After a leisurely lunch in Barcelona, tourists and locals ambled down the city’s famous pedestrian thoroughfare, La Rambla. Visitors paused at kiosks to pick up postcards for friends back home, while elderly residents sat on benches, swapping stories in the late afternoon light. Suddenly, a white van swerved into a crowd at Plaça de Catalunya, then raced down La Rambla, plowing into pedestrians.

The violence in Barcelona on August 17 and in nearby Cambrils the following morning is the latest in a string of deadly attacks in Europe and the U.S. involving cars, trucks or vans as weapons of terror. Earlier this month, a man sped a car into a crowd protesting white supremacists in Charlottesville, Virginia. In April, a truck smashed into shoppers on a busy street in Stockholm. There have been three deadly vehicle attacks in London since March. Last year, a tractor-trailer careened into a Christmas market in Berlin, and a 19-ton delivery truck plowed through Bastille Day celebrations in Nice.

Using cars to incite terror isn’t new—not even in the West. But now Daesh, who claimed responsibility for the attacks in Spain, has revived the strategy, urging followers without access to conventional weapons to find alternative means of violence: “Smash his head with a rock, or slaughter him with a knife, or run him over with your car…”

These incidents, like other acts of terror, have turned lively city streets into sites of chaos and bloodshed. But by wielding cars and trucks as instruments of mass murder, these acts are turning vehicles—ordinary elements of our urban landscapes—into a ubiquitous and terrifying menace. And it’s distorting how we perceive and inhabit public spaces.

Distorting Perception

Cars have always posed a certain level of danger. Each year, nearly 1.3 million people are killed and another 20 to 50 million are injured in car crashes around the world. Meanwhile, the probability of being killed by a terrorist in the West is relatively low: one expert argues that an individual in France is 27 times more likely to die in a car accident than a terrorist attack.

But statistics do little to quell our anxieties. The collective trauma of recent vehicle-ramming incidents has made many of us wary of the cars, vans and trucks we pass each day. Walking along a congested seaside promenade, dining at a sidewalk cafe, standing before a crosswalk: today, even the most mundane acts of daily life can provoke a sense of unease or trigger a sudden rush of adrenaline.

How can residents and vacationers enjoy Europe’s parks and plazas when, at any moment (or so it seems), a car may deliberately veer into a crowd of partygoers or a mother pushing a stroller?

Transforming Public Space

In response to recent events, cities across Europe are erecting physical barriers to shield pedestrians from potential acts of terror. After a white van mounted the curb on London Bridge in June, authorities installed concrete and metal fences between the road and sidewalk on several bridges. The morning after the attack in Barcelona, residents in Madrid woke up to find large concrete flowerpots around la Puerta del Sol, the city’s main pedestrian square. Now, cities across Italy are also placing bollards—concrete barriers—around famous landmarks.

While these anti-terror structures may protect pedestrians from vans and trucks, they may also stoke anxieties of their own. Concrete barricades may serve as bleak reminders of past violence or hint at violence yet to come. They may also threaten the aesthetic, cultural and historical integrity of city squares and landmarks, making tourist hotspots look like security checkpoints or fortified military outposts. They may even limit the ability of visitors and residents to move around freely. In London, for instance, the concrete barriers sparked controversy when cyclists complained that they were causing dangerous traffic conditions.

How can European cities strike a balance between maintaining the beauty and culture of their public spaces while keeping people safe? In some cities, like Bristol, British officials have installed bollards that double as creative street furniture or public art. Large flowerpots already line the pedestrian square in front of New York’s famous Flat Iron building. Last week, Italian architect Stefano Boeri suggested that city officials plant trees to guard open spaces in an eco-friendly way.

Despite ongoing efforts to securitize our cities, many of us in Europe still nervously eye the truck parked on the corner, or stand discreetly behind a pole or streetlight while waiting to cross the road. And with each passing, fearful thought, it’s clear the terrorists have made their mark on survivors.

On the other hand, in the wake of the attacks in Spain, crossing the street or having a drink on an outdoor patio can be small yet powerful acts of defiance. They are simple ways through which we can reclaim our cities—and keep our collective spaces lively and inclusive—even in the face of an ever-present threat.