The waterway is a landmark of the glittering South Korean capital, but also a frequent scene of despair in a country with one of the world's highest suicide rates.
The artificial intelligence-driven surveillance system alerts first responders if someone lingers in certain locations, enters an area deemed unsafe or picks up one of the bridges' dedicated suicide-prevention phones.
It has been strikingly effective, said Kim Jun-young, chief of the Hangang Bridge CCTV Integrated Control Center, with the rescue rate over the river rising to more than 99% from 56% in 2012.
Emergency crews can reach most bridges within five minutes -- the critical window to intervene and save a life, he said.
"We see our role as giving them one more chance to think it over, because it may not be the decision you want," Kim told AFP.
