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In Cambridge, heeding a new traffic signal

This yellow blinking arrow signal was installed to end motorist confusion near the CambridgeSide Galleria.

Wendy Maeda/Globe Staff

This yellow blinking arrow signal was installed to end motorist confusion near the CambridgeSide Galleria.

It’s the transportation craze that’s sweeping the nation — well, sort of — and Cambridge is at the vanguard: the yellow blinking arrow traffic signal.

In a February installment of this column, a driver complained about an intersection near the CambridgeSide Galleria that had caused him and his wife confusion. At the point where Cambridgeside Place, a two-way street, crosses First Street, drivers are faced with a one-way street bringing traffic in their direction.

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The conundrum: For years, the Cambridgeside Place drivers have been greeted with green arrows facing opposing directions. The green left-hand arrow gives people the impression they have the unfettered right-of-way for a left turn — not the right message to send, because left-turning cars must yield to oncoming traffic from Charles Street.

But swapping the light for a regular circular green signal could lead drivers to think they had the option of proceeding straight through the intersection and head the wrong way down the one-way street.

In this space, a different alternative was proposed: the little-known and seldom-used yellow flashing arrow, a traffic control measure that was approved for use by the federal government less than a decade ago. The blinking arrow is meant to tell drivers to proceed with caution and yield to oncoming traffic.

The yellow blinking arrow is slowly making its way across America. Just in the past few weeks, transportation officials in Amarillo, Texas; Olathe, Kan.; and Hoschton, Ga. have installed them.

When the suggestion initially reached the inbox of Jeffrey R. Parenti, Cambridge’s principal traffic engineer, he had one thought: Not a chance.

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“I was skeptical,” Parenti said this week. “I’ve never seen it myself, and I just thought, I don’t know, it seems like it wouldn’t work.”

That intersection has plagued Cambridge traffic engineers for years. For starters, it’s not well designed, Parenti said. In a perfect world, he said, engineers could simply reverse the direction of one-way traffic on Charles Street, but that might not fly with residents used to the street.

“Not many people would build an intersection like this, but sometimes you play the hand you’re dealt,” Parenti said.

He took a closer look at the entry for the yellow-arrow traffic signal in the Manual of Uniform Traffic Control Devices.

“I read through [the manual], and it seemed simple, much more simple than I’d thought,” Parenti said.

He gave the OK to install Cambridge’s first such traffic signals. The new signal heads, which cost several thousand dollars, debuted Tuesday, and Parenti has been monitoring the intersection. He expected annoyed reactions from drivers, along with a barrage of complaints at his office.

But so far, it appeared that traffic has flowed safely at the intersection and there have been no angry phone calls.

“I was surprised at how well drivers responded,” Parenti said. “It is always a risk to put something new in the street that drivers have never seen before, and this is a condition that I’m confident a large majority of drivers are not familiar with. I expected honking, confused looks and gestures, and long queues of idling vehicles, especially on the first day.”

Now, Parenti says he’s squarely on the side of the new control device. It works, he said, because it causes drivers to stop and think about the traffic situation with which they’re faced. Mostly, he said, traffic signals are meant to give unequivocal messages about what they’re supposed to do, which allows drivers to largely operate on autopilot. But sometimes, he said, it’s better for drivers to be a little unsure about how they’re supposed to proceed, such as at a busy intersection next to a mall, with lots of pedestrians, many of whom are only occasional visitors.

“What I did see [at the intersection] was that drivers appeared more tentative . . . which is exactly what we want at a location with an unusual one-way condition,” Parenti said.

Call it controlled confusion: add something new and unfamiliar, and people pick their heads up and pay better attention to their surroundings.

“We want people to think cognitively about their surroundings more,” Parenti said.

Though they are not a common sight in the Commonwealth, the Cambridge light is not the first in the state. The Massachusetts Department of Transportation installed one in Lenox in early 2012, after a series of crashes led engineers to rethink an intersection in the town.

They’re considering adding a few more in Holyoke later this year.

Readers, have you encountered a blinking yellow arrow while driving? What did you think?

The Ride still stops in Downtown Crossing

Downtown Crossing has had a pedestrian-only zone since 1979, but for years, restrictions on car traffic have been waived for The Ride, the T’s door-to-door transportation service for people with disabilities.

That is, up until two weeks ago. Earlier this month, Boston police handed out a handful of warning tickets to drivers of The Ride idling in Downtown Crossing as they waited for pickups or after they dropped people off.

The tickets did not require payment, but paratransit dispatches, fearful that drivers would face expensive citations if ticketed again, began to inform customers that The Ride would no longer be able to deliver them to addresses within Downtown Crossing’s pedestrian zone.

James White, chairman of the MBTA’s Access Advisory Committee, caught wind of the problem and quickly went on the offensive, contacting multiple state and municipal agencies to get the matter sorted out.

Door-to-door service is mandated by the federal Americans with Disabilities Act, he said, and people with disabilities dropped off blocks from their destination risked tripping or getting their wheelchairs caught on the uneven bricks that spread across the walking plaza.

Besides, White pointed out, commercial vehicles are allowed to make deliveries in the mornings, and taxis can queue in the pedestrian zone as they wait for pickups during the evenings.

“You can’t just drop someone three blocks away. You have to escort them all the way to the door where they’re going. That’s ADA-required,” White said.

White said he believed the tickets were probably the doing of an overzealous police officer unfamiliar with the protocol of the plaza and he expected that “clear heads will prevail.”

Indeed, within a couple days, police backtracked and canceled the citations. The Boston Transportation Department doubled-down on that view, saying that the tickets were “a one-time issue that has been corrected” and that The Ride vehicles are permitted access within the zone.

Still, White says he is pushing for signs to be added to the “no parking” poles in the area that make it clear that vehicles dropping off and picking up disabled passengers are allowed within the no-parking zone.

“We want to make sure that there are no misunderstandings in the future,” White said.

Martine Powers can be reached at martine.powers@globe.com. Follow her on Twitter @martinepowers.

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