Geminis are around 14ft 4in.
But when the 301 went through Dunston many many many years ago, they used Olympians and Tridents on the service and they passed under the bridge at normal speed. The only buses they had to crawl under the bridge with were the 14ft 6in Atlantean, but they still got through just save for any unlucky pigeon that would happen to get startled and get squashed between bridge and bus.
Mind had to admit I did get a fright on the Gemini when I did hear a bang which turned out to be a tree branch that the bus hit right before the bridge.
