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8. Trip Distribution

Trip distribution involves the process of allocating generated trips to various destinations based on the choice of travel purpose. This chapter discusses essential methods for trip distribution, including the growth factor model and gravity model, highlighting their calibration and application in transportation planning.

Sections

Trip Distribution

Trip distribution is the process of allocating generated trips from various origins to different destinations based on established models, crucial for transportation planning.

8 Section Overview

Start current section content and materials

8.1 Overview

This section introduces trip distribution, the process of allocating generated trips from one zone to multiple destination zones, highlighting models used for this purpose.

8.2 Definitions and notations

This section defines essential terms and notations used in the trip distribution process of transportation engineering.

8.2.1 Trip matrix

The trip matrix is a two-dimensional representation of travel patterns across zones in a study area, detailing trips between origins and destinations.

8.2.2 Generalized cost

This section discusses the concept of generalized cost in trip distribution models, which encompasses all disutility factors such as travel time, costs, and convenience.

8.3 Growth Factor Methods

This section discusses growth factor methods used in trip distribution, focusing on uniform and doubly constrained growth factor models.

8.3.1 Uniform growth factor

The uniform growth factor model applies a single growth rate across all zones to estimate trip distribution when only general growth data is available.

8.3.2 Example

This section presents an example of applying the growth factor model to calculate the expanded origin-constrained trip table based on given trip data.

8.3.3 Doubly constrained growth factor model

The doubly constrained growth factor model utilizes two sets of growth factors for zones to ensure that trip productions and attractions are balanced.

8.3.4 Advantages and limitations of growth factor model

This section discusses the advantages and limitations of the growth factor model used in trip distribution modeling.

8.4 Gravity model

The gravity model is a method for distributing trips between origins and destinations based on their characteristics and the distance between them, analogous to Newton’s law of gravitation.

8.5 Summary

This section summarizes key concepts related to trip distribution methods in transportation planning.

8.6 Problems

This section presents problems to apply concepts of trip distribution using various models.

Learning Objectives

  • Trip generation is the process of determining travel needs within zones.

  • Trip distribution is the second stage of travel demand modeling, allocating trips to various destinations.

  • Two key methods for trip distribution are the growth factor model and the gravity model, each with its own advantages and limitations.

Key Concepts

Trip Matrix

A representation of the trip pattern in a study area using a matrix where rows and columns represent zones, with values indicating trips between origins and destinations.

Generalized Cost

A cost measure incorporating multiple factors like travel time, fare, and convenience, affecting trip distribution between two zones.

Growth Factor Model

A method that utilizes growth rates from observed trip data to project future trip distributions based on short-term trends.

Gravity Model

A model based on the analogy of gravitational force, predicting trip distribution by considering the size of areas and the distance between them.

Doubly Constrained Model

A model taking into account both trip productions and attractions, ensuring balanced outputs for trip distribution across various zones.

Practice Exercises

Total Questions

2

Estimated Time

4 min

Passing Score

70%

Instructions

  • Read each question carefully
  • You can use hints if you need help
  • Complete all questions before submitting
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