The barriers are built at the three entrances along the coast where the sea enters the lagoon:
- 2 at Lido (21 + 20 bulkheads) given the width of this port entrance and the two canals of different depths
- 1 at Malamocco (19 bulkheads)
- 1 at Chioggia (18 bulkheads).
When the bulkheads are inactive they remain full of water and completely invisible in their housings on the bottom of the entrance canals.
When there are high tides, compressed air is injected into the bulkheads to empty out the water, and as it gradually empties (it takes 30 minutes in all), the bulkheads rotate around their hinge axis and rise out of the water and block the sea flow into the lagoon.
When the tide goes out, the bulkheads are filled with water again and return into their seats (in 15 minutes) and do not affect the exchange of water between the sea and lagoon.
The Mose guarantees complete defence of the land against flooding, it does not alter the water exchange at the port entrances (it does not alter the depth or previous sections of the entrance canals), and it does not interfere with the economic activities that pass through the mouths:
- At the Malamocco mouth a navigation basin has been constructed for large ships (shown in the photograph) that allows the port to continue working even when the bulkheads are in action.
- The other navigation basins (2 in Chioggia and 1 in Lido – Treporti) allow the fishing boats and pleasure craft to pass through even when the bulkheads are active.
The Mose System costs a total of 5,493 million euros, so far 5,267 million have been funded and a further 226 million are needed.
An estimated 4.000 people are involved in the construction of the Mose and around 1000 of these are working in the port entrance sites.