THINKING BIG : Feats of Clay . . . and Stone and Steel : Bridges

In 1874, the safety of the first bridge across the Mississippi River at St. Louis was tested by shuttling progressively heavier trains across it while engineers took measurements. But an elephant from a local zoo provided the crucial public test. It mounted the approach without hesitation and lumbered placidly across, drawing cheers from a crowd convinced that an elephant wouldn’t set foot on an unsound bridge.

* The London Bridge was sold to the McCulloch Oil Corp. of Los Angeles for $2,469,600 in 1968. The 11,800 tons of facade stonework were reassembled at a cost of $7.2 million at Lake Havasu City, Ariz., and rededicated in 1971.

Aqueducts and Canals

* The world’s longest modern aqueduct is the California State Water Project aqueduct, completed in 1974. It measures 826 miles.

* The longest canal in the ancient world, at 1,107 miles, was the Grand Canal of China from Beijing to Hangzhou. It was built from 540 BC to AD 1327 with a work force that reached 5 million.

Roads and Rails

* The Pan-American Highway-- which runs from Alaska to Chile, then to Argentina and Brazil--is more than 15,000 miles long.

* The most extensive underground or rapid-transit railway system among the 94 in the world is the London Underground, with 254 miles of route. In 1991-92, it had 273 stations and 570 trains, and it carried 751 million passengers.

Miscellaneous

* The largest trilithons are in Britain, at Stonehenge, near Salisbury Plain, with single sarsen blocks weighing more than 50 tons. The start of

construction has been dated to 2800 BC. Scholars continue to debate whether it was built as a place of worship, a lunar calendar or an eclipse predictor.

* The World Trade Center in New York has 43,600 windows. They are cleaned automatically by machines traveling along stainless steel tracks.

* Shell Oil’s new Auger platform in the Gulf of Mexico is 3,280 feet high--more than twice the height of the world’s tallest building.

Sources: Science and Technology Desk Reference; Timetables of Science; Guinness Book of World Records, 1994; American Society of Civil Engineers

Compiled by Times researcher JANET LUNDBLAD