Idaho Storm Warning System II

Publication Date


Type of Culminating Activity


Degree Title

Master of Science in Engineering, Computer Engineering


Electrical and Computer Engineering

Major Advisor

Joe Hartman


Interstate 84 is the major passenger and commercial travel route between Boise, Idaho, and Salt Lake City Utah. The stretch between Rupert, Idaho and Tremonton, Utah has experienced a large number of serious accidents and the Idaho Transportation Department (ITD) has been studying methods to reduce the number of accidents. An initial study, Idaho Storm Warning System I (Operational Test), was conducted between 1993 and 2000 to determine if the information from visibility sensors along the highway, conveyed to motorists via Dynamic Message Signs (DMSs), would reduce vehicle speeds to safe levels as warranted by weather conditions [1].

The work in this thesis, Idaho Storm Warning System II, is based on the results of the previous study and five years of accident data (1997-2001). Idaho Storm Warning System II includes:

  • Institution of a variable speed limit (VSL) zone
  • Integration of the system according to national standards

In Idaho Storm Warning System II, instead of allowing the motorists to set their own reduced speed limit as a method of reducing accidents, the weather information may be used to set reduced speed limits and convey this information to motorists using Variable Speed Limit Signs (VSLSs). The location of the proposed VSL zone is a 12- mile segment where the crash rate has been highest. Eight VSLSs are used. Although highway visibility conditions are the major consideration in setting the VSL zone, other conditions such as the road surface and the wind speed also affect driving conditions. The logical effects of the variable weather and road conditions on the safe speed limit at any time may be taken into account using a fuzzy logic algorithm. In this thesis, a simulation was made to determine if the fuzzy logic algorithm would work for the VSL zone with three inputs and one output. It was concluded that application of fuzzy logic works well to set the variable speed limit. National Transportation Communications for Intelligence Transportation System protocol (NTCIP) standards are used to design the system. The protocol for all equipment is suggested to be "Transport Control Protocol/Internet Protocol (TCP/IP)" for efficient integration of the system and to have high reliability. Factors considered in the design of the communication system are minimum data size, long range transmission, and cost effectiveness with high reliability. Spread spectrum communication is suggested for use between the Cotterel Port of Entry (POE) and equipment at the VSL zone. Cellular communication is suggested between the Cotterel POE and DMSs.

Institution of a VSL zone would he1p the driver to reduce driving speeds during severe weather conditions. Integrating the system will reduce maintenance time and cost. ITD personnel could provide important information to the drivers using the DMSs.

Idaho Storm Warning System II is feasible system. The capital cost of the system is $920,000. This is a reasonable cost to reduce a large number of accidents.

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