@article{ref1,
title="Traffic Signal Maintenance Requirements",
journal="Journal of transportation engineering",
year="1983",
author="Kraft, WH and Doughty, JR",
volume="109",
number="3",
pages="471-480",
abstract="<p>[Abstract unavailable]</p>",
language="",
issn="0733-947X",
doi="",
url="http://dx.doi.org/"
}