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TRANSIMS
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TRANSIMS FUNDAMENTALS

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ADDITIONAL TRANSIMS INFORMATION

TRANSIMS

Activity Generator

TRANSIMS generates a list of activities for each individual in a synthetic household by using the Activity Generator module. These activities are based on demographic surveys and activity surveys collected from real households in the study area. The demographic survey contains information about characteristics of each individual household in the survey sample of real households used to match the demographics characteristic of the synthetic households obtained from the census PUMS data. The activity survey obtained from the sample of real households includes travel and event-participation information for each individual household member over a period of one or more days. The household activity survey, the synthetic household obtained from the Population Synthesizer module and the network data constitute the input list to the Activity Generator.

Input/Output data flow for Activity Generator: Inputs are the household activity survey (representative sample of population including travel and activity participation of all household members, recorded continuously for 24+ hours), the synthetic household obtained from the Population Synthesizer module and the network data (nodes, links and activity locations including land use and employment).
Input/Output data flow for Activity Generator

The assignment of activities from survey households to synthesized households is done based on household demographic characteristics. The demographics of synthetic households must match the demographics of the survey households. A classification and regression tree algorithm (CART) is used to group the survey households having similar activity time patterns according to these demographic characteristics.

Example CART tree using Household Demographics: households are categorized by number of workers, then number of members, then age, income and density.
Example CART tree using Household Demographics

The end nodes in this tree represent survey households that have similar activity patterns based on the classified demographic characteristics. The matching is done by selecting a survey household in the end node and giving its 24-hour activities to a synthetic household that has the same demographic path to that end node.

The activity matching is done for each individual member of the synthetic household based on age, gender, and relation. Each activity assigned to each individual has as associated activity type (i.e. work, shopping, school, etc), duration, mode preference, beginning time, and ending time. The figure below shows an example of the activity list for an individual synthetic household.

Example of activity list of a synthetic household in TRANSIMS: This household consists of 3 people. The first member, person ID 55728, travels from home to work by car and then goes back home. The second member, person ID 55729, and the third member, person ID 55730, leave home to visit by walking and then come back home. Next all the members in this household go to other, shop and return home. The first member drives the car the other two are passengers.
Example of activity list of a synthetic household in TRANSIMS

All activities in TRANSIMS separated by time and location require travel between them. Therefore, a travel mode to each activity is assigned. However, the Route Planner searches for the best of all possible modes to execute the travel between two activities. To locate the non-home activities, TRANSIMS use a model that considers the zonal attractiveness value, the travel times between activities and the intensity of activities within the zone.