How Do Tall Ships Pass Tower Bridge? The Bascules Rise

Tall ships do not pass under Tower Bridge's fixed spans. Instead, Tower Bridge is a bascule (draw)bridge: its central roadway splits into two leaves that pivot upward, clearing the full width of the River Thames for vessel passage.

How It Works

• Counterweighted Bascules: Each 1,000-ton leaf rises to ~86° in ~90 seconds, powered by hydraulic engines (originally steam, now oil/electric).
• Clearance: Open span provides ~42.5 m (139 ft) vertical clearance at high tide.
• Mast Lowering: The tallest ships (e.g., full-rigged ships) may still need to lower topmasts or topsails.

Scheduling

• Bridge lifts are pre-booked (24+ hours notice).
• ~800–1,000 lifts per year.
• Free for vessels; road traffic pauses during lifts.

Iconic Moments

Royal yachts, Tall Ships Races, the Cutty Sark (by barge), and Olympic/Paralympic flames have all passed through the raised bascules—a living symbol of London's maritime heritage.