The only time a bridge tender didn't answer on the vhf was when he didn't have a visual on me. It seemed to me that many just don't ansewr unless they can see you. A kind of 'if I can't see you your too far away to care about so why respond'.

I also had the thought that the bridge's vhf had a range of about 1/2 mile just to block out the chatter from more distant signals. They also don't seem to respond if it's not close to a scheduled opening.

Was the non response on the vhf when you were close to the bridge and an easy visual?