Browsing by Subject "Light emitting diodes"

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    Advanced LED Warning Signs for Rural Intersections Powered by Renewable Energy
    (Minnesota Department of Transportation Research Services Section, 2010-12) Kwon, Taek Mu; Weidemann, Ryan
    A majority of intersection-related fatal crashes occur at rural, through/stop intersections. At these intersections, sight restrictions caused by vertical and horizontal curves negatively affect a driver’s ability to safely accept a gap in the traffic stream. Static advanced warning signs are sometimes installed at these intersections to warn drivers on the main, through approaches that an intersection is ahead. These warning signs appear to be ineffective. A new Advanced Light-Emitting Diode (LED) Warning System was developed and deployed at a rural, through/stop intersection with limited intersection sight distance due to a severe vertical curve. This warning system actively detects vehicles on all approaches and activates LED blinker warning signs for the conflicting movements. The research project included analysis of driver behavior obtained through video data and a survey of local residents and frequent users of the intersection. This report describes the development, implementation, and evaluation results of this new warning system.
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    Advanced LED Warning System for Rural Intersections: Phase 2 (ALERT-2)
    (Minnesota Department of Transportation, 2014-02) Kwon, Taek M.; Ismail, Husam
    This report presents findings of the second phase of the Advanced LED Warning System for Rural Intersections (ALERT) project. Since it is the next generation of the same system, the second phase system is referred to as the ALERT-2 system while the first system is referred to as the ALERT-1 system. The ALERT systems demand use of four basic Intelligent Transportation Systems (ITS) technologies: LED-based signs, renewable energy, non-intrusive sensors, and wireless communication. Use of these four basic technologies remained the same for both phases of the system. In the first phase, the data showed that the ALERT-1 system reduced vehicle speeds on the main approach, increased STOP wait time on minor approaches, and eliminated roll-throughs for vehicles on minor approaches when a conflict existed in the intersection. However, when no conflict exists in the intersection, an increase in roll-throughs for vehicles on the minor approaches was observed. The ALERT-2 system was redesigned to mitigate this increased roll-throughs. With respect to technological advances, the ALERT-2 system improves many aspects of the basic technologies, providing higher system reliability, easier installation and maintainability, and better self-sustainability through redesign of the renewable energy application. To assess the driver behaviors at the test site, 13 moths worth of video data and a survey of local residents were collected. This report describes the system development, implementation, and analysis of the video and survey data.