  After answering a few questions detailing their location and direction of travel, the caller is provided a road condition report and short-range weather forecast.

Results: The University of North Dakota conducted a study (1997-1998) to evaluate the use of ATWIS. The study showed that less than half the population surveyed was aware of the existence of #SAFE. Ten percent (10.5%) of all persons surveyed reported using the #SAFE. Following radio/TV advertising, highways signs were the most frequent way people reported becoming aware of #SAFE. Transportation Department maintenance crew supervisors were almost all daily users of weather information. Most used the forecasts for planning their activities, and they found the forecasts accurate. A majority (75%) said they had altered their assignment of personnel as a result of the daily forecast.

Source: ATWIS

National Differential GPS

The National Oceanic and Atmospheric Administration (NOAA) Forecast Systems Laboratory and Federal Highway Administration (FHWA) have initiated a joint project to investigate the use of National Differential Global Positioning System (NDGPS) sites for improved weather forecasting. The NDGPS is an augmentation to the Global Positioning System (GPS) and combines the navigational applications of GPS with meteorological remote sensing to measure atmospheric water vapor. As such, NDGPS is a useful tool for making accurate weather forecasts. It is also linked to cell phones to alert travelers and emergency personnel of adverse weather conditions.

System Description: NDGPS includes an NDGPS tower, water vapor sensors, and mobile receivers. The fixed location of an NDGPS tower is compared to the GPS-determined location of the tower. The measured difference between the actual location and the GPS location can be used as a correction factor. This factor or "signal" is transmitted to hand-held or in-vehicles mobile receivers. These receivers use the corrective signal to adjust the GPS location so that it becomes the more accurate NDGPS location. The closer the receiver is to the transmitter, the more accurate the correction and thus the adjusted location. NDGPS also measure the slowing of satellite signals by water vapor with great accuracy.

Sources: National Differential GPS, Nationwide Differential GPS Water Vapor Observations During Hurricane Georgest, James, Arnold. New Applications make NDGPS more pervasive. Public Roads. January/February 2001.

FORETELL Field Operational Test

System Description: FORETELL collects, forecasts, and distributes highly specific road weather information that is pertinent to highway and trucking professionals, transit operators, everyday commuters, long-distance travelers, and all other road users.

FORETELL is a multi-state initiative covering the Upper Mississippi Valley region funded in part by the Federal Highway Administration (FHWA). The mission of the FORETELL field operational test is to create a road weather information system (RWIS) fully integrated within a wider set of Intelligent Transportation System services to enhance safety and facilitate travel throughout North America. Information provided by this system will be disseminated to the Iowa DOT and eventually be made available to other agencies and to the public via a variety of means such as: Highway Advisory Radio, Variable Message Signs and the Internet.

Source: FORETELL

Aurora

System Description: Aurora is a long-term program of collaborative research, development, and deployment of advanced technologies for detailed road and weather monitoring and forecasting. Aurora programs integrate road and weather technologies with weather monitoring infrastructures in order to forecast weather and provide real-time information to travelers. There are currently 5 completed Aurora projects and 16 on-going projects. One of Aurora’s completed projects is the Standardized Testing Methodologies for Pavement Sensors-Phase I. The purpose of this project was to establish and evaluate standard procedures for testing RWIS sensors, related software, and models. Phase I was aimed at identifying worldwide efforts to test and calibrate road weather sensors. This project determined that Aurora’s size and resources are not sufficient to fund an independent effort to develop test and calibration standards. A Phase 2 for this project has been funded and is aimed at finding ways to promote the development of national and international RWIS standards and procedures.
Source: Aurora Program Home Page

SAFE-PASSAGE Project

System Description: The project employs technology to develop a predictive computer model to micro-forecast pavement temperatures and roadway conditions; provide real-time motorist information; and establish a rural traffic management center for reception, coordination, and dissemination of all relevant data. The SAFE-PASSAGE project is located on Interstate 90, a major east-west corridor between Chicago, Illinois and Seattle, Washington.

The system will also enable maintenance personnel to improve the timing of deicing chemical applications in this high elevation mountain pass corridor. The predictive model will be integrated with several traditional rural technologies including Road and Weather Information Systems (RWIS), Variable Message Signs (VMS), Highway Advisory Radio (HAR), a Rural Traffic Management Center (RTMC), and Rural Advanced Traveler Information System (Rural ATIS).

Source: SAFE-PASSAGE

RWIS Programs

System Description: A Road Weather Information System (RWIS) uses historic and current climatological data to develop real-time road and weather information (i.e. forecasts) for roadway users. RWIS use specialized equipment and computer programs to monitor air and pavement temperatures in order to predict whether precipitation will freeze on the pavement. Sensors collect real-time data on air and pavement temperatures, precipitation, and the amount of deicing chemicals on the pavement. These are combined with information from value-added meteorological services to predict pavement temperatures for a specific area, such as a mountain pass, over a 24-hour period. These predictions are then transmitted to a computer at the highway agency's winter maintenance center. This information is critical to an effective anti-icing strategy, since deicing chemicals must be applied about an hour before the pavement reaches freezing temperatures. This prevents ice from forming on the pavement, in contrast to traditional methods in which the ice is cleared after it has already bonded to the pavement. Using portable computers linked by modem to the central computer, maintenance managers can monitor conditions and advise motorists and dispatch crews as necessary.

Source: RWIS

Tennessee Fog Detection and Warning System

In December 1990, a chain-reaction collision involving 99 vehicles prompted the design and implementation of a fog detection and warning system on Interstate 75 in southeastern Tennessee. The system covers 19 miles including a three-mile, fog-prone section above the Hiwassee River and eight-mile sections on each side.

System Description: Center managers with the Tennessee DOT and Tennessee Highway Patrol access a central computer system that collects data from eight fog detectors, and 44 vehicle speed detectors. By continually monitoring fog and speed sensor data, the computer system predicts and detects conditions conducive to fog formation, and alerts managers when established threshold criteria are met. Highway Patrol personnel visually verify onsite conditions.

The computer system provides decision support by correlating field sensor data with pre-determined response scenarios. Operational techniques include advising motorists of prevailing conditions via flashing beacons atop six static signs, two Highway Advisory Radio (HAR) transmitters, and ten Dynamic Message Signs, reducing speed lim using ten VSL signs (i.e., 50 mph or 35 mph), and restricting access to the affected highway section with ramp gates under the worst-case scenario (i.e., visibility less than 240 feet).

Results: There have been over 200 crashes, 130 injuries and 18 fatalities due to fog on this highway section since 1973. Since the installation of the fog detection and warning system in 1994, no fog-related accidents have occurred.

Source: Tennessee Fog Detection and Warning System

Author: Lauren Smith