I have posted here before about my BC cross barking like a maniac during his
walks.

History....

Had two dogs, Airedale and BC cross. Airedale passed away about a month and
a half ago now. Since then, BC has taken to barking non stop on walks. Still
walks nicely with a loose lead etc... but barks almost the whole time.
Finally quiets down as we are returning up the driveway to end the walk.
People look at us and cross to the other side of the street, thinking he's a
crazy dog. :-)

I have tried getting him to carry something in his mouth.... works for two
seconds, then keeps dropping it to bark.
I have tried the "quiet" command, which works 100% in the house and in our
own yard. He doesn't even acknowledge I have said anything.
I have tried stopping as soon as he starts barking and making him sit until
he quiets and then continuing on the walk. He doesn't get it. For three
days, we never made it out of the driveway.
Tried a muzzle..... nevermind, just barked slightly smaller barks.
Even tried a bark collar..... barked and yelped through the stupid thing.
Tried a water bottle..... no joy.

This is an almost perfect dog in all other situations. Very well behaved and
obedient except while walking.
He follows basic commands, except "quiet" the whole time while barking
crazily.
I don't know what else to try.
Any suggestions? My neighbors are getting annoyed and I don't want to stop
walking him, he needs his exercise, he is a BC.

Thanks in advance for any suggestions.