South Korean train passengers no longer need risk the embarrassment of mistakenly implying a woman is pregnant. A pilot program uses wireless sensors to trigger a light when a pregnant woman approaches a seat.

The ‘Pink Light’ program in Busan involves the women carrying a small beacon that runs for six months on a single battery. Whenever the beacon comes close to a priority seat (one nearest the doorway) a small sign beside the seat lights up.

The program is designed to achieve several goals. One is to deal with the way it’s not always obvious if a woman is pregnant and in greater need of a seat, along with the potential embarrassment of offering a seat to a woman who is not pregnant.

Another is to save time when a pregnant woman gets onto a crowded carriage and a person sitting in a priority seat can’t immediately see her. There’s also some social pressure as the light will make it clear to everyone that the person in the seat is well aware somebody else needs it more than they do.

The program had a successful pilot on one train line and officials plan to extend it to the city’s entire bus and rail network.