The ice must be pretty thick, because those are some pretty good size bomb.
It's not the THICK ice causing problems, in fact, icing river surface when thick enough, can became a commuting route on its own. It's those semi-melt, melting-and-icing-on-the-go kind of floating icebergs causing trouble to commuting coveys, and serious damage to river banks happen to be on their way, and the people whom happen to be living on those banks.
To tell how powerful those floating icebergs is - they can re-shape the riverway, they can bury whole village overnight, until as recent as Chinese people have had flying bombers (and master the use of them), local governments across
all dynasty, put militia overwatch posts along the upriver of the whole yellow river, and emperors demands daily updates (by overnight express military post services), during winter-spring era each year when ice start to melt. It's a yearly disaster and took lives yearly.