Not just on the bridges. Several times I noticed that the ground on supposedly stable and solid areas also vibrates when buses or trucks pass by. Could be due to some underground structures (cable ducts, manholes) or the foundations of buildings (can be much wider than the actual building). It helps to stand still and feel the ground for a while, before setting up the tripod.Actually all bridges are equally bad, as the concete beams are resting on dampers. The vibrations are generated by vehicles crossing from one section of the beam to the next. Just get on to Sears Bridge and you can feel it for yourself. Small vibrations for small cars, MEGA vibrations for big trucks.![]()