Design and Physical Factors of the Roadway

The design and physical factors of the roadway place a definite limitation on the safe operating speed of vehicles. These factors include:
  • horizontal and vertical curves
  • hidden driveways and other roadside developments
  • high driveway density
  • rural residential or developed areas
  • lack of striped, improved shoulders.
Chapter 5, Section 2,
Curves and Turns
, and Chapter 5, Section 5,
Descending Grades of Six Percent or Greater
of this manual provides the methods that must be used to determine if a curve or an obstruction to sight distance requires an advisory speed restriction.
The effects of such factors as lane width, condition of surface, type and width of shoulders, frequency of intersections, and roadside development are not so easily measured. As a general rule, especially on tangents, these factors will be measured on the basis of prevailing speeds as determined by speed checks.