Models & The Questions We Ask

Cite as: Wasserman, D.; Croshere C.; Martens K., (2022). Models and the Questions We Ask. State of Transportation Planning 2022. American Planning Association Transportation Division. Retrieved from https://issuu.com/apatransport/docs/2022_sotp

View at: State of Transportation Planning 2022

Abstract

Travel Demand Modeling (TDM) has defined the thought processes, practice, and procedures of transportation professionals for close to seventy years. With origins tied to the construction of the interstate highway system, our pursuit to understand the connections between human behavior and infrastructure is an under-examined part of transportation planning’s history. Many of the underlying assumptions in modeling practice influence transportation legislation, development review procedures, impact fee schedules, parking regulations, and environmental impact statements. However, as transportation investments are expected to address new goals such as economic development, environmental justice, improving public health, or mitigating/adapting to climate change, travel demand modeling practice needs to evolve. Our focus on travel demand as a technical exercise carries implicit assumptions and values that should be scrutinized if we wish to avoid reinforcing the disparities of the past. With new challenges, we need new questions centered around who benefits from investments, the role of transport in increasing access to opportunity, transport costs and location affordability, and how the systems and processes of planning can change to meet more multifaceted goals.

Traffic flow by desirable routes to major industries and central business district (printed in McLachlan & Lynch, 1950, p.365). Image scan by Cheryl Croshere whose academic work included researching the origins of travel demand models.