The CMAP Travel Demand Models are a set of computational tools used to predict transportation system use under a variety of socioeconomic conditions and public policy scenarios.
CMAP's Trip-Based Models
CMAP's current "trip-based" models are used to evaluate long-range regional planning strategies and estimate transportation contributions to regional air quality. The results of these models also help transportation engineers design their projects for construction. Our "trip-based" method is widely accepted and is the primary approach used for metropolitan transportation planning nationwide.
The "trip-based" models are documented in support of CMAP's ON TO 2050 Comprehensive Regional Plan and required demonstration of Air Quality Conformity. The ON TO 2050 Travel Model Documentation Report describes the overall structure and flow of the CMAP trip-based models. The 2017 Travel Model Validation Report examines the reasonableness of CMAP's "trip-based" model results.
Modeling data -- both inputs and outputs -- are available on the CMAP Data Hub. Current trip-based data can be found under the group Current Regional Model Data. Older data is also archived there under the group Archived Regional Model Data. CMAP’s trip-based model code is maintained in a GitHub repository.
CMAP's Activity Based Models
CMAP has also developed an "activity-based" model (ABM), which is increasingly viewed as a superior method to trip-based models for understanding the socioeconomic determinants of travel choice and evaluating modern transportation solutions. These models are founded on the idea that people’s travel behavior is a result of their daily activities, i.e., the things people need to accomplish dictate where, when, how, and with whom they travel. ABMs seek to represent the choices made by individual travelers. To do this, the models must generate a schedule of daily activities for members of every household in the region, and then transform that information into sequences of trips that occur throughout the day.
The detailed information about people, households, and trips required by an ABM allow for a finer level of analysis than can be accomplished using a trip-based model. This also makes them better tools to analyze the effects of policy decisions such as implementing managed lanes, congestion pricing, or alternative transit fare structures. Development of the ABM was originally outlined in the Strategic Plan for Advanced Modeling at CMAP.
CMAP's ABM platform is CT-RAMP (Coordinated Travel and Regional Activity-Based Modeling Platform), which was developed open source by a consultant under contract to CMAP. Development of CMAP's ABM has occurred in three distinct phases:
1. The initial phase focused on the development of an ABM that would demonstrate sensitivity to highway pricing scenarios based on each traveler's individual value of time. Completion of this work provided CMAP with capabilities to evaluate toll and managed lane scenarios from the perspective of the user. The software delivered provided a complete methodological approach to activity-based modeling with all of the primary functions in place and a flexible system to allow for future analysis extensions to the ABM framework. This work was completed in June 2011 and is documented in the Phase 1 Final Report and User Guide.
2. The second phase of ABM development focused on improving model sensitivity to a wider range of non-traditional transit attributes, i.e., attributes that do not typically inform transit Level-of-Service calculations. This "transit modernization" component of ABM development concentrated on incorporating how people respond to changes in transit amenities, such as service reliability, personal safety, station and vehicle cleanliness, and crowding. This phase of ABM development was completed in June 2013 and is documented in the Phase 2 Final Report and User Guide.
3. Subsequent work on the ABM focused on the calibration of its sub-models and the overall validation of the model results. These activities were carried out by CMAP staff and their consultants. The results of these efforts are documented in the CMAP ABM Validation Report.
CMAP’s activity-based model code is maintained in a GitHub repository.
Other regional planning agencies nationwide have embarked on advanced model development programs, and CMAP joins them in a commitment to improve the state-of-the-practice in travel modeling. To inquire about our advanced travel model work program, please contact us at firstname.lastname@example.org.
CMAP's Freight Models
CMAP also hosts the monthly Chicago Area Travel Model User Group (CATMUG). If you are interested in learning more about research, development and applications in travel demand modeling, please join us. All are welcome.