Several people emailed Traffic Lab recently with complaints about excessively noisy cars, trucks and motorcycles. This week’s Q&A dives into that issue, along with Seattle’s rule for parking near crosswalks.

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In response to last week’s question about darkly tinted car windows, some readers said their beef with motorists is over a different kind of equipment violation: loud exhaust systems.

Following our column that laid out the state law restricting how darkly tinted car windows can be, several people emailed Traffic Lab with complaints about passenger cars, trucks and motorcycles making excessive noise.

So this week we’ll explore the law governing mufflers and exhaust noise. We’ll also tackle a Seattle reader’s question about parking near crosswalks.

Here we go.

Q: Why are so many diesel passenger trucks allowed to heavily modify their exhaust systems so that they make as much noise and black smoke as possible? Some of these rigs are deafening and belch out black clouds. Isn’t there some kind of vehicle noise ordinance in counties or cities?

— Kelly Curtis, Olympia

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A: Under Washington law, motorists aren’t allowed to change their exhaust systems to make their engines louder, and all motorcycles, trucks and cars must have mufflers “in good working order” without noise-altering devices on highways.

But not all follow the rules.

Just a cursory Google search, “How can I make my exhaust system louder,” will uncover YouTube videos, Reddit threads and chat rooms with directions for making mechanical switches for cheap. One video even has an “illegal” warning label.

Keep in mind, loud exhaust noise can be a result of holes in the system or other equipment problems, not necessarily an intentional change.

No matter the case, though, the law specifies volume levels exhaust can’t exceed on highways: 95 decibels, measured 20 inches away, for most automobiles and light trucks, and 99 decibels for motorcycles. That’s about the same sound level you’d hear standing near a power mower.

“Average/normal exhaust is quiet and can’t be heard from blocks away,” Sgt. James Prouty of the Washington State Patrol wrote in an email. “Exhaust that produces excessive or unusual noise (whether modified or defective)” violates the law.

As for smoke, the law also regulates emissions from the exhaust pipe. The measure for those emissions is what’s called the Ringelmann chart, a scale that rates smoke density.

For all modern vehicles, emissions should obscure no more than 20 percent of vision, according to the law, meaning the smoke is barely visible.

And you’re right — local municipalities have codes that regulate exhaust systems. Sometimes those codes are modeled verbatim on state law, which is the case for the city of Seattle.

For Olympia’s rules, Kelly Curtis, you can check the city’s website.

Vehicle noise is one of many roadway regulations under the jurisdiction of law-enforcement officers from both local and state agencies.

But the number of loud trucks you’re seeing is likely a symptom of the same issue as with other unlawful vehicle modifications, such as over-tinted windows: Violators far outnumber enforcers, and law-enforcement prioritizes dangerous offenses, such as speeding or driving under the influence, over citing people for the equipment violations.

Last year, Prouty said, troopers stopped more than 2,400 vehicles statewide for exhaust issues and gave out more than 900 tickets and written warnings.

Fines start at $146 for first-time violators, and increase after that. Motorists pulled over three or more times pay $228 for each ticket, he said.

To report a vehicle with heavy or noisy exhaust on highways or freeways, you can call the State Patrol’s nonemergency phone numbers, which are listed on its website by district. Troopers must witness the violation to issue a ticket, Prouty said.

Q: Do SDOT and SPD sometimes ignore state and city regulations pertaining to parking near crosswalks, specifically in terms of parking within 20 feet of one? If so, why? Parking close to intersections challenges all roadway users by hindering their visibility, for instance, increasing the chance of crashes.

— James Schultz, Seattle

A: Ignore? No. Able to catch all violators? Also no.

Parking enforcement officers (PEOs) are constantly grappling with this issue as parking becomes more difficult in our increasingly congested city, according to Seattle Police Department spokesman Patrick Michaud.

The fine for parking too close to a crosswalk is $124.

“If you are parked closer than 20 feet to a crosswalk, you can expect a ticket,” he wrote in an email. “We may not catch them the first or second time, but eventually the behavior will get caught by a PEO.”

Officers gave out nearly 15,600 tickets for this parking violation in 2015 and 2016 combined, an average of roughly 650 per month, Seattle Municipal Court records show.

And you’re not alone with concerns over safety in the crosswalk zone.

“It is super important not to park in that area for two reasons,” Michaud said. “It makes it really difficult for drivers to see people as they are entering a crosswalk, creating a safety hazard. Secondly, it can make it difficult or impossible for a person with a wheelchair or walker to enter and cross the street.”

According to the city’s 2015 traffic report, the most recent available, three people died and two dozen were seriously injured in vehicle accidents at marked crosswalks in 2014. Nearly 60 percent of the year’s vehicle collisions involving pedestrians occurred in those zones.

So, drivers, if those statistics alone don’t steer you away from parking too close, maybe this will: If your parking job causes a crash, depending on its severity, you could face not only fines but possible criminal charges as well, Michaud said.

Got a question?

If you have a question or idea for Traffic Lab, send it to We may feature it in an upcoming column. (Bonus points if it’s about a pedestrian or public-transit issue.)