So-called "Jersey barriers" — long low concrete walls designed originally to provide traffic separation and crash protection on highways — are becoming a common sight in Toronto.

Days after the Yonge Street attack, they've begun popping up around Union Station, the Rogers Centre and other high-traffic public places as a precautionary measure to deter vehicle attacks.

It's definitely not a use for which they were intended, but it's better than nothing, say city staff.

In an email to CBC Toronto, Jennifer Wing, a senior communications advisor with the City of Toronto, says the barriers went up at Union Station in consultation with Toronto Police Service, but there was already a plan for permanent physical security measures there.

The barriers, now seen around Union Station and the Rogers Centre, are meant to act as a deterrent to vehicular attacks. (CBC)

"While work on the permanent design is being carried out, there were already plans in place to install interim mitigation measures later this spring," says Wing. "The discussion that is being had now is if whether the jersey barriers will come down or remain in place until the interim mitigation measures, which are designed to fit in with the streetscape, are installed within the next month or so."

The April 23rd attack was the latest in which a vehicle was the weapon used to incur mass casualties, and cities worldwide have been trying to find effective ways to prevent deaths and injuries.

Skepticism towards effectiveness

At a vigil for the victims held at Mel Lastman Square, Sean Lee, 18, isn't so sure barricades would help prevent future attacks.

"If someone were to do that again, if there were concrete barriers, wouldn't he just kill people in another way?" he says.

Keisha Johnson says Toronto has joined a not so enviable international club of cities where vehicles have been used as blunt weapons to kill.

"It's naive to think it wouldn't happen here," she says. "I view the street differently now — it makes me more aware of my surroundings."

Keisha Johnson and Sean Lee attend a memorial in Mel Lastman Square for the victims of Monday's van attack. They aren't sure Toronto should follow the lead of other cities around the world that have erected barriers in the wake of similar attacks. (Philip Lee-Shanok)

11 vehicle attacks since 2016

Since 2016, there have been at least 11 such vehicle attacks, including in cities like New York, Nice, Berlin, Stockholm and London, and in most cases some sort of vehicular barrier have gone up in the aftermath.

After 12 people were killed and at least 48 injured at a Christmas market attack in Berlin in 2016, authorities installed concrete and metal bollards in many Germany cities.

Similarly, on Bastille Day 2016 when a truck attack on a beachfront promenade in Nice killed 86 people and in England after a vehicle rammed pedestrians on London Bridge June 4, 2017, vehicle barriers were seen as the solution.

"That might work in some places and Europe has done this quite effectively," says former Toronto chief planner Jennifer Keesmaat.

After two vehicle attacks in 2017, New York Mayor Bill de Blasio announced the installation of thousands of bollards around the city to protect pedestrians.

Better urban design a solution, former chief planner says

But Keesmat cautions against creating a ring of steel and concrete here.

"Throwing up barricades around the city is not in our DNA. It's not who we are and, quite frankly, I don't think that's going to make us much safer," she says.

Giant planter in Yonge-Dundas Square does double duty as a crash barrier. (Philip Lee-Shanok/CBC)

Instead, she says better urban design, including street furniture, concrete tree planters, seating areas and public art installations, could act as a deterrent. Keesmat points to the long low concrete flowerbed along St. George Street on the University of Toronto downtown campus as an example of how high-pedestrian areas can be separated from traffic.

However, Barbara Robinson, an infrastructure expert and president of Norton Engineering in Kitchener, says safety barriers can be very expensive.

For example, New York City budgeted $50 million US for metal bollards in midtown — or more than $30,000 US each.

"But of course we cannot possibly put this kind of design on every street. It would just be prohibitively expensive," she says.

Robinson says adding bollards in downtown Kitchener also added to the city's operating budget.

"Clearing snow from downtown is very expensive because it has to be done by hand now. You can't just run a big machine down the sidewalk."