New 25 mph Limit: “Essentially No Impact”?

By Chris Wangler
October 4, 2023

Will a lowered citywide speed limit actually slow down drivers? Waltham’s traffic engineer didn’t think so back in 2019—and he’s still skeptical.

Recently the city’s traffic commission voted to reduce the citywide speed limit to 25 mph, following a growing number of cities and towns in the area. The new limit does not affect six main thoroughfares in Waltham (Bear Hill Rd/Second Ave, Main Street, South Street, Lexington Street, Beaver Street and Forest Street).

At the last Waltham Traffic Commission meeting, member Mike Chiasson said “we had people coming in here every week asking for reduced speeds” in their neighborhoods.

Ward 8 city councilor Cathyann Harris told commissioners her constituents have repeatedly approached her about speeding. “I have many pending requests, hoping this passes today,” she said.

But Chiasson explained that studying the speed patterns on their roads could actually result in increased speed limits, not lowered ones.

So the idea was to lower the citywide limit to address recurring concerns, especially since a new state law allows cities and towns to opt into the lowered limit in thickly settled areas like Waltham.

So will a reduced 25 mph speed limit actually slow drivers down? 


In a clip from the initial discussion of the matter in 2019 [see above], Waltham traffic engineer Mike Garvin didn’t hold back, saying the data shows that people drive at speeds they deem comfortable, regardless of signage.

“Lowered speed limit signs without any actual traffic calming engineering are really just a political action instead of a safety improvement,” he said. 

“They would allow elected officials and members of this traffic commission to claim they have done something to address speed, but the truth is speed limit signs have essentially no impact on the speed of cars on a road.”


Garvin added that only traffic engineering can realistically affect behaviors. For an example, check out the new speed bumps on roadways that intersect the new rail trail.

When asked about his current feelings recently, Garvin remained doubtful about the 25 mph signs, even though he ultimately recommended the change to the commission. He said police enforcement could help.

“With the lower speed limit, the fines associated with any speeding tickets that the police issue are higher, which should serve as somewhat of a deterrent for those who want to drive fast,” he said. “So long as the police department follows up with enforcement.”

File photos