Canadian Consulting Engineer

Venice

"Ah, Venice!" said our hosts with emphatic excitement, "You must go." So we went.The train crosses the causeway, sea lapping on either side. Venice emerges from the mist, like a mirage suspended betwe...

October 1, 1999  By Rosalind Cairncross, P.Eng.

“Ah, Venice!” said our hosts with emphatic excitement, “You must go.” So we went.

The train crosses the causeway, sea lapping on either side. Venice emerges from the mist, like a mirage suspended between sea and sky. Writers, poets and artists of every kind have exhausted the supply of superlatives singing the praises of the city of light and art and architecture, of commerce, political intrigue and a thousand interesting things. Relatively unsung are the feats of engineering upon which the whole incredible city literally rests.

A collection of muddy islands in the middle of a lagoon seems a less than ideal location for a settlement. Unless, that is, the people who hold the dry ground won’t leave you in peace. In the fifth century the crumbling Roman Empire was under attack by successive waves of “barbarians” who swept through northern Italy on their way to Rome. The residents of the region, some of them Roman, fled to the islands for safety. Never shy of an engineering challenge, they set about turning their destination into home. Venice is spread over 117 small islands connected by an elaborate tracery of canals.

For the early settlers the first task was finding firm foundations which could stand the wash of the tide and the shifting silt of the lagoon. The unstable soil of the islands could not support the weight of buildings. The legendary pilings of Venice were their solution. The city rests upon a forest of logs driven into the earth, covered with a platform of thick planks.

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This unlikely structure supports buildings ranging from simple row houses to huge palaces, cathedrals and public buildings. Documentation from 1663 describes the process of laying the foundations for the church of S. Maria della Salute: “Construction was begun by driving into the subsoil one million, one hundred and six thousand, six hundred and fifty-seven piles of oak, alder and larch, each about four meters long. This preparatory phase took about two years and two months to complete. Then a platform like a huge raft made of planks of oak and larch firmly lashed together was built on this base of piles.”

Judging by the evidence of their work from hundreds of years later, the planners and builders thought carefully and well. Their watery world on the fringe of the Adriatic Sea produced a unique society with structures which tried to turn difficulty into advantage.

Architects and builders were acutely aware of the nature of the foundations upon which they built. Ever conscious of the weight of their buildings, they sought to lighten the load whenever possible by using bricks instead of stone, incorporating many windows and arches in their design. The elegant openings of the palaces which line the Grand Canal are proof that aesthetic considerations did not take a back seat to practical ones.

All the practical problems posed by living on this tiny piece of real estate do not, however, lend themselves to easy solutions. Designing light and airy rooms for important buildings is not especially difficult. Designing light, airy streets in a city with buildings packed closely together is a different matter. The city is riddled with dark alleys and gloomy staircases.

Civil works in the city-on-pilings present numerous challenges. Water is one of these, a very important one. The bond between the city and its water is captured by the inscription by the Magistrato alle Acque of 1553: “Venice, founded at God’s command among the waves, surrounded by water, protected by walls of water. Whoever dares to despoil this asset of the community shall be no less severely punished than he who damages the walls of his native city. This edict shall stand for all time.”

The walls of water which protect the city also damage it with regular floods. Regulations dating back to the 1500s and earlier abound. They control embankments, the building line, and keep the waters of the canals clean and clear of silt. Living in water requires the building of bridges and paved paths, courtyards and boats. At the height of her powers, Venice had a boatyard employing 16,000 workers turning out a boat a day. If the civil engineers didn’t have enough to do dealing with the waters of the lagoon, there was always the problem of drinking water to keep them occupied.

As Marin Sanudo commented in 1880, the city “which is situated in water has no water.” Drinking water for its 100,000 residents was supplied by wells — 6,782 well heads existed in 1858 — in the streets, squares and courtyards. Keeping freshwater fresh when you are in the middle of a lagoon also needs planning and regulation to keep sea water at bay.

The light meets the water on the Grand Canal, “the most beautiful street that exists … in the whole world,” wrote Commynes in 1494. That was true then, and it may be so now. It is harder to tell when the Canal is heaving with boatloads of tourists, shoppers, workers, supplies, garbage, with water taxis, ambulance and police patrol boats. The shimmering reflection of the light on the extravagant buildings, the rippling reflection of the buildings in the water, the extraordinary concentration of art and architecture, are what made this fabulous (in the original sense of the word) city famous. It owed its riches to the fortunate accident of its location between Europe and Byzantium before the days of the sea route to the Far East, to the skill of its seamen, to war, to trade and to shrewd political manoeuvering. The fiery horses which paw the facade of St. Mark’s Basilica were the symbol of Venetians’ pride in their independent city state. For 1,000 years they jealously guarded that independence in the face of threats from land and sea, until at the end of the 18th century the 120th Doge handed over power to Napoleon.

Now Venice is once more under threat. This time the enemy is faceless and diffuse: the city is under attack by the industrial technology of the 20th century. Venice is crumbling, sinking and shrinking. Neither the Doge’s horses nor his men could have foreseen this threat.

For the modern Venetian, living in an open air museum is a mixed blessing. Employment opportunities are limited, the cost of living is high. The population numbers 8,000 and is shrinking. In the last 40 years one third of the inhabitants have moved to the mainland. During the season, tourists double the population, crowding the city, driving up prices. The tourists do, however, bring the funds which are badly needed for restoration.

The city has been wrestling with its problems, but the solutions are not simple. Its plan to expand employment opportunities, for example, had some unexpected consequences. It proposed developing an industrial complex, to be built in three stages, on the mainland two miles away. The first two stages produced enough damage to the city to halt the plan. Sulphur dioxide from the industrial complex started to erode the numerous statues, statues which had remained untouched for hundreds of years. Today, scrubbers control emissions to limit the damage. And home heating oil, also a contributor of sulphur dioxide, has been changed to methane.

The industrial complex also contributed to the sinking of Venice. The factories drew water from the underground source which served the city, depleting the reservoir. The weight of the buildings above the resulting gap caused the city to sink by 10 centimetres before a solution was found. Water is now supplied to the city from the mainland, but the precious 10 centimetres appear to be lost forever. The sinking produces another problem — increased flooding into the lagoon. The lagoon is diked off for other activities such as fish farming and is therefore smaller than it once was, compounding the flooding. The proposed solution is to install large gates at the three entry points to the lagoon. The measure may control flooding, but may also hinder the flushing of the lagoon. Having experienced the unintended effects of other solutions to Venice’s problems, not everyone is enthusiastic about this one.

If the ancient city is a tribute to the planners, engineers and architects of centuries long past, it i
s a major challenge to their counterparts today. So far modern efforts have produced no durable solutions. They have, however, produced enough unintended extremely damaging consequences to make planners aware that any new measures demand great caution and awareness of the complex elements that support the city.

Watching the city ripple in the low evening light, it is not difficult to conjure up the image of a galleon or two on the horizon — just the way things were in the city’s heyday. But modern Venetians are not museum figures. They need modern amenities. Venice must find a way in which to provide those while preserving her historic splendour. CCE

Rosalind Cairncross, P.Eng. is a contributing editor of CCE magazine.

References: The Art of Renaissance Venice, Norbert Huse & Wolfgang Wolters. University of Chicago Press, 1990.

Venice: Gondola’s and Groceries. Filmwest Associations, Kelowna, B.C.

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