To happen to pass by; to go past without stopping. Similar to '通り掛かる' but with a stronger sense of passing by.
駅前を通りすがるだけだったが、偶然古い友人に会った。
I was only passing by the station, but I unexpectedly met an old friend.
彼は店の前を通りすがったときにウィンドウのディスプレイを見た。
When he passed by the shop, he looked at the window display.
散歩中に通りすがる人々の服装を見るのが好きだ。
I like looking at the clothes of people I pass by while walking.
通りすがる犬が急に吠え出して驚いた。
A dog passing by suddenly started barking and I was startled.