Council hears technical briefing on North Thirtieth Street travel-time modeling, no call-up requested

City staff and consultants briefed Boulder City Council on the North Thirtieth Street preliminary design and the community environmental assessment’s travel-time projections, and council members asked technical questions but chose not to call the item up for formal action.

Consultants described methodology and limitations

Valerie Watson, interim director of Transportation & Mobility, introduced the project and invited the project team to answer technical questions. Chris Vogelsang, traffic engineer with OB Consulting, explained the team used a microsimulation program (TransModeler) to build a calibrated model of the corridor, run multiple stochastic simulations of proposed conditions and report average and maximum travel-time changes.

Vogelsang described the steps: collect existing traffic data, calibrate the model to reflect current conditions, then modify lanes, signal timing and other geometry to test alternative designs. He said the model runs multiple iterations and the team reported both average and maximum travel-time changes from the simulations. "We use a microsimulation, a traffic microsimulation program," he said, adding that results are statistical outputs from repeated runs.

Council questions

Councilmembers pressed consultants on two topics: whether the modeling has been truth-tested against post-construction performance elsewhere, and whether the model assumed traveler diversion (drivers taking alternate routes) when lanes are removed. Vogelsang said model developers have performed follow-up studies in some jurisdictions but project consultants have not performed extensive local truth-testing in Boulder; he also said the project model did not assume diversion in the travel-time projections shown to council.

Financing and grant status

Councilmember Mark asked whether project financing is secured. Staff said the project has federal grant funding identified but timing to move forward remains “undetermined at this time,” and staff clarified that receipt and timing of federal funds were not guaranteed.

Outcome

No councilmember moved to call the project up for formal action, and staff noted the hybrid alternative was a creative staff proposal worth further consideration. The item will remain on the call-up check-ins list but was not called to a formal hearing or vote at this meeting.