“That’s a myth,” Lucas said, politely but firmly.”That’s definitely a myth.”
~Peter Hartlaub, San Francisco Chronicle
Legend holds that the cranes of the Port of Oakland were the inspiration for the AT-AT walkers in Star wars. These structures have since turned into a symbol for Oakland and are frequently sported on t-shirts. I went there to have a look myself, made some drawings, listened to people and spice it all up with what George Lucas had to say on the matter (not to me, though).
VISUAL FLANEUR - drawing life on the streets 
So they weren’t consciously modelled on the cranes, but damn they do look very similar. Wouldn’t be surprised if there were some subliminal influences at work…
Yes, possible. The subconscious is always an option…