Ambag

To support the metropolitan transportation planning activities and decision making process AMBAG staff develops, maintains and applies a Regional Travel Demand Model (RTDM). The AMBAG RTDM has been peer reviewed and meets best practice standards. A Federal Highway Administration (FHWA) sponsored TMIP peer review was conducted in 2013 to review the newly updated AMBAG model and discuss future model needs and improvements. The Metropolitan Transportation Plan (MTP) determines what transportation projects are programmed into the RTDM. The current RTDM reflects transportation projects adopted by the AMBAG Board of Directors in June of 2018.

AMBAG by federal mandate is required to maintain two major planning documents: the Metropolitan Transportation Plan (MTP) and the Metropolitan Transportation Improvement Plan (MTIP). These two plans and other AMBAG transportation studies rely heavily on the Travel Demand Model for predicting the impact of travel growth and evaluating potential transportation improvements. The Travel Demand Model comprises a large number of data files in order to represent the many facets of the transportation environment. These data sets provide assumptions on population, employment, income, roadway and transit networks and transportation costs. Using this data the model estimates:

  • Traffic congestion
  • Freight traffic
  • Passengers riding existing and future transit services
  • Greenhouse Gas (GHGs) emissions analysis by automobile

Contact Bhupendra Patel, Director of Modeling, at bpatel@ambag.org if you have questions regarding AMBAG's Regional Travel Demand Modeling activities.

2018 Regional Travel Demand Model
The 2018 RTDM is a technical update only to the 2014 RTDM. The technical update to the 2018 RTDM uses a new base year of 2015 to incorporate land use and transportation network changes. The 2015 base year was not re-estimated, re-calibrated, or re-validated. The 2014 RTDM was an entirely new travel demand model estimated and calibrated to 2010 conditions using data from the 2010-11 California Household Travel Survey (CHTS), Census, employment, and traffic counts data. The model utilizes advance techniques to capture travel behavior at a more individual-level and incorporates disaggregate level data into some of the modeling stages. The primary reasons for introducing more disaggregate level data into the model was to assist in addressing elements of SB 375, and to pave the way for a possible transition to a tour-based modeling approach in the future. This updated model is a traditional four-step trip-based approach, and as such includes models for Trip Generation, Trip Distribution, Mode Choice, and Trip Assignment. Specific differences compared with traditional approaches include a population synthesis to drive the trip generation socioeconomic variables, calculation of the 4D variables (Density, Diversity, Design, and Destinations) using GIS techniques to support inputs to various model stages, the use of person-based trip rates, destination choice model for the trip distribution, and a mode choice component designed and estimated entirely from the survey.

The new model represents a significant improvement in functionality to the previous AMBAG RTDM. The updated AMBAG RTDM has implemented most of the short-term and medium-term model improvement recommendations from the 2011 Travel Model Improvement Program (TMIP) peer review. A peer review of the updated RTDM took place in August of 2013. The model was used to develop AMBAG’s 2040 Metropolitan Transportation Plan (MTP) and Sustainable Communities Strategy (SCS). For more information, please review the AMBAG 2018 RTDM technical documentation

Modeling Programs