Road Weather Information Systems (RWIS) typically consist of sensors, remote processing units (RPU), central processing units (CPU), communications equipment, computer workstations, RWIS software, and links to data acquisition services such as the National Weather Service and other meteorological services. A typical RWIS uses pavement sensors to detect ice and atmospheric sensors to measure air temperature, relative humidity, wind direction, wind speed, visibility, and the presence of precipitation. One central unit can support multiple remote sensing sites. Data from these systems assist highway agencies and maintenance personnel enabling them to better manage resources during weather emergencies.
In Abilene, Texas, the state DOT implemented a Road Weather Information System (RWIS) at the intersection of Interstate 20 and milepost 260. This location was selected because it freezes often and is representative of the weather conditions in and around the Abilene area. The RWIS data collected at the site will be used to forecast pavement conditions up to 24 hours in advance thus allowing the Abilene TxDOT maintenance office to manage winter maintenance activities more efficiently. The RWIS consists of one RPU equipped with a modem, two pavement sensors, one subsurface temperature probe, multiple atmospheric sensors, and one CPU equipped with RWIS software. The total cost to purchase and implement system was $42,010 (1997). RPU and CPU costs were $6,446 and $4,000 respectively. The RWIS life cycle is estimated at 25 years; with RPU and CPU replacement needed every five years to stay current with technology. The average annual O&M cost for the maintenance contract was $5,460 (1997) per roadside (remote) site. O&M costs included sensor calibration, equipment repairs, parts replacement, long distance telephone charges, and the cost of meteorological services.
The RWIS economic model presented in the source paper is a synthesis of cited results and data from multiple agencies acquired over several years. The model is used as a decision making tool by transportation agencies for individual and networked RWIS investment decisions. The model is used to quantify the costs and benefits associated with a RWIS implementation and to calculate the net present worth of a RWIS deployment. The net present worth of one installation can be compared against that of other alternatives to aid in the prioritization and decision making process. For the Abilene implementation, the net present worth was estimated at $923,000 (1997) over a 50-year life cycle. Given that the net present worth of the do nothing scenario is set to zero, the Abilene RWIS implementation would be a cost-effective alternative to doing nothing. Likewise, the net present worth of other RWIS installations could be compared with that of Abilene to determine which RWIS implementation to implement.
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System cost: $42,000 (1997). Annual O&M cost: $5,460 per remote site (1997).