This section gives a brief description of the keycharacteristics of the AZTDM model space provided by ADOT for this peer review.
Socioeconomics
Socioeconomic growth within the state of Arizona is the primary driver of travel demand. The population in Arizona is expected to nearly double in the next 40 years, from just over 6 million in 2010 to over 12 million in 2050. The future population follows the historical trend where each decade since 1970 has seen substantial growth.
Growth has been due primarily to natural birth and to immigration. Factors such as climate, geographic location and a strong job market have also fostered the growth. The climate factor has also attracted a significant seasonal senior population. This "snowbird" population travels to Arizona during the winter months then leaves in the spring. Despite the perception of a large senior population, Arizona has a young population with an average age below the national average.
Most of the state's population resides in the urban areas, a trend which is expected to continue in the future. Water rights have been secured to support the forecasted growth in the urban areas (rural areas have limited water rights to support growth). With growth occurring in the urbanized areas, it is expected that the metro areas will link up creating a "megapolitan" area containing approximately 85% of the state's population. Much of the transportation infrastructure for this megapolitan area has yet to be built.
Transportation Infrastructure
Arizona hosts five key interstate corridors which serve as the backbone transportation system for intrastate and interstate travel. I-40, I-8 and I-10 make up the primary east-west corridors. I-40 connects California and New Mexico through the north-central portion of the state and passes through Flagstaff. I-8 and I-10 pass through the southern part of the state connecting California to New Mexico through Yuma, Phoenix and Tucson. I-17 and I-19 form the primary north-south corridors in Arizona. I-17 begins at I-40 in Flagstaff passing through Phoenix and Tucson. I-19 completes the final north-south leg connecting Tucson with Mexico. The stretch of the I-10/I-17 corridor through Phoenix and Tucson is considered one of the most important portions of the interstate system in Arizona having and expecting to have the highest volumes in the state.
Transportation corridors in the northern part of the state are limited by geographic features, such as the Grand Canyon, national and state parks, and tribal lands.
ADOT manages the modeling program for the statewide model. The AZTDM is expected to have a role in the following transportation planning studies and projects:
ADOT's overall goal and motivation for seeking a TMIP peer review is to have the peer review panel members assist ADOT staff in identifying the best practices in statewide travel modeling to enhance the methods employed in the AZTDM and to improve its utility for planning analyses at state, regional, and municipal levels. To that end, the peer reviewers spent a day responding to specific questions from ADOT and its planning partners.
ADOT would like the TMIP peer review to particularly focus on the transition from a 3 step, highway-oriented travel demand model to a 4-step travel demand model that includes a mode choice component. Additionally, guidance was sought on supporting data collection activities and on methodologies for truck and freight modeling. ADOT prepared a list of specific topics for which they sought the panel's comments and recommendations. The list of topics is presented in section 4 and of this report. The panel's response on these topics is presented in section 5.
ADOT, along with its partner agencies, will critically assess the feedback from the peers when prioritizing its model development plan. While the advice of the peers is invaluable, there are many factors to work through when considering a model improvement strategy, and therefore the recommendations of the peers should be regarded as recommendations for ADOT and its partners.
