4.2.1 Operating Speed

Operating speed is the speed at which drivers are observed operating their vehicles during free-flow conditions.
The 85
th
 percentile of the distribution of observed speeds is the most frequently used measure of the operating speed
 associated with a particular location or geometric feature.
The following geometric design and traffic demand features may have direct impacts on operating speed:
  • Horizontal curve radius;
  • Grade;
  • Access density;
  • Median treatments;
  • On-street parking;
  • Signal density;
  • Vehicular traffic volume;
  • Lane widths;
  • Sight distance; and
  • Pedestrian and bicycle activity.