CONNECTED Steel tubed-tunnel featured industry's first big use of arc welding. Photo courtesy of Parsons Brinckerhoff

The engineering firm, now Parsons Brinckerhoff, designed the tunnel to be built by three methods: cut-and-cover work for the entrances, shield-driven tunnels from the entrances to the river and submerged tube for the half-mile river section (ENR 7/17/30 p. 111). The approach sections, about 600 ft at each end, were built similarly to subway tunnels in New York. The shield-driven sections were the first to used welded structural steel segments, instead of bolted cast iron as primary lining. The segments were chosen for their light weight, ease of construction and strength. The submerged section was built of nine steel tubes, one 220 ft long and the rest 248 ft. Their construction required 65 miles of arc welding, its first major use in tunneling history.

At 12-ft intervals, octagon-shaped dia- phragms were welded to the exteriors to serve as stiffeners and to support timber forms for concrete jackets. A trench was dredged in the river bed and lined with sand. The tubes were towed to a nearby slip where the interior concrete lining and floor slab were cast. Sited over the trench, tremie concrete was poured and huge concrete blocks placed on top to sink it. The concrete made joints between adjacent tube sections water tight.

The tunnel's ventilation scheme was borrowed from the new Holland Tunnel in New York. The Detroit-Windsor link was built in 29 months, unprecedented speed in those days, and opened on Nov. 1, 1930.

1931
Empire State Stands Tallest for Decades

RISING Floors went in fast. Courtesy of Parsons Brinckerhoff

The Empire State Building stood as the world's tallest building between 1931 and 1972, but it started out as a 50-story, 650-ft-high office building when first announced in 1929. The New York City landmark went through 16 designs by architects Shreve, Lamb & Harmon before it ended up as an 86-story, 1,250-ft tower.

At the beginning of the Great Depression, there was a three-way skyscraper race under way in Manhattan. The Bank of Manhattan Building raised its building height from 840 ft to 925 ft. Walter Chrysler raised the height of the Chrysler Building from 808 ft to 1,048 ft by adding a stainless steel spire. John J. Raskob, the main force behind the Empire State Building, added five stories to raise it to 1,050 ft. Later, to reinforce his lead, Raskob added a 200-ft tower that would serve as a mooring mast for dirigibles. This function never was seriously considered by any dirigible operator but it gave him a height of 1,250 ft.

For structural engineer H. G. Balcom and Associates, the main challenge was designing the steel frame to meet wind loads. The building is supported by 210 columns with a maximum cross section of 640 sq in. Nearly all columns are braced in each direction on the center line and deep knee braces at service areas are concentrated in the core of the building. For wind bracing, a design pressure of 20 psf was used above the sixth floor and 30 psf above the 86th floor.

After demolition of the original Waldorf-Astoria Hotel, which had occupied the site, general excavation began on Jan. 22, 1930, with construction getting under way two months later. Building completion, set for May 1, 1931, was achieved a few weeks early. Construction was elaborately programmed by Andrew J. Eken, chief engineer of the general contractor, Starrett Bros. & Eken Inc. The building's 58,000 tons of structural steel were put in place in six months at the rate of 4.5 floors per week.

Steel and other construction materials arrived by trucks that drove into the ground floor and were moved to a railway system on each floor. Expediters at the materials' sources arranged for delivery to coincide with installation (ENR 8/21/30 p. 280). The work force, which averaged 2,500, peaked at 4,000. Contrary to folklore of the time that skyscrapers cost a life for every floor, there were only five deaths during construction of the Empire State Building.

The record-setting building was planned during the Roaring Twenties and estimated to cost $43 million. Built with Great Depression dollars, it cost only $24.7 million. But hard times left the structure with so few tenants that it was called the Empty State Building. Not until 1944 did it reach 85% occupancy.