@article{ref1,
title="Measuring Critical Gap",
journal="Transportation science",
year="1983",
author="Hewitt, RH",
volume="17",
number="1",
pages="87-109",
abstract="[Abstract unavailable]  <p>Language: en</p>",
language="en",
issn="0041-1655",
doi="",
url="http://dx.doi.org/"
}