Forget about witches and vampires and zombies. You may face something scary on Halloween, but it’s not likely to be fanged or undead. Try gridlocked, suggests Gary Hustwit, director and producer of “Urbanized,” a new documentary about the design of cities. The most terrifying problem metropolitan areas face, according to his research around the globe: traffic.

Figuring out how to move people quickly has always been a puzzle for urban planners. It only got harder when they started building cities for cars.

“The idea that every individual needs an automobile, when you step back and look at it, it’s ridiculous,” says Hustwit, who will speak after a sold-out screening of “Urbanized” at E Street Cinema Monday night. The focus, he says, has to be on improving alternative forms of transportation instead of just adding roads and widening highways. “The city needs to invite the behavior it wants,” he says.

The film zeros in on Bogota, Colombia, as a model for this kind of change. A decade ago, the city introduced TransMilenio, a bus rapid transit system that serves the purpose of a subway but uses dedicated bus lanes rather than rails. “It’s common sense and democracy that a bus holding 100 people deserves 100 times the road space as cars holding one person,” Hustwit says, paraphrasing the city’s former mayor in the film.

“Urbanized” is different from Hustwit’s other design docs, “Helvetica” and “Objectified,” in that it features regular citizens. You don’t need to be a professional planner to shape a city. You just have to live there. An artist in New Orleans interviewed in the film created stickers that say “I wish this was” with a large white space underneath. She’s placing them all over and inviting passersby to write in their fantasies. This simple project accomplishes precisely what Hustwit aims to do with the movie: Encourage people to think about the kind of city they want to live in.

If you’re wondering how D.C. comes across in the film, it doesn’t. Although Hustwit says our fair city was repeatedly brought up as a “bad example of urban design,” it didn’t make the final cut. But Washingtonians will recognize the issues raised by the film. “We all have to get around,” Hustwit says.

Even though some places have taken greater strides than others, he adds, “there’s no perfectly designed city. It doesn’t exist. That messiness is what makes them incredible social experiments.” And fascinating documentary subject matter.