Can optical illusions trick drivers into slowing down?

In West Vancouver Canada, a nonprofit installed a 3-D decal on a road near a school to raise awareness about drivers speeding through school zones.The Community Against Preventable Injuries

Here’s a creative way to get speeding drivers to slow down: Deceive them and then scare the heck out of them.

A handful of cities around the world have painted optical illusions on roadways — think raised beams and even images of children — that appear, at first glance, to be blocking motorists’ paths.

The idea is to get lead-footed drivers to put on the brakes. After all, if you think you’re going to hit a steel beam or a little girl chasing her ball, you’re going to slow down.

Popular from New Delhi to a tiny town in Iceland, the most prevalent of these illusions are the striped lines made to look like they’re three dimensional blocks floating in the middle of the road. Similarly, in London, officials have painted what look like speed bumps, even though the road is flat.

And, in Canada, a 3-D image known as “Pavement Patty” that depicts a girl chasing a ball into the street was temporarily painted on a road near a school to raise awareness about cautious driving.

But could these cartoonish images improve roadway safety in Boston? Local officials are intrigued.

Officials in the other countries say the markings have contributed to better driving. And while they can add an element of surprise, officials in other locations said they haven’t seen any reports of drivers stopping so quickly that they’ve caused an accident.

New Delhi

In New Delhi, India, 3-D crosswalks have gotten drivers to slow down and pay better attention.Yogesh Saini / Delhi Street Art

Initial measurements by the city’s traffic police found speeds dropped by 15 percent in the areas where 3-D crosswalks were installed last year, according to Yogesh Saini, founder of Delhi Street Art, which painted the crosswalks on the municipal council’s behalf.

“As people got accustomed to seeing them, the speeds appear to have crept up some,” Saini added in an e-mail.

Even so, he said, there are clear benefits.

“They surely created an awareness in the public,” a reminder to drive safely, he said. And, drivers are more likely to notice pedestrians because “they appear to be walking on floating concrete blocks.”

Saini said there are now nearly 20 such crosswalks across New Delhi.

But he acknowledged there’s a potential downside — a problem that has occurred elsewhere, too.

“Pedestrians started using the crossings to take selfies when there was no traffic,” he said, though “this trend now appears to have tapered off.”

Ísafjörður, Iceland

The scenic town of Ísafjörður, Iceland recently installed a 3-D crosswalk on a centrally-located street.Ralf Trylla / Town of Ísafjörður, Iceland

In this small, scenic town, a recently installed 3-D crosswalk on a centrally located street certainly got people talking.

Officials said they don’t have statistical proof, but believe it is has caused drivers to slow down, just as it did in a major city halfway across the world.

“We feel like it did,” said an e-mail from Gautur Ívar Halldórsson, managing director of Vegamálun GÍH, the company that installed the Iceland crosswalk.

The 3-D crosswalk costs only a bit more than a standard one and officials there plan to install more, using different colors and effects.

But as in New Delhi, the effect may be waning.

“For sure drivers are getting used to it and (probably) don’t pay too much attention to that crossing in the long run,” Ralf Trylla, the town’s environmental officer, wrote in an e-mail.

Even so, “when they drive over it, they always get reminded that there is something different than just a normal crossing,” said Trylla.

London

In London, officials have painted what look to drivers like speed bumps, even though the road is flat.Transport for London

A series of markings that look like speed bumps — officials call them “2-D road cushions” — were first tested in late 2014.

The trial period showed “average speeds reduced by 3 m.p.h. nine months after installation,” said Danny Keillor, a spokesman for Transport for London, which oversees the area’s transportation network.

Encouraged by those results, the agency expanded the effort. There are now 45 road cushions installed across roads it manages around London, he said.

“Even if some drivers become accustomed to 2-D road cushions, if one driver slows for the 2-D cushions, they will help slow all traffic behind them,” Keillor said.

West Vancouver, Canada

A different angle than the photo at the top of this story, this shows how the 3-D effect of the decal painted in West Vancouver, Canada — like the markings used in other cities — was only visible to approaching drivers at certain distances.The Community Against Preventable Injuries

In Western Canada, officials took the optical illusion even further when a nonprofit called The Community Against Preventable Injuries installed a 3-D decal on a road near a school to raise awareness about speeding in school zones.

The decal, called “Pavement Patty,” looked like a girl was in the street chasing a ball. It was installed temporarily during the 2010 back-to-school season, said Jennifer Smith, the organization’s senior program manager.

Because it was a short-term initiative, the nonprofit didn’t try to measure whether drivers slowed, Smith said.

The goal “was to highlight the issue in a novel way, and generate public conversation,” she said via e-mail. “The idea behind this installation, and all of Preventable’s work, is to get people’s attention and get them thinking about their behavior.”

Smith said the decal was “highly successful in generating conversation in the community, the local media, and garnering attention worldwide. Although this installation was done in 2010, Preventable still receives questions about the decal to this day.”

She said the public’s response was “overwhelmingly positive.’’

“Some people expressed concern that the decal would startle or distract drivers, potentially increasing the risk of a crash,” she added.

But, as with the crosswalk illusions elsewhere, no collisions occurred, she said.

United States

So could these illusions work here?

Officials from several national transportation safety organizations said they were not aware of any currently in use in this country. And some experts expressed skepticism, saying the concepts at least require further study.

At least one, albeit limited, study has been done in the United States. A 2012 study by a Western Michigan University graduate student looked at the effects of adding lightning bolt-shaped, 3-D markings just ahead of a pair of crosswalks in Chicago. It found the markings initially caused drivers to yield more often, but the effects wore off soon after.

In the United States, experts said such markings violate existing national roadway standards governed by the Federal Highway Administration. But the agency can grant approval for such ideas to be tested and approved.

Federal highway agency officials said they were aware of the use of such road markings in other countries but were not aware of any proven benefits compared to standard markings.

But others, including Boston’s transportation head, said the ideas seem promising.

“They are all really terrific elements in terms of roadway design,” said Boston Transportation Department Commissioner Gina Fiandaca. “We’re really intrigued, and communities really welcome these innovative designs.”

Fiandaca said city officials will review the markings more, and are open to asking the federal highway agency for permission to test them in Boston.