1371716 - Estimating a Demographic Profile for the Central Puget Sound Region Freeway Network

Freeways play a critical role in the transportation network. They also present several equity concerns for the users and communities they serve. Thus, it is critical to have a concrete understanding of the populations that use freeways. Currently there is no methodology to determine this demographic profile, nor are there readily available datasets that capture this information empirically. This presentation shows a methodology utilizing ecological regression to estimate the demographic profile of freeways. Ecological regression, also called ecological inference, allows for the extraction of individual level characteristics from aggregate data sources. In this case these are freeway usage, census, and origin destination data respectively. This provides a more thorough understanding of the demographic profile of a freeway network. For this presentation, the Central Puget Sound region is used to verify this methodology. The demographic profile of incomes for freeway users is calculated and compared to the demographic profile of incomes for the region. It was found that the income profile of freeway users is 0.5066% dissimilar to that of the entire population, indicating that freeway usage is essentially representative when assessing user income. This result is meaningful as it shows the effectiveness of this methodology for evaluating the demographics of critical transportation networks which can further the study of transportation equity which relies on understanding these critical demographics.