Cat paver plays key role in safeguarding Venice

Issue: August/September 2008

For centuries Venetians had given in to the Adriatic Sea, learning to meet its unique challenges rather than trying to hold back its tides. Today, Venice remains relatively unchanged. With its centuries-old influence on art, music, architecture and literature, and as the 13th century home to famed explorer Marco Polo, it’s one of the world’s most popular tourist destinations – a destination that many people call a ‘floating museum’.

Venice was built on an archipelago of 118 islands, with over 150 canals and over 400 bridges connecting the islands. Visitors and residents to the old lagoon city travel only by water or on foot. The city is considered Europe’s largest car-free urban area. So why would a city like Venice need a state-of-the-art Cat® AP655D asphalt paver? To help safeguard this historic city for the 20 million visitors who navigate its waterways each year.

In 1966, a major flood caused incalculable damage to the city. Venice and nearby towns and villages were submerged under more than a metre of seawater. The pumping of groundwater and methane gas to meet the region’s industrial needs likely caused Venice to begin to sink. Nearly 28 cm have been lost in just the last century. Although the pumping practices have long since ended, their effects, combined with today’s rising sea levels (widely attributed to climate change) have caused more frequent high-tide events.

Today, Venice experiences high tide events with a frequency eight times more than in the early 1900s. Flood tides especially threaten the city throughout the winter months and ground floor structures are no longer habitable throughout the city.

Safeguarding Venice is delegated to the state and is carried out by the Ministry of Infrastructure - Venice Water Authority, through a consortium of Italian engineering and construction companies. In 2003, the consortium (Consorzio Venezia Nuova) began what is regarded as the largest public works project in Italian history. Called Modulo Sperimentale Elettromeccanico or Electromechanical Experimental Module (MoSE for short), the project intends to further defend Venice with a system of 78 inflatable mobile flood barriers that will separate the city from the Adriatic Sea during exceptional high-tide events.

The flood barriers will be completely invisible and will remain in their underwater housing on the floor of their inlet canals, until needed. Compressed air will empty water to raise the gates, blocking incoming seawater. The MoSE system has been conservatively designed to allow for a global sea level rise of up to 60 cm, twice as high as worst-case scenarios currently estimated by scientists. Three separate inlet gate locations will be constructed. When combined with 45 km of defenses previously installed along the coastline, these gates will allow even greater flexibility and control.

Temporary construction platforms - man made areas - are in the works at each of the inlet sites. They minimise land use, enable the transportation of equipment and materials by sea, allow for dry storage, and facilitate construction and launching of the structural elements (caissons) for each row of gates.

One such temporary prefabrication is currently under construction for the gates at Malamocco and Lido San Nicoló. A new Cat® AP655D with steel track undercarriage, one of the largest asphalt pavers in the Caterpillar® paver line, is helping to pave each of its 18 plots, 13 hectare (130,000 square metres) in total. Each prefabricated plot needs to be capable of supporting the weight of the concrete structures, some 25 m long and 15 m high.

“To ensure correct construction of these large concrete elements, and avoid possible differential settlements at their base during construction, it was essential for the support surfaces of the structures to be exceptionally sound and comply with extremely precise levelling tolerances,” Enrico Pellegrini, site manager of Grandi Lavori FINCOSIT SpA, said.

“This is why we decided to use the new Cat AP655D paver for construction of the lean concrete binding layer, with a thickness of approximately 8 cm.”

http://www.roadconstruct.com.au/Article/Standards-of-road-construction-machinery-to-rise/430619.aspx

Standards of road construction machinery to rise

12 November 2008

THE ASSOCIATION of Equipment Manufacturers (AEM) and SAE International have agreed to provide funding assistance to the road construction sector.

The agreement involves a resolve to take a more comprehensive approach to standards-development in the off-road equipment industry.

The partnership with SAE transfers financial costs from individual companies to AEM on behalf of the industry, and continues the support of important industry-related standards work.

The association says the partnership will provide long term value to manufacturers and all industry stakeholders by providing more clearly defined US standards.

http://www.equipmentworld.com/categories.aspx?z=681