It uses a new paradigm of modeling individual travelers and their multi-modal transportation based on synthetic populations and their activities.
Compared to other transportation aggregate models, TRANSIMS represents time consistently and continuously, as well as detailed persons and households.
Networks can be exported from other traffic analysis tools into a fairly simple tabular format to be input into TRANSIMS.
However, many details that are not typically provided by common data sources are needed, such as traffic signals, turn lanes, etc.
In addition, small random variations are applied to survey records to avoid exact duplications for the many different synthetic households.
It highly depends on the availability of a recent and up-to-date activity survey, as well as detailed zoning information requiring manual adjustments.
This step is to read individual activities previously generated, then determine the fastest route at that time of the day.
The algorithm includes time-dependent optimization of the network based on link delays that vary during the day.
The microsimulator and the router work in an iterative loop to equilibrate the assigned traffic in the network.
The microsimulator follows those travel plans and determines a new set of link delays that are used to replace the ones previously used by the router.
The microsimulation can lead to highly detailed snapshot data, for example, the exact location of every traveler at any given time.
There has been much discussion in the transportation profession concerning how widely adopted TRANSIMS will be, producing several schools of thought.
This accelerated adoption of TRANSIMS might exceed the capability of project staff to support the affected regions.
A final school of thought is that in the beginning, TRANSIMS will indeed be used mainly by larger MPOs with particularly sophisticated transportation planning questions.
Subsequently, TRANSIMS would evolve into versions which would be more appropriate for MPOs with smaller staffs and different analysis needs.
[8] The Dallas case focused on development of a microsimulation in TRANSIMS which would be robust enough to execute the travel itinerary of each individual in an urban region.
To test these and other model sensitivities, the Portland staff assembled the actual local street and traffic signal plans to compare with the results of the synthesis.