Which model outlines the traditional approach to transportation planning?

The four-step model is a foundational framework in transportation planning that outlines the traditional approach to understanding and predicting travel behavior. This model consists of four distinct stages: trip generation, trip distribution, mode split, and trip assignment.

1. Trip Generation: This first stage involves estimating the number of trips originating from or destined to specific areas. It analyzes factors such as demographics, land use, and development patterns to predict how many trips will be made.

2. Trip Distribution: After generating the estimated number of trips, this stage allocates the trips from the origin zones to destination zones, essentially determining where trips will go.

3. Mode Split: In this phase, the model predicts what mode of transportation travelers will choose (e.g., car, bus, train) based on factors like cost, travel time, and convenience.

4. Trip Assignment: The final stage assigns the predicted trips to specific routes on the transportation network, allowing planners to understand how traffic will flow and what impacts it may have on existing infrastructure.

These stages collectively provide a structured way for planners to analyze and predict travel patterns and inform transportation infrastructure development. This model has been a cornerstone of transportation planning methodologies for decades, serving as a reliable approach for both