2.11 Road Weather Management

Adverse weather conditions pose a significant threat to the infrastructure and operation of our nation's roads. The Road Weather Management Program, within the FHWA Office of Operations, seeks to better understand the impacts of weather on roadways, and promote strategies, tools, and technologies to mitigate those impacts. The program is working to promote a national road weather observing system, enhance decision support for winter maintenance personnel, and advance weather-responsive traffic management. Figure 2.11.1 depicts the classification of benefits and costs data associated with Road Weather Management.

ITS applications that assist road weather management support four major types of activities. Surveillance, monitoring, and prediction of weather and roadway conditions enable the appropriate management actions to mitigate the impacts of any adverse conditions. Information dissemination technologies help road weather managers notify travelers of adverse conditions they may face on their trips. Traffic control measures may be enacted to improve traveler safety under poor weather conditions; a variety of technologies allow these control measures to be taken quickly in response to developing adverse weather. A variety of ITS applications are being deployed in the United States to support roadway treatments necessary in response to weather events. These applications may provide for automated treatment of the road surface at fixed locations, such as anti-icing systems mounted on bridges in cold climates. They may also enhance the efficiency and safety of mobile winter maintenance activities, for example, through automatic vehicle location on snow plows supporting a computer-aided dispatch system.

Table 2.11.1 provides information on the benefits and costs of road weather management. An assessment of the impact of these systems is indicated by using the symbols in the Impact Legend at the bottom of each page.

Table 2.11.1 – Benefits and Costs of Road Weather Management

Surveillance, Monitoring, and Prediction

Benefits
Goal Area	# of Studies	Impact	Example
(New) Customer Satisfaction	2	+	In interviews following the deployment of two new environmental sensor stations (ESS) equipped with pole-mounted CCTV cameras and sensors to measure an array of environmental conditions, the Washington State DOT road maintenance crews ranked pavement conditions data as the most useful ITS technology deployed, followed by camera images, and radar data on the Internet. The maintenance superintendent reported that the ESS data and camera images helped staff become more productive by allowing them to check road conditions in outlying areas and minimize unnecessary trips.[20]
Costs
Unit Costs Database	Roadside Detection subsystem Transportation Management subsystem Roadside Telecommunications subsystem		See Appendix A
(New) System Cost	In 2003, the Ohio Department of Transportation (ODOT) expanded its Roadway Weather Information System (RWIS) with the addition of 86 environmental sensor stations to the 72 already in operation. The 158 ESS provide coverage of all 88 Ohio counties, making it the largest deployment of RWIS in the U.S. Eighty-six ESS have been installed with two more sites going operational in the following construction season. Information from the ESS is processed by a central server located in Columbus. The data are used by ODOT garages for treatment of roads during snow and ice conditions. The deployment was contracted as a product purchase wherein the vendor was responsible for equipment installation. ODOT required that the ESS be compliant with National Transportation Communications for ITS Protocol (NTCIP) and support wireless communication. The contract also includes a two-year service agreement (recurring costs over two years) for maintenance support 365 days a year, 24 hours a day, and 7 days a week, with penalties imposed for down sites.[137]		Cost of 88 additional ESS including training and warranty/service agreement: $3.699 million (2003)
(New) System Cost	A fog detection system is being planned in response to a serious multivehicle accident that occurred in May 2003 along I-68 near Big Savage Mountain in Maryland. The new system will make use of existing infrastructure at two locations and includes a new RWIS. The existing RWISs at Big Savage and Keysers Ridge will be modified to identify low visibility conditions and alert drivers via warning signs. The third location, Friendsville, will be equipped with an RWIS and warning signs.[138]		Costs to modify Big Savage and Keyser sites: $75,000 per location Cost of new infrastructure at Friendsville: $125,000
(New) System Cost	In order to better manage hurricane-related evacuations, the Louisiana Department of Transportation and Development (LA DOTD) worked with the United States Geological Survey (USGS) to deploy Information Stations. Information Stations are USGS Hydrowatch stations that are fitted with traffic count detectors. Information Stations gather and transmit in real time data on traffic and water level conditions along evacuation routes. The costs of these systems vary depending on factors such as retrofitting existing equipment, leveraging joint agency deployments, and sharing operating costs.[139]		Information Station deployment cost: $26,000 (approx.) Information Station annual operations cost: $14,000 (approx.)

Information Dissemination

Benefits
Goal Area	# of Studies	Impact	Example
Safety	6	+	An Idaho DOT study found significant speed reductions when weather-related warnings were posted on dynamic message signs. During periods of high winds and snow-covered pavement, vehicle speeds dropped by 35% to 35 mph when warning messages were displayed, compared to a 9% drop to 44 mph without the dynamic message signs.[140]
(New) Customer Satisfaction	1	+	Ninety-four percent of surveyed users of a road weather information website covering roadways in Washington state agree that the weather information made travelers better prepared for their trips. More than half of the respondents (56%) agreed the information helped them avoid travel delays.[20]
Costs
Unit Costs Database	Roadside Telecommunications subsystem Roadside Information subsystem Remote Location subsystem Personal Devices subsystem Transportation Management Center subsystem		See Appendix A
(New) System Cost	Washington State Department of Transportation (WSDOT) installed a system in the rural and mountainous region of Spokane to collect and communicate weather and road conditions, border crossing status, and other information to commercial drivers, the motoring public, and WSDOT maintenance crews. As part of this system, two ESS were installed at Sherman Pass and the town of Laurier, and two mobile HAR systems were installed near the town of Republic and at the town of Kettle Falls. Broadcasts warn motorists of road construction, incidents, dangerous driving conditions and restrictions, and border crossing conditions and closures.[20]		Two ESS: $45,000 each HAR cost: $111,073 – Two mobile HAR: $52,000 – Signs, connectivity, clearing and other associated costs: $59,073

Traffic Control

Benefits
Goal Area	# of Studies	Impact	Example
Safety	5	+	A variable speed limit system implemented along Interstate 75 in Tennessee to control traffic during foggy conditions, and close the freeway if necessary, has dramatically reduced crashes. While there had been more than 200 crashes, 130 injuries, and 18 fatalities on this highway section since the interstate opened in 1973, a 2003 report notes that only one fog-related crash has occurred on the freeway since installation of the system in 1994.[141]
Mobility	1	0	An investigative study sponsored by the Minnesota Department of Transportation (Mn/DOT) found that optimizing traffic signals along an arterial corridor to accommodate adverse winter weather conditions yielded an 8% reduction in delay. The study also noted that the existing signal timing plans were sufficient to accommodate the lower traffic volumes and lower speeds during winter weather.[142]
Customer Satisfaction	1	?	Survey results in Finland indicate that 90% of drivers found weather-controlled variable speed limit signs to be useful.[143]
Productivity	2	+	The Mn/DOT uses mainline and ramp closure gates to close segments of freeways during severe weather. During a 1998 storm, closure allowed Interstate 90 to be cleared 4 hours earlier than nearby Highway 75, with I-90 clearance costs 18% lower than those for Highway 75.[144]
Costs
Unit Costs Database	Roadside Telecommunications subsystem Roadside Control subsystem Roadside Detection subsystem Roadside Information subsystem Transportation Management Center subsystem		See Appendix A
System Cost	Washington State DOT implemented Travel Aid, a variable speed limit (VSL) system that changes as the weather does, along the Snoqualmie Pass (I-90) east of Seattle. Approximately 13 miles are operated as VSL during the winter months. The system consists of radar detection, six weather stations, nine dynamic message signs, and radio and microwave transmission systems.[53, 77, 78]		Design and implementation cost: $5 million (1997)

Response and Treatment

Benefits
Goal Area	# of Studies	Impact	Example
Safety	3	?	In Minnesota, the Mn/DOT installed an automated anti-icing system on a 1,950-foot (594-meter), eight-lane bridge near downtown Minneapolis on I-35. In the first year of operation, the system significantly improved roadway safety through a 68% decline in winter crashes, when compared to prior winters with comparable weather.[141]
Productivity	6	+	The Wisconsin DOT has found that a snow forecasting model combined with ice detection systems help improve planning for work schedules, reducing labor-hours up to four hours per person during a significant storm.[145]
Costs
Unit Costs Database	Roadside Detection subsystem Roadside Control subsystem Roadside Telecommunications subsystem Transportation Management Center subsystem		See Appendix A
System Cost	The Southeast Michigan Snow and Ice Management (SEMSIM) project is a multiagency automatic vehicle location (AVL) system that will use 500 highway maintenance vehicles equipped with Global Positioning System (GPS) receivers and sensors to monitor snow plow use, rate of application for de-icing materials, and air and road temperatures. In 2002, the system cost approximately $1.862 million to equip 292 vehicles. The system included the development, manufacturing, testing, and integration of software and hardware components (vehicle logic unit, mobile data terminal, sensors, bracket and wiring harness), and communications. Each vehicle will use 900 MHz communications and transmit data to a centralized system where the data will be uploaded onto an Internet server and made available to other agencies. As of November 2003, 375 vehicles were operational.[13]		AVL/GPS system cost: $1.862 million (2002)
System Cost	To address weather-related accidents on a section of I-90 near Vantage, Washington, the Washington State DOT assessed the benefits and costs of deploying an automated anti-icing system to prevent the formation of pavement frost and black ice and to reduce the impact of freezing rain. The proposed installation consists of a liquid chemical storage tank, a pump, a dispensing system with spray nozzles, an ESS, a computerized control system, and a CCTV camera for remote viewing. The system monitors weather and road condition data from the ESS, and automatically activates the dispensing system when pre-determined conditions exist. The system also alerts dispatchers and the maintenance supervisor when the anti-icing system is activated.[146]		Initial cost estimate: $599,500 (1999) Annual O&M costs (estimated): $32,800 (1999)

Table of Contents | Previous | Next

ITS Home | US DOT Home | Privacy | Feedback

United States Department of Transportation - ITS