Environmental Sensor Station
Weather information systems (WIS) consist of the hardware, software and communications interfaces necessary to provide real-time information on weather conditions to transportation agencies and their customers. They provide data on road, tidal/offshore and other weather-related conditions. WIS includes satellite weather information, environmental sensor stations (ESS) that use atmospheric sensors, pavement and sub-surface sensors, and water-level sensors to monitor weather conditions. Information gathered is then sent to traffic managers, information service providers (ISPs), dynamic message signs, emergency personnel and other environmental monitoring networks.
A transit agency’s bus, para-transit, van, and rail lines can be adversely affected by weather conditions. Transit agencies can either implement their own WIS or sometimes they can access existing WIS and weather networks such as the National Weather Service. Sharing information with transit agencies allows them to make intelligent decisions regarding how they are going to respond to weather-related conditions. For instance, a transit agency with a ferry service may receive marine weather advisories and reroute traffic to land-based transportation.
Weather impacts the nation’s roads and accounts for 7,000 fatalities, 800,000 injuries and $42 billion in economic costs each year1. Drivers endure over 500 million hours of delay due to fog, snow and ice. It also significantly impacts offshore marine, air traffic and rail operations. Every mode of transportation is affected by the weather and may benefit from increased ability to receive, analyze and disseminate weather-related information.
To reduce the impact of adverse weather conditions on surface transportation users, in 2004 the U.S. Department of Transportation (DOT) Road Weather Management Program established the Clarus Initiative. The goal of this initiative was to integrate a data collection, quality-checking and data-dissemination system that could provide near real-time atmospheric and pavement information. The data collected includes information from: road weather information systems (RWIS), environmental sensor stations (ESS), and mobile observations from AVL equipment installed in vehicles. The overall objective of Clarus is to provide information to transportation managers and travelers to manage the effects of driving in adverse weather.
Another road weather management program sponsored by the U.S. DOT is the Maintenance Decision Support System (MDSS). MDSS is a decision support tool that integrates relevant road weather forecasts, maintenance rules of practice, and maintenance resource data to provide winter maintenance managers with recommended road treatment strategies. MDSS is more effective, and therefore more prevalent, as a state DOT application than as a transit agency application.
Clarus User Needs Diagram
The Road Weather Connected Vehicle Applications (RWCVA) are the next generation of applications and services that assess, forecast, and address the impacts that weather has on roads, vehicles, and travelers. These applications build on the Clarus Initiative, which delivered an integrated network of road weather information. Through additional research, technology development, and community outreach, RWCVA will develop specificity regarding the impact that weather has on roadways and promote strategies and tools that mitigate those impacts. The vision for the RWCVA research is to broaden road weather data to include mobile sources and to improve the ability to detect and forecast road weather and pavement conditions by specific roadway links.
The RWCVA Program seeks to:
- Improve safety by reducing crash risks due to inclement weather, increase awareness among agencies and users of the real-time conditions, and restore safer driving conditions more quickly and efficiently.
- Increase mobility by restoring capacity, reducing delays, and creating more uniform traffic flow.
- Increase productivity and reduce operation costs by optimizing the use of labor, pavement treatments, and equipment.
1 Weather Information for Surface Transportation Report
As with electronic fare payment (EFP), weather information systems are generally deployed as a stand-alone technology that communicates with the central transit management center (TMC). Using pavement sensors installed on transit vehicles, automated vehicle location (AVL) technology can be used to report pavement conditions to dispatchers in the TMC. Dispatchers can use this information to communicate route-changes, emergency responses and other messages to their drivers. Transit Communications Interface Protocols (TCIP) practices and protocols should be used when integrating systems together into the TMC central software.
Factors to Consider
Weather information systems can provide benefits to an agency of any size. However, system implementation costs can be high and they may be difficult to finance for smaller or rural agencies. Transit agencies may find that developing networks with other agencies that desire or use weather-related information can be an effective cost-mitigation strategy. If an agency only requires basic data, obtaining access to satellite-based information may be sufficient to meet their needs. WIS seeks to take existing weather detection, computer, and communications technologies and apply in them in an integrated way to increase the safety and efficiency of road transportation.
MTA Weather Sensor installed on a light pole
- Develop a structured procurement plan and performance-oriented requirements and specifications.
- Involve staff from various departments and outside stakeholders, such as contractors that may provide transportation or weather services or may be (eventually) linked to the transit agency service and WIS network.
- Visit transit agencies (or non-transit agencies) providing similar transportation or weather information services and discuss their WIS systems and related technologies.
- Perform rigorous testing of the entire system to identify areas where more WIS tools/coverage are needed.
- Consider installing backup systems to ensure undisrupted communications and data storage in case of failure by the main network.
- Develop standard data-exchange protocols using TCIP in order: to allow the use of equipment from multiple vendors; to operate on different bandwidths; and to communicate with different technologies.
- Equip all systems with virus and firewall protection.
- Expect learning curves as customers and agency staff transition to WIS and various response scenarios.
- WIS can be independent or integrated with other related intelligent transportation systems (ITS). However, equipment from multiple vendors and among different regional area transit agencies may require special attention when planning and integrating a new WIS system.
- Transit systems associated with WIS should be linked with the communications networks used by information technologies.
- WIS requires a power supply and communications system such as fiber optic cable or wireless to provide data remotely to the TMC.
Benefits and Costs
Implementing a WIS can improve a transit system’s overall performance during weather events by:
- Reducing agency costs for weather-related maintenance and operations activities.
- Reducing the number of crashes attributed to adverse weather.
- Reducing transit delays due to fog, snow, and ice events.
Equipment and Implementation
Heat kinks in rail tracks due to extreme heat
WIS vary in cost depending on the number of pavement sensors and the type of weather instrumentation included with the weather station and the central software. Stand-alone software will be less costly than integration of the WIS software with existing TMC software.
An entry-level WIS site would cost around $20,000 for the equipment and the installation costs vary between $15,000 and $20,000.
Operations and Maintenance (O&M)
A transit agency would work with their state DOT to access WIS information. This would be done through remote communication connections between control centers to monitor pavement conditions that may affect transit operations. Standard operating procedures can be set up between the transit operator and the state DOT to share road condition information.
Transit agencies monitor the National Weather Service for extreme weather conditions, such as snow, ice, fog, flooding, severe heat/cold, or high winds and adjust transit operations accordingly.
Extreme heat can cause kinks or buckles in rail tracks, which can lead to train derailment. Additional track inspectors may be needed to monitor tracks for this condition during periods of extreme heat.
Various web-based training courses on road weather management sponsored by FHWA are available at https://ops.fhwa.dot.gov/weather/.