E 553 Factors Affecting Intersection Capacity

The following factors indicate the data needed to analyze the capacity of a given Intersection or to determine its required geometry for a given traffic volume:

1. Basic Physical and Operating Conditions:
   1. One-way or two-way operation.
   2. Parking conditions.
   3. Width of approach.
2. Environmental Conditions:
   1. Metropolitan area population.
   2. Location within the metropolitan area.
   3. Peak-hour factor.
   4. load factor.
3. Traffic Characteristics:
   1. Traffic volume to be served on each approach.
   2. Turning movements.
   3. Trucks and buses.
   4. Local buses (bus stops).
4. Control Measures:
5. Traffic signals — functional type and phasing.
6. Degree of channelization and approach lane markings.

Because so many factors influence interrupted flow through intersections, these flow criteria are developed around typical or average conditions. Adjustments either upward or downward, as indicated in Section E 554, Signalized Intersection Capacity Data may be applied to fit the specific conditions at hand.