Navigation lock for 150,000 DWT ships at the inlet of Malamocco in the Venice lagoon (Italy)

The navigation lock is 371 metres long and 50 metres wide and 13,5 metres deep at mean water level and is equipped with two sliding doors lightened by a special water jet system and manoeuvred by cables. No steel rails have been used since sliding of the lighten doors (no more than 50 t) can be done by Teflon strip.

Each lateral wall of the lock chamber is built with two alignment of a combined wall steel structures: a sequence of 1.4 metres diameter steel piles and two element of sheet piles. The two alignment are connected by tension rods at a distance of 2.67 metres located at +1.0 metres. Piles are 37 metres long and are driven in the soil.

A detailed analysis has been carried out to demonstrate that a concrete bottom slab is not needed and that the lock bottom can be built only by a sequence of granular material with different grain size.

No pumps are needed to modify the water level in the lock since the water level sea side is always higher than the water level land size. Water level variation in the lock is obtained by manoeuvring ten stop log located directly on the doors. The operation is carried on in less than 30 minutes.

The lock is equipped with two guiding walls. The entrance areas where ships can use their propeller to change speed and direction is protected by 1.3 ton layer of stones.

The contract included the provision of the following services:

• Detailed Design of the structures and of the equipment 
• Bill of Quantities and Cost Estimate
• Tender Documents
• Mathematical model study of the hydrogeology around the lock to define the bottom characteristics
• Meological - geotechnical investigation and analysis to support the design;
• Maintenance and Operation Manual