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Additional Physical Format: | Online version: Zwahlen, Helmut T. Evaluation of CTCLS series traffic signal load switches in the field. Athens, Ohio : Human Factors and Ergonomics Laboratory, Ohio Research Institute for Transportation and the Environment, Russ College of Engineering and Technology, Ohio University ; Springfield, Va. : Available through the National Technical Information Service, [2003] (OCoLC)1100823416 |
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Material Type: | Government publication, State or province government publication, Internet resource |
Document Type: | Book, Internet Resource |
All Authors / Contributors: |
Helmut T Zwahlen; Andrew Russ; Sahika Vatan; Ohio Research Institute for Transportation and the Environment. Human Factors and Ergonomics Laboratory.; United States. Federal Highway Administration.; Ohio. Department of Transportation. |
OCLC Number: | 53158782 |
Notes: | "July 2003." |
Description: | ix, 126 leaves : illustrations ; 28 cm |
Responsibility: | prepared by Helmut T. Zwahlen, Andrew Russ, and Sahika Vatan. |
Abstract:
The purpose of this study was to evaluate the extended traffic signal light bulb longevity claims made by CLS for their CTCLS series load switches by testing in the field against conventional load switches in five different states (except Minnesota). In each state approximately 144 signalized intersections containing 512 load switches and 3456 bulbs were installed for the study, half using CTCLS load switches and half conventional load switches. The states involved were Ohio, Mississippi (the state and the city of Jackson), Michigan, Wisconsin, Minnesota (where no load switches or bulbs were installed), and Iowa (City of Waterloo). Four different major brands of bulbs were evaluated in the study (GE-Real, GE-Phillips, Sylvania, and Duro-test, with each brand assigned to a particular state (two states used Sylvania bulbs). Intersections used in the study were to be monitored and maintained for two years, and failed bulbs and load switches were tagged and returned to the study subcontractor, The Operator Performance Laboratory at the University of Iowa, for cataloging and analysis periodically during that time. The CLS claim that their CTCLS series load switches extended bulb life and reduced maintenance costs could not be investigated since ODOT decided to remove the CTCLS load switches due to safety and liability concerns after several of the switches gave dual indications or other malfunctions. The study was then modified to study all the bulbs using only conventional load switches (3456 bulbs per state). In addition, the Duro-test company went bankrupt after the test started. Overall, the bulb life portion of the study produced little useful data. In all cases, the states and cities tagged and returned at most a fraction of the failed bulbs. It appears that the extra work caused by the study may have been asking too much of already busy maintenance personnel. Thus it seems that studies that rely on extra efforts by state personnel over a long period of time are at best difficult to carry out. The two bulb brands (GE-Real (Ohio) and Sylvania (Jackson MS)) for which reasonably complete data were made available from internal department records would be unsuitable for use in Ohio, both exceeding the ODOT 2% failure criterion for the first year. A group relamping spreadsheet was created and evaluated, using Ohio District 4 as a test case for a limited sensitivity analysis. A relatively easy to use Excel spreadsheet was devised to compute the costs of group relamping as a function of relamping interval. The model shows a shallow minimum region at about 10 months, providing a minimized annual cost of
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