Difference between revisions of "Four-step travel model"
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| + | ==Introduction== | ||
The four-step travel model is a ubiquitous framework for determining transportation forecasts that goes back to the 1950. | The four-step travel model is a ubiquitous framework for determining transportation forecasts that goes back to the 1950. | ||
| + | ==The Four Steps== | ||
The four steps are described as follows:<ref>Wikipedia: Four-step models https://en.wikipedia.org/wiki/Transportation_forecasting#Four-step_models</ref> | The four steps are described as follows:<ref>Wikipedia: Four-step models https://en.wikipedia.org/wiki/Transportation_forecasting#Four-step_models</ref> | ||
| − | + | ===Trip Generation=== | |
| − | + | Trip generation determines the frequency of origins or destinations of trips in each zone by trip purpose, as a function of land uses and household demographics, and other socio-economic factors. | |
| − | + | ===Trip Distribution=== | |
| − | + | Trip distribution matches origins with destinations, often using a gravity model function, equivalent to an entropy maximizing model. Older models include the fratar model. | |
| + | ===Mode Choice=== | ||
| + | Mode choice computes the proportion of trips between each origin and destination that use a particular transportation mode. (This modal model may be of the logit form, developed by Nobel Prize winner Daniel McFadden.) | ||
| + | ===Route Assignment=== | ||
| + | Route assignment allocates trips between an origin and destination by a particular mode to a route. Often (for highway route assignment) Wardrop's principle of user equilibrium is applied (equivalent to a Nash equilibrium), wherein each driver (or group) chooses the shortest (travel time) path, subject to every other driver doing the same. The difficulty is that travel times are a function of demand, while demand is a function of travel time, the so-called bi-level problem. Another approach is to use the Stackelberg competition model, where users ("followers") respond to the actions of a "leader", in this case for example a traffic manager. This leader anticipates on the response of the followers. | ||
==References== | ==References== | ||
Revision as of 21:27, 4 December 2019
Introduction
The four-step travel model is a ubiquitous framework for determining transportation forecasts that goes back to the 1950.
The Four Steps
The four steps are described as follows:[1]
Trip Generation
Trip generation determines the frequency of origins or destinations of trips in each zone by trip purpose, as a function of land uses and household demographics, and other socio-economic factors.
Trip Distribution
Trip distribution matches origins with destinations, often using a gravity model function, equivalent to an entropy maximizing model. Older models include the fratar model.
Mode Choice
Mode choice computes the proportion of trips between each origin and destination that use a particular transportation mode. (This modal model may be of the logit form, developed by Nobel Prize winner Daniel McFadden.)
Route Assignment
Route assignment allocates trips between an origin and destination by a particular mode to a route. Often (for highway route assignment) Wardrop's principle of user equilibrium is applied (equivalent to a Nash equilibrium), wherein each driver (or group) chooses the shortest (travel time) path, subject to every other driver doing the same. The difficulty is that travel times are a function of demand, while demand is a function of travel time, the so-called bi-level problem. Another approach is to use the Stackelberg competition model, where users ("followers") respond to the actions of a "leader", in this case for example a traffic manager. This leader anticipates on the response of the followers.
References
- ↑ Wikipedia: Four-step models https://en.wikipedia.org/wiki/Transportation_forecasting#Four-step_models