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Council weighs sound-wall options for 96th Avenue; CDOT cost metrics shape staff recommendation
Summary
A consultant noise study for the planned 96th Avenue widening identified limited beneficiaries and high per-capita costs for sound walls. Staff recommended against building walls under CDOT/FHWA thresholds but council asked for targeted public outreach of beneficiaries and suggested a higher buy-in threshold.
Commerce City staff presented a noise-analysis follow-up for the 96th Avenue (E. 96th Avenue) widening project and asked council how to proceed on potential sound-wall mitigation.
The study, prepared for the city using CDOT and FHWA methodologies, modeled existing and future noise conditions for the widening project area and estimated who would “benefit” from noise mitigation. Staff cited CDOT’s metric in the analysis: “CDOT defines a beneficiary as someone who will receive at least 5 decibel reduction from noise mitigation efforts,” and said CDOT’s cost-effectiveness threshold is about $34,000 per benefited receptor.
The study considered walls on the western and eastern segments adjacent to the project and—excluding properties that face the roadway (front yards)—found relatively few benefited receptors. Staff presented cost estimates that exclude potential additional expenses such as utility relocations, private-fence relocation or land acquisition. For the western segment (excluding 43 front-facing homes) staff identified 12 beneficiaries and a construction-only cost estimate of about $635,000, or roughly $53,000 per beneficiary. For the eastern segment (excluding 34 front-facing homes) staff estimated 30 beneficiaries and about $1.1 million in construction cost, or about $39,000 per beneficiary. Staff showed that including front-facing yards would reduce per-beneficiary cost below the CDOT threshold.
Why it matters: CDOT and FHWA guidance typically inform sound-wall decisions; building walls that do not meet cost-effectiveness thresholds would be an atypical city-funded departure and would require council direction and public outreach.
Council discussion focused on resident acceptance, timing and cost. Council member Ford and others urged engaging beneficiaries before committing funding. Council member Kim and council members who spoke favored targeted outreach to the identified beneficiaries, and several asked staff to seek a higher participation threshold than CDOT’s 50% guideline before moving forward. Council members also discussed the practical and visual impacts of walls that would be 8—14 feet tall in places and the difficulty of retrofitting walls in front yards.
Staff recommended not moving forward under CDOT/FHWA thresholds because construction costs per beneficiary exceeded the standard guideline, but said council may direct staff to proceed outside those guidelines and asked which segments council would fund and whether staff should seek beneficiary approval. Several council members asked staff to expand outreach to the identified beneficiaries and to adjacent neighborhood groups and homeowners associations, and to time any mitigation discussion with the widening construction so decisions and installation (if approved) could be coordinated.
Ending: Council asked staff to proceed with targeted public outreach to benefited receptors (and to coordinate broader neighborhood briefings) and to return with results; multiple members indicated they preferred more-than-50% beneficiary support before the city would fund sound walls in front yards.
