Smart card taps track clogs on London’s Tube
![A map of the London tube](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2015/04/ticker_ay_londonunderground.jpg?fit=860%2C460&ssl=1)
Smart card data are helping to unravel which stations in the London Underground system, above, may be most vulnerable to traffic jams.
Sameboat/Wikimedia Commons (CC BY-SA 4.0)
Smart card data are helping to unravel which stations in the London Underground system, above, may be most vulnerable to traffic jams.
Sameboat/Wikimedia Commons (CC BY-SA 4.0)