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A bumpy start — and lessons learned — as Somerville lines busy roads with ‘speed humps’

A few hiccups and the series of “Houdini humps” that caught drivers by surprise shouldn’t distract from how effective the new traffic calming efforts are, officials say.

Dozens of speed humps have been installed throughout Somerville, including on busy Central Street, as city officials work to deploy traffic calming measures that force drivers to slow down.David L. Ryan/Globe Staff

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SOMERVILLE — Some called them “Houdini humps.” Others complained to the city, or contacted the local news, about the damage the asphalt waves wrought on their cars’ suspensions and undercarriages.

At least one frustrated person went rogue and spray-painted squiggly lines on them to make them more visible.

So-called speed humps — mounds of asphalt installed to slow down drivers — have been popping up across Somerville by the dozen. And while many residents praise their effectiveness at reducing traffic speeds, others have claimed that when the obstacles appeared in certain parts of the city, they were difficult to see in time to hit the brakes.


Now, four years after speed humps first arrived, officials say they’ve learned a lot about how — and how not — to install the traffic calming measures, as they continue to implement more of them.

One big takeaway? If you’re going to build a speed hump, make sure people actually know it’s there.

A vehicle rode over a speed hump on Kidder Avenue in Somerville. Speed humps are traffic-calming tools intended to reduce vehicle speeds, and are being used around Somerville. David L. Ryan/Globe Staff

When Somerville’s first speed humps were installed on Powder House Boulevard in 2019, after a woman was struck and killed in a crosswalk, drivers adjusted, said Brian Postlewaite, the city’s director of engineering.

“There was a fair amount of discomfort, but mostly we could tell it was just because they were new,” he said. “Within a few months, everybody was comfortable with them and it substantially slowed traffic down on one of our speediest streets.”

That may have a lot to do with how they were installed: The humps, set up between Curtis and North streets, had been painted soon after installation with noticeable white arrows.


Two years later, after studies showed the speed humps reduced the number of cars speeding in that area from nearly half to about 5 percent, Somerville took them citywide.

That, Postlewaite said, was when the trouble started.

After new ones were built in the late spring and early summer of 2021, the city struggled to hire paint crews, which remain “in extraordinarily short supply,” he said.

For a while, the city also couldn’t source the materials for proper signage and had to borrow posts from another city department to put up signs on the curb that read “speed hump.”

“It was a real comedy of errors that our team was having to scramble with to get something out on the street quickly,” Postlewaite said. “That was something we didn’t experience in 2019.”

Almost immediately — “in days, not weeks,” Postlewaite recalled — the complaints started rolling in.

Addressing reports of drivers traveling at full speed over a hump, only to be surprised when their vehicles suddenly bounced over it, rose to the top of the priority list at his department’s weekly meetings.

On Central Street in April, Somerville residents noticed that a driver had lost control of their vehicle while traveling over an unmarked hump — presumably at high speed — before crashing into one of the bright yellow signs warning about it.

Mary Mangan, who snapped a photo of the battered sign, said she wasn’t surprised by the driver’s mistake. She, too, had a close call with one of the new additions to the streetscape that same day.


“They weren’t painted properly. And there was so much activity on that street — walkers, kids at a nearby park, cyclists — that I was paying attention to the people and not the pavement,” Mangan, who is pro-speed hump, said in an email. “It worked out ok for me because I’m not a speed demon anyway, but it was surprising.”

Many of the speed humps installed in Somerville in recent months did not have markings painted on them, and some drivers said the signs installed nearby weren't enough to warn about the bumpy ride that ahead. In April, a driver on Central Street appeared to have collided with one of the signs. Mary Mangan

That same month, during a segment on CBS News, a neighbor aired concerns about his truck’s exhaust sustaining $1,600 in damage from an unmarked speed hump on Kidder Avenue. He said he’d heard some people joke about tagging the speed humps with spray paint so they would stand out more.

Soon enough, someone did.

Photos posted in May on a Reddit page for Somerville residents showed the Central Street speed humps marked with crudely drawn yellow lines that looked like the teeth of a traffic monster.

“I don’t know who spraypainted the speed bumps on Central St.,” a Somerville resident wrote on the site. “But thank you.”

Drivers in Somerville complained that they didn't notice newly installed speed humps in the city before it was too late to slow down. In May, someone took matters into their own hands and drew squiggly marks on the humps lining Central Street. Patrick A.

Advocates for safer streets, meanwhile, took speed humps’ bumpy start as proof they’re needed.

After all, drivers won’t have trouble if they travel at an appropriate speed through the most densely populated city in the state, said Tom Lamar, chair of the Somerville Bicycle Committee.

“I’d love people to just get used to driving at no more than 15 miles an hour or so when they’re on local roads in the city,” Lamar said. “Think of every street as somewhere that might have speed humps, or that might have kids needing to walk across the street on their way to school, and default to driving at a very low speed.”


The speed humps are part of the city’s Vision Zero initiative, which seeks to eliminate serious or fatal traffic collisions and calls for making roads safer with features like raised crosswalks, crossing islands, neighborhood traffic circles, and curb extensions.

Speed humps have become an important component of other cities’ road safety efforts, including in Boston, where officials plan to install as many as 1,500 of them over the next three years. (In nearby Cambridge, the city uses raised crosswalks, which are designed to accomplish the same goal.)

Of all the traffic calming measures available to city planners, few are as likely to catch people off guard as speed humps.

So moving forward, Somerville has made changes to its installation protocol.

For one, officials said, signs are now set up at the sites of new humps a few days before the asphalt is even poured. That way, neighbors get a heads up that one is coming to their area.

Next, as soon as the hump is formed, crews are instructed to immediately put down temporary reflective tape until crews can add permanent markings.

To take it an extra step, the city marks humps with diagonal yellow stripes, in addition to the standard white arrows.


According to the city, they should be all but impossible to miss.

“We have a 20 mile per hour speed limit,” Postlewaite said. “If you’re driving the speed limit and you don’t see them, I really fear for what else you’re not noticing.”

Spencer Buell can be reached at Follow him @SpencerBuell.