 Unexpected lateral vibration due to resonant structural response caused the bridge to be closed on 12 June for modifications.Attempts had been made to limit the number of people crossing the bridge, which led to long queues but were ineffective to dampen the vibrations.Closure of the bridge only two days after opening attracted public criticism as another high-profile British Millennium project that suffered an embarrassing setback, akin to how many saw the Millennium Dome.