The High-Tech Way to Avoid Long Lines

Sometimes a five-minute coffee run can turn into a frustrating half-hour wait, depending on how many caffeine cravers are in line ahead of you. But what if you could know how crowded a place is before heading out for a latte, or a trip to the DMV, or even waiting in a hideously massive line at Trader Joe’s? That’s the concept behind Density, a new device that detects foot traffic in real time.

Here’s how it works: Businesses place Density—which comes in the form of a tiny black box, below—on their door frame, somewhere around hip height. Using infrared distance sensors, Density detects when someone has entered or exited the building. ​The device counts the number of customers who pass through each day, or even how many patrons are inside at a given moment. (A guest’s identity is entirely anonymous, and Density cannot capture any information about him.)