Senate Transportation hears SLR report on excessive vehicle noise, reviews options for S.66

At a Senate Transportation Committee meeting, lawmakers heard an overview of a report prepared for the Agency of Transportation that evaluated ways to address excessive motor-vehicle noise and considered implementation implications for bill S.66.

The report, prepared by SLR Consulting, was produced under Act 41 (2023) and examined whether a statutory or inspection-manual noise standard should be adopted, the cost to add noise testing to the Vermont Periodic Inspection Manual (VPIM), training costs for law enforcement, non-testing enforcement options and approaches used in other states.

SLR Consulting’s U.S. acoustics manager, David Jones, told the committee the study did not endorse a single path but rather laid out benefits and challenges for five broad options: strengthened visual inspection language in the VPIM, sound-level testing in inspection stations, law-enforcement roadside sound testing, a testing-as-a-defense approach (used in Maine), and fixed-location automated “drive-by” systems including acoustic-camera technology. “The report includes no specific recommendation about whether there should be a noise standard,” Jones said, adding the study’s role was to present trade-offs.

Jones described key stakeholder concerns revealed during interviews with the Vermont League of Cities and Towns, Vermont Sheriffs Association, Vermont Association of Police Chiefs, Vermont State Police and the Vermont Department of Motor Vehicles. He said stakeholders cited three recurring issues: enforceability and repeatability of measurements, the potential reallocation of law-enforcement resources, and the subjective wording of some existing local ordinances. “It can be difficult and complicated,” Jones said of measurement and enforcement.

On technical approaches, Jones said in-shop sound testing could use a Type 2 sound-level meter (roughly $500 each), a defined measurement distance and a specified engine RPM, but would add time to inspections and require purchase, calibration and recurring maintenance of instruments. He estimated a low-cost change to the VPIM (rule and software edits) at roughly $30,000 one-time; a statewide program that supplied meters to every inspection station drove an illustrative one-time cost in the mid-six-figure range and recurring calibration/maintenance costs on the order of $100,000 per year. For law-enforcement testing, Jones said detection in busy roadside environments can be difficult because a single meter records combined ambient sound rather than isolating a single vehicle.

Jones highlighted emerging acoustic-camera systems — microphone arrays combined with video and license-plate readers — that can spatially locate sound sources on a vehicle in motion. “I think it’s gonna be kind of a game changer in terms of vehicle noise enforcement,” Jones said, while cautioning the technology carries higher per-site costs and may require statutory changes to permit unattended or remote enforcement similar to speed-camera frameworks.

City councilor Lori Smith of South Burlington testified in support of regulation requiring mufflers that avoid disruptive sounds. “This bill is important to our city because regulation of these noises…are something we have very little ability to regulate, control, or enforce,” Smith said, adding that late-night motorcycle rallies and engine revving are recurring problems and that by the time police arrive the vehicles are gone.

Wade Cochran, director of enforcement and safety at the Agency of Transportation, told the committee AOT “100% stand[s] behind the noise study and the findings with the bill,” but urged attention to cost implications for small inspection shops and for law enforcement. Cochran and other AOT staff asked the committee for clearer guidance on what equipment would be mandated and requested time to supply more detailed cost breakdowns and shop-level impacts.

Committee members pressed staff on commercial-truck enforcement and distinctions between heavy-truck inspection stations and passenger-vehicle stations. Lieutenant Daniel Merchant, DMV Enforcement Safety Investigations Division, explained heavy-truck inspections typically occur at designated fleet stations that meet different physical and equipment requirements than public passenger-vehicle sites. “So it would, we could, if we chose to in here, treat inspection for big trucks separately from the pleasure cars. Absolutely,” Merchant said.

Senate committee members asked several practical questions: whether muffler modifications can be visually detected during inspections, how inspection software (the Automated Vehicle Inspection Program) would be modified, and whether training would be needed for a subset of officers rather than all patrol officers. Jones said some modifications — straight pipes or the complete absence of a muffler — are visually obvious, while internal muffler changes can be difficult to detect without under‑carriage access. He said moving tests typically used a measurement at 50 feet from the vehicle centerline in many states’ standards, while static in-shop testing typically measures at set distances (for example, ~2 feet from an exhaust port under controlled RPM) and that states differ on exact test distances and decibel limits.

No committee votes were recorded in this session. Committee members asked AOT and DMV staff to return with further details: clearer cost estimates by station type, equipment specifications and options to treat heavy-truck inspections separately from passenger-vehicle inspections. The committee also flagged statutory and legal considerations for automated enforcement methods and the potential need to amend existing Vermont law to allow unattended remote enforcement.

The discussion made clear the trade-offs for any policy choice: objectivity and in‑field coverage of moving-vehicle tests versus practical constraints around meter accuracy, ambient noise, officer workload, shop capabilities and upfront costs. The committee left the hearing by scheduling follow-up information from AOT and the DMV on equipment standards, cost burdens for small shops and the inspection-manual language needed to implement any change.