American Institute of Certified Planners (AICP) Practice Exam

What is the most common measure of traffic volume used in planning?

1. VMT

2. LOS

3. AADT

4. Peak Hourly Volume

The correct answer is: LOS

The most common measure of traffic volume used in planning is the Average Annual Daily Traffic (AADT). This metric represents the average number of vehicles that pass a point on a roadway each day over the course of a year. AADT is particularly useful because it accounts for seasonal variations and provides a standardized way to compare traffic volumes on different roadways. This makes it an essential tool for transportation planners in assessing roadway capacity, determining funding needs, and projecting future traffic growth. While other metrics like Vehicle Miles Traveled (VMT) and Level of Service (LOS) are important in transportation studies, they serve different purposes. VMT gives a broader picture of travel behavior over time but isn’t as focused on traffic volume at specific points. LOS assesses the quality of service of a roadway or intersection but does not quantify traffic volume in the same way AADT does. Peak hourly volume measures traffic at specific times during the day but does not represent an average or provide a comprehensive view of daily traffic patterns. In summary, AADT stands out for its ability to provide a consistent and annualized measure of traffic volumes, making it a cornerstone in traffic planning and analysis.