American Institute of Certified Planners (AICP) Practice Exam

Which of the following methods would determine trip distribution between traffic zones?

1. Gravity model

2. Cross tabulation model

3. Modal Split analysis

4. Parking space requirements

The correct answer is: Gravity model

The gravity model is a widely used method for determining trip distribution between traffic zones based on the principle that trips are attracted to destinations in proportion to their size (such as population or employment) and inversely related to the distance between the origin and destination. This model is analogous to the law of gravity in physics, which suggests that the amount of interaction between two locations decreases as the distance between them increases. In practical terms, the gravity model takes into account the characteristics of both the origin and destination zones, allowing planners to estimate the volume of trips based on various factors such as zone size and accessibility. This method is particularly effective in urban planning and transportation studies, as it provides a structured approach to predicting movements between different areas, aiding in traffic forecasting and infrastructure planning. Other methods listed, such as cross-tabulation model, modal split analysis, and parking space requirements, serve different purposes within transportation planning. They may analyze travel behavior or assess transportation system capacity but do not specifically focus on the direct distribution of trips between zones as the gravity model does.