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How did miter gates improve navigation on canals near Milan?

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View of Utrecht's Oude Gracht canal lined with historic brick buildings, arched doorways at water level, and boats moored along the canal edge in the Netherlands. — canals and inland waterways The *Oudegracht* (Old Canal), Utrecht, Netherlands.

Miter gates significantly improved navigation on canals near Milan by replacing earlier vertical lift (portcullis) gates, allowing for more efficient water management and connectivity between waterways with different elevation levels.12

Key improvements included:

Enhanced Sealing: The design of the miter gate—consisting of two leaves that meet at an angle pointing upstream—creates a superior seal when closed. This minimizes water leakage, which is essential for maintaining water levels in the lock chamber.13
Interconnection of Waterways: By effectively managing water levels, these gates made it possible to link canals that were previously separated by their different elevations, such as the Martesana Canal and the Naviglio Grande.1
Technological Innovation: Often attributed to Leonardo da Vinci for his work on the San Marco Lock in Milan, the miter gate was angled to work with the downward force of the stream rather than against it, representing a major advancement over the older, more cumbersome vertical gate systems.13