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TPO kicks off scoping for major travel demand model update; workshop scheduled to refine technical options
Summary
TPO staff and consultant Caliper led a scoping discussion for a major update to the 10‑county regional travel demand model, citing the need to reflect post‑COVID travel behavior and to incorporate new data sources (household survey, big truck GPS data). A stakeholder workshop was announced to refine architecture and budget.
The Knoxville Regional TPO Technical Committee heard an overview of scoping work for a major update to the regional travel demand forecasting model and was invited to a stakeholder workshop scheduled to start at 10:30.
Mike Conger, TPO staff, said the existing regional model covers a 10‑county area and had its last major household survey in 2008; staff validated a 2022 base year but noted the model platform and survey data are aging. The TPO has been conducting a pooled household survey project (My Travels Count) across MPOs with a target of 3,000 samples for the 10‑county area; Conger said roughly 1,000 samples have been collected to date and staff expect to continue collection into the fall.
Vince Bernard of Caliper Corporation summarized survey responses from internal stakeholders and described priorities and tradeoffs identified in early engagement. Stakeholders rated technical analysis as very important and prioritized subarea studies, transit analyses and bicycle/pedestrian planning as likely uses for the updated model. Respondents also identified traffic‑impact analysis for developments and land‑use scenario testing as high‑value applications. Technical options discussed included the current hybrid model architecture versus a full activity‑based model (ABM); conventionally, ABMs can offer greater behavioral detail but carry substantially longer run times and higher costs.
Committee members pressed staff and the consultant on freight and truck modeling. Vince Bernard said heavy truck modeling can be improved using modern big data sources and counts; modeling delivery‑style light/medium commercial tours requires additional data and methods. TDOT staff and local members noted current uses of big truck data (for example in corridor studies on I‑40/I‑75) and discussed pairing big data and model results to analyze diversion and bypass effects.
Conger and consultant staff emphasized the workshop will examine design choices (architecture, spatial and temporal resolution, representation of bike/ped, truck tours and operational elements such as turning lanes and signals) and produce a final scoping memo with cost ballparks to inform a future RFP. The TPO expects to issue a model RFP after household survey collection completes and the final scope is refined.
"There is a trade off between how detailed you can get down...and the model runtime," Bernard said. "Activity‑based models can provide answers hybrid models can't, but they do come at a significant cost in terms of runtime and computation."
