A quarter of a million people pass through Denmark's busiest train station each day.
Many who use Copenhagen's Nørreport Station are on foot and on bikes, navigating their way around the trams, buses and cars that also use the surrounding area.
Before a redesign of the station and its surrounds, the combination was not working. It was described by the firm that revamped the space as "a chaotic island surrounded by traffic" which neglected pedestrians and cyclists.
As designers sought to unravel the chaos and create a better, safer space, they paid careful attention to how people were already using the area.
Dan Stubbergaard, founder of Danish design firm Cobe, described the process.
"In wintertime, organic pathways emerged in the snow created by people's movements in and around the station, clearly showing us where there was a need for passages, shelter and bicycle parking," he said.
What emerged was a renewed, functional public space that connected well to other parts of the city.
The ground-level infrastructure of the underground rail hub consisted of floating, circular roofs above glass pavilions, surrounded by sunken bicycle beds encircled by the paths that mimicked those made in the snow.
Mike Harris, an urban design researcher at the University of New South Wales, said the success of the Danish project showed how paying attention to people's behaviour resulted in better city design.
Dr Harris said with people increasingly living in built-up environments, those designing urban spaces were examining desire lines, or desire paths, more frequently.
A desire line, or desire path, is an unplanned trail that forms as a result of traffic, either by humans or other animals, and often veers away from conventional paths.
"The idea behind the desire line is that it is really about the path of least resistance," Dr Harris said.
"People take it simply because it's easy.
"That's human nature with so many things. People will tend to choose the option that is the easiest."
In recent years, sharing examples of these organic paths at odds with planned paths has become popular online.
Dr Harris said in many cases, desire lines showed those who planned or designed a space "fundamentally got it wrong".
"It's just simply that they weren't cognisant of how people actually want to use that space," he said.
UK nature writer Robert Macfarlane encapsulated the appeal of desire lines when he described them as "free-will ways".
"[They are] paths and tracks made over time by the wishes and feet of walkers, especially those that run contrary to design or planning," he wrote.
Dr Harris as desire lines sparked interest among the broader public in Australia and around the world, those designing public spaces were increasingly paying attention to them.
"There are projects that really explicitly demonstrate how they have analysed how people move around the space before they redesign it," he said.
Dr Harris said optimising public spaces to suit pedestrians and cyclists was sometimes at odds with the efficient movement of cars and vehicles.
But he said people's reliance on getting around their local neighbourhoods during the COVID-19 pandemic had helped prompt a rethink, with making pedestrian-friendly streets a greater priority.
"I think during COVID there was a lot of reassessment about public space and streets and active transport," he said.
People's desire lines not clear cut
Researcher Elli Irannezhad, who is working on a project analysing desire lines at two busy Melbourne intersections, said using people's behaviour to design better public spaces was complex.
The project, commissioned by Victoria's Department of Transport, has involved collecting data on people's behaviour at the intersection of Russell and Bourke streets, and a tram stop on the Southbank side of the Queens Bridge.
After a study done in Sydney analysed people's desire lines at a central park, the Melbourne project was commissioned through iMOVE, a national centre for transport and mobility research and development.
"This study … is looking at people's behaviour when crossing the street, and particularly using public transport stations," Dr Irannezhad said.
"We know, for instance, that in the CBD or in crowded areas, when people get off the bus or train, then they may use the shortest paths or so-called desire lines to get to the station, the other side of the road or the coffee shop versus designated safe paths.
"What prompted us to do the study was [to understand] the demographic characteristics of people, as well as the environmental attributes of the site."
The University of New South Wales lecturer said both design and built environment and demographic factors were very influential on behaviour.
That means factors like whether it is raining or sunny, whether someone is young or old, or if they are carrying something heavy or pushing a pram can change how they behave.
She said unlike in a park, in a public transport context, the use of shortcuts by people who were in hurry to catch a tram or get out of poor weather conditions could be dangerous.
"If you're looking at public transport stations in the vicinity of intersections, then if people are using shortcuts rather than waiting for the signal or using the zebra lines, then that means their safety will be at risk," she said.
Dr Irannezhad said she hoped the preliminary study would lead to further work to examine the implementation of "nudges" around public transport hubs, to analyse how they influenced people's behaviour.
"The ultimate purpose is basically setting up some recommendations for designers … so if you make the designated safe path more attractive … it may prompt people to use those safe paths," she said.
Despite designers' increasing focus on desire lines and desire paths, particularly to improve safety, Dr Harris said they did not necessarily always need to be incorporated into built areas, and could be left as a part of the city that was "a bit informal and a bit messy".
"With formalised desire lines, you actually need to make sure it is actually the easiest way to go, and it also comes down to context," he said.
"So at a train station where you've got so many people walking through, you wouldn't want this charming goat track because it's just not going to be practical and you've got accessibility issues.
"But then in some parts of the city you want surprise and mystery … sometimes allowing things to emerge as they will."
