4.4.1 General

Analysis results are the most reliable when typical geometric configurations are analyzed. All analysis tools have some limitations. Below are some examples of the limitations of deterministic tools:
  • Network affect caused by congestion;
  • Traffic flows will not adjust travel routes due to congestion;
  • Interference caused by roadside parking;
  • HOV, High-Occupancy Toll (HOT), or other managed lanes;
  • Tight diamond interchanges;
  • Impacts of multiple closely spaced driveways along a street segment;
  • Interactions between bicycles, pedestrians, and vehicles sharing the same roadway;
  • Impacts of on-street parking, commercial vehicle loading, and double parking;
  • Impacts of changes in roadway environment (or other violations of driver expectation);
  • Impacts of tolling on travel patterns;
  • Driver behavior;
  • Two-way left-turn lanes; and
  • v/c does not capture spatial congestion
The following are some examples of the limitations of stochastic tools:
  • Models may have difficulty capturing the effects of a continuous two-way left-turn lane;
  • It is recommended to run models multiple times to capture randomness or average travel experience; and 4-11 2024 | Traffic and Safety Analysis Procedures Manual
  • Impacts of driver behavior (obstruction of visibility, roadway distractions, etc.)