Shortcuts and the Best Route
Urban designers know the frustration of watching unofficial trails sprout on perfectly manicured lawns. These are desire paths: the physical evidence of the shortest distance between two points. But, while a straight line is efficient, it isn’t always optimal. The “best” route is a shifting balance of speed, energy, and the unknown. With your team, consider the logic of the shortcut and the science of the scenic route. How do humans, animals, and even slime molds decide what way to go? Should we always follow the path of least resistance?
- Traveling salesman problem | vector-based navigation | explore-exploit problem
- Route elasticity | Braess’s Paradox | dead reckoning | the Steiner Tree Problem
Look at the corner of any campus lawn and you'll find it: a worn dirt line cutting across the grass where the paved path took the long way. These 'desire paths' are the physical record of thousands of people each deciding the shortest distance between two points — and the topic asks whether the shortest way is really the best one.
Key concepts
- Desire Path
- An unofficial trail worn by feet where people actually want to walk, cutting against the designed route — crowdsourced evidence of the truly preferred path, sometimes well-trodden enough to show on Google Maps.
- The Traveling Salesman Problem
- The puzzle of finding the shortest route visiting a set of points once and returning home — simple to state but monstrously hard as points multiply, enough to defeat even supercomputers.
- Braess's Paradox
- The counterintuitive finding that adding a new road can make everyone's commute slower, because individuals all grab the tempting shortcut and clog it.
- The Explore-exploit Problem
- The constant choice between the route you know works (exploit) and a new one that might be better or worse (explore); take the known shortcut every day and you may never find the faster way.
What to know
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01
Efficient is not the same as optimal: the straightest line ignores energy, safety, and the value of what you'd pass — so a desire path can be the shortest route and still not the best one.
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