I wasn't criticising anyone, I was 1) asking if that happened; 2) asking why it might not have.

I think the answer is much more likely that the loss of power disabled the horn (as others have suggested) than that the crew thought it wasn't worthwhile because there was insufficient time for anyone on the bridge to fare any better anyway!

Hard to blow your electrically driven horn when you've lost power.

Even so, it probably still requires electricity to activate the solenoids to open the valves or whatever. I'm speculating since I don't know how large boat horns work, but I wouldn't be surprised if they require power.

Also, how does the driver know what to do? Stopping on the bridge, even well before the point where the ship hit, was clearly the wrong choice. Authorities need to stop new cars from entering the bridge while those on it leave, but that takes more than a handful of seconds to arrange. Unless there are traffic lights, perhaps.

It's hard for people on the bridge to understand what that means. The more it blasts the horn, the more likely people to turn around, stop and maybe get their phones out to take a video what strange thing this ship is doing. By the time they realize the impact is imminent, it's too late, unless they take a helicopter ride.