Public furniture, large art installations and trees can all make cities more livable. They can also make cities safer.

Researchers, urban planners and community activists say that city design is one of the best ways to ward off the growing threat of terror attacks that use motor vehicles as a weapon, the most recent of which occurred in New York City last week. The approach — which separates cars from pedestrians and cyclists by using physical barriers that are capable of stopping a moving vehicle and that can also function as environment-enhancing installations such as benches or planters — allows cities to help protect people and buildings while maintaining and even enhancing a city’s everyday function as a place to live and work.

Some groups have called for increased surveillance and arming police with new technology in order to prevent future attacks. But those tactics come with civil rights concerns or rely on technology that doesn’t yet exist. Meanwhile, using urban design to make cities safer has the support of a number of groups, including pedestrian advocates, urban planners and security experts. That’s partly because the changes can make cities safer, even in the absence of a terrorist attack.

The increasing frequency with which people have been driving into crowds as a tool of terror may be related to a 2010 article that promoted the tactic in a magazine purportedly linked to Al Qaeda. More recently, ISIS-linked publications have also latched on to the tactic. In the last few years, vehicles have been used for attacks in several European cities, including London; Nice, France; and Barcelona, Spain. On Tuesday, an attacker drove a truck down a bike path in lower Manhattan, striking pedestrians and cyclists and killing eight people.

Vehicles are an effective weapon, terrorism experts say, because they require no special skill or training to operate, and they are both easy to get and ubiquitous — seeing a truck drive down a street doesn’t set off any alarm bells for law enforcement or bystanders. That has led security experts and urban designers to look for ways to physically separate the spaces where cars travel from areas designated for cyclists and pedestrians.

These barriers can be effectively incorporated into spaces so that they aren’t just security tools, according to Jon Coaffee, a professor at the University of Warwick in England who has written about urban design and security. In fact, they already are. These devices appear in cities all over the world, but even city dwellers who see them every day may not realize their purpose. In the academic world, design solutions that serve a secondary purpose are labeled as having increased “acceptability” compared to the concrete walls and similar temporary barriers that are often erected to protect buildings or spaces. People like them because they improve a city space without making it feel like a police state.

Cities have long put security barriers around government buildings. After the Oklahoma City and World Trade Center bombings, when officials were particularly concerned about truck bombs, barriers were installed around a number of important structures. Concrete posts at an airport in Glasgow were credited with preventing deaths during one of these attacks in 2007.

With terrorists attacking “soft” targets — places without a lot of security, like the Christmas market in Berlin in 2016 or the bike path in New York City last week — questions have arisen about how cities can protect a variety of spaces without impeding their daily function. Concrete slabs and other drab or militaristic-looking barricades are not necessarily embraced by the public: Temporary concrete cubes placed in Melbourne, Australia, after an attack there became the focus of a renegade art installation run by residents and artists who found the barriers ugly.

While it’s impossible to fully protect every space where people congregate, the goal, wrote Coaffee, is to make spaces safer without making them feel like they were built for security instead of urban living. “The predominant view that is emerging is that security features should, where appropriate, be as unobtrusive as possible,” he said in an email. That means focusing on making installations aesthetically and functionally pleasing.

Take, for example, the fortified concrete letters spelling out ARSENAL outside of the stadium where the soccer team plays in London, a favorite place for fan photos, according to Coaffee. Or the heavy concrete planters placed around small parks and seating areas in New York City that mark the boundaries of pedestrian areas, but also stop vehicles from being able to enter.

Cycling and pedestrian advocates have called for an increase in these kinds of installations for years, well before the recent uptick in vehicle-based terrorist attacks, since they can prevent accidental injuries as well, said Caroline Samponaro, deputy director of Transportation Alternative, an organization that has promoted biking and walking in New York City since the 1970s. She noted that people are hit by cars every day in New York City — by the end of September, 97 pedestrians and cyclists had died and more than 10,000 had been injured in crashes in 2017 alone, according to city data.

Samponaro’s organization has advocated for the use of bollards, which are essentially posts used to control traffic. They can be made of concrete, plastic or other materials, though those made of lightweight material can only guide traffic, not stop cars from entering protected areas. Bollards can be permanent, removable or retractable. They come in a variety of designs and styles to match the needs of a space. They can be placed at street corners to force cars to turn on a more narrow radius, which slows vehicles down, or across entryways to spaces designated for bicycles and pedestrians.

Bollards were broadly promoted after 2006, when cyclist Eric Ng was killed by a drunk driver who drove through a different section of the bike path where last Tuesday’s terror attack occurred. A task force was assembled, and bollards were recommended. But at the time of the attack, there were no barriers at many of the path’s entrances.

Samponaro stressed that although these types of attacks draw more attention than everyday accidents, city design solutions shouldn’t be handed over to security experts. “The goal shouldn’t be to create a police state based on fear. It’s possible to have thriving, dynamic, accessible spaces for people,” she said. “That doesn’t mean a threatening environment.”