Many Spans in Need of Repairs : Engineers Bridge Towering Maintenance Gap

Europe’s ancient cities built on waterways know well the hazards of depending on bridges. Some have experienced the kinds of problems New York City and other areas of the United States are now beginning to recognize.

The oldest bridges in Europe, cared for over the centuries as treasures of heritage, have fared very well--some for a thousand years. Some bridges built in Roman times in Italy still stand, virtually in their original form.

Most of Europe’s older bridges are small and not burdened by heavy traffic. But the modern spans that carry heavy trucks and cars are a constant expense and a frequent inconvenience at maintenance time.

The U.S. Federal Highway Administration said last year that of 575,607 American bridges at least 20 feet long, some 42%--or 243,646--were in need of some kind of repair. No comparable figures are available for Europe.

In New York City, the Williamsburg Bridge between Brooklyn and Manhattan, which carried some 400 subway trains and 100,000 motor vehicles a day, was found to be dangerously eroded and was closed in April, creating a massive traffic dislocation. The Williamsburg, built in 1903, has since reopened on a limited basis.

One of Western Europe’s relatively newer bridges did fall down 12 years ago. The Reichsbruecke in Vienna caved in Aug. 1, 1976, tossing a city bus and a passenger car into the Danube. But it was a Sunday morning and the bus was empty. The bus driver saved himself; the motorist died.

A 1,500-foot stretch of bridge fell, a commission said, because of a defective pier and shortcomings in its construction less than 50 years before.

In Copenhagen authorities are trying to decide whether to repair or replace the landmark Knippelsbro drawbridge, one of three links between the capital and Amager island, site of the airport and major industries.

The first wooden Knippelsbro was built in 1618, but the existing iron bridge went up in 1937, designed for 9,000 cars a day. By 1986, 40,000 vehicles and about 20,000 bicycles were crossing daily. The drawbridge opens about eight times a day with frequent breakdowns.

“I don’t like being responsible for that wreck,” said city engineer Jens Boerbach. “Something’s got to be done about it soon, because someday the bascules maybe will get stuck and then we’ll be in trouble.”

Bascules are counterweighted seesaw-like devices that make drawbridges go up and down.

Boerbach said renovation would cost $17 million. Replacement would cost $5 million more.

Stockholm, Sweden’s capital, is built on the water, and regular maintenance of its more than 100 bridges causes long detours, forcing drivers into a confusing one-way maze.

Europe’s longest bridge, the 3.7-mile Olandsbron running from Sweden’s southeast coast to the island of Oland, is about to undergo a 5-year repair project costing $10 million to $15 million.

Although only 16 years old, steel reinforcements in the bridge’s concrete pillars are corroding.

The Dutch, having wrested more than half their lowland country from the sea, have developed bridge maintenance into an art.

The 3,300-foot Moerdijk Bridge spans the Hollands Diep, a branch of the Rhine estuary, and when completed in 1936, it overcame a formidable water barrier between the northern and southern Netherlands.

But as it became a bottleneck in the Rotterdam-Antwerp highway, the Dutch managed to widen it from two to six lanes while retaining the nine original brick and concrete piers.

In 1978, its 10 steel-girded parts, each 330 feet long, were removed one by one over 10 consecutive weekends and replaced by a six-lane concrete highway resting on the old piers, which were adapted for the extra width. During the 3-month project, traffic used the bridge on weekdays.

The thrifty and resourceful Dutch even sent two of the old segments to Hoogvliet near Rotterdam to serve as a local bridge.

West Germany lost most of its bridges in World War II; 90% of the existing ones are about 30 years old.

The West German government spends about $176.5 million annually maintaining thousands of bridges on its highway system. By 1995, it expects to be spending about $470 million a year to keep the bridges in top shape, says Heinrich Poppinga of the West German Transport Ministry.

England will get $91.7 million for bridge maintenance in 1988-89, of which $38.5 million will go to 33 bridges. The pound-sterling equivalent of $8.75 million is earmarked for some of the oldest bridges, but not for London’s 25 Thames River spans, whose upkeep is financed by the capital’s boroughs.

The massive Tower Bridge, as evocative a part of London’s skyline as Big Ben, is not nearly as old as its mock-Gothic style suggests.

Opened in 1894, it is a drawbridge, raised by Victorian state-of-the-art hydraulics until 1976 when it was electrified. The stone-clad steel towers contain elevators that carry pedestrians--mostly sightseers nowadays--to high-level walkways.

The great Victorian bridge pile shrugs off serious damage when, from time to time, a wayward tidal current smashes a ship into it.

The City of London spent $7 million fixing it up in 1982. It still opens about five times a week for tall ships.

The latest London Bridge was built in 1971 after the 1831 version was shipped stone by stone to Lake Havasu City in Arizona as a tourist attraction.

Europe’s ancient bridges do not usually carry heavy traffic.

An exception is Paris’ Pont Neuf, completed in 1608, which endures thundering car traffic in the city center as one of the French capital’s 35 bridges across the River Seine.

Pont Neuf has been restored many times, but its basic construction is unchanged. All material used in repairing it and the four others classed as historic monuments is scrupulously chosen to respect its character.

No city depends more on its bridges than Italy’s Venice, built around a network of canals. The absence of cars is a help, and only one bridge, the 408-year-old Ponte delle Guglie over the Canale di Cannareggio, is undergoing some restructuring, forcing the suspension of one waterbus route.

Cement and resins are being injected into the bridge, which was showing signs of structural weakness. It was restored once before, in 1776.

The Ponte Fabricio, built in AD 62 between central Rome and Tiberina island, is entirely original. But it takes no vehicular traffic. Ponte Cestio, linking the island to the Trastevere district, was built in 46 BC and restored in 1892 with a new central arch. Its car traffic is restricted to those using the island’s hospital.

The Ponte Vecchio, crossing the Arno in Florence, was built in 1345 and underwent major structural restoration after some World War II damage and again in the 1960s, when iron bars were inserted in the pylons. It now takes only pedestrian traffic.

“They really don’t make bridges like they used to,” said Paolo Mazzoni, Florence’s environment commissioner. “If it wasn’t for the World War II blasts, there would never have been a need for structural renovation of the Ponte Vecchio.”