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Mid-America Transportation Center

Longitudinal Useful Life Analysis and Replacement Strategies for LED Traffic Indicators

Final Report
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Researchers

  • Principal Investigator: Suzanna Long (longsuz@mst.edu 573-341-7621)
  • Project Status
    Complete
    About this Project
    Brief Project Description & Background
    The project develops a robust, longitudinal methodology for LED traffic indicator useful life assessment and replacement. This project extends a previous study completed by the research team. Collecting data from the same LED traffic indicators over a several year period of time will provide more reliable results to perform regression analysis and increase the level of confidence the analyst would have in the predictions made for replacement strategies. This project is focused on three tasks. The team will develop a test matrix that will evaluate the impact of the following variables: manufacturer, color, directional view, daylight conditions on the gradation of LED traffic signals. These results will be analyzed using the methodology developed as part of the previous study.
    Research Objective
    Our research extends our methodology from TRyy1001 to analyze the rate of degradation of LEDs and develops a robust mechanism to measure their useful lives. This research provides the first replacement recommendations for different types and colors of LED traffic indicators based on actual field performance and regression analysis of a sample population. Data is collected and analyzed from the driver’s perspective to more fully integrate safety into replacement strategies. The longitudinal data will be used to develop more robust replacement schedules based on the useful life of LED traffic indicators currently in use in Missouri.
    Potential Benefits
    LEDs (light-emitting diodes) have been widely adopted for use within traffic signals recently replacing incandescent bulbs. LEDs degrade slowly unlike incandescent bulbs that fail catastrophically. When the luminous intensity of LEDs falls below a pre-specified threshold, they pose danger to traffic. Although considered a more sustainable technology, the long-term performance and degradation rates of LEDs have not been thoroughly studied to gain an understanding of their useful lives and appropriate replacement schedules. There exist many stochastic factors that affect LED degradation rates making their analysis complicated. This research extends a previous cross-sectional study funded by the Missouri Department of Transportation (MoDOT) to provide a much needed longitudinal methodology for engineering managers in departments of transportation and local communities for replacing LED traffic indicators.
    Abstract
    The project develops a robust, longitudinal methodology for LED traffic indicator useful life assessment and replacement. This project extends a previous study completed by the research team. Collecting data from the same LED traffic indicators over a several year period of time will provide more reliable results to perform regression analysis and increase the level of confidence the analyst would have in the predictions made for replacement strategies. This project is focused on three tasks. The team will develop a test matrix that will evaluate the impact of the following variables: manufacturer, color, directional view, daylight conditions on the gradation of LED traffic signals. These results will be analyzed using the methodology developed as part of the previous study.
    Project Amount
    $ 49,022