perform major work on an existing facility, the next step is to establish the design
controls. The various factors considered for design controls may be generally
grouped into five categories: functional classification, traffic data, terrain, locale, and
design speed.
Functional classification is a way of grouping roadways together by the character
of service they provide. The initial division is between urban and rural roadways. The
urban classification may be defined differently in various parts of the country, but one
definition is incorporated areas having a population of 5000 or more (Ref. 1). Rural
areas are those areas outside of urban areas.