Double Diamonds: New Brand for a Texas Bridge

Double diamond towers, distinctive as a cattle brand but tall as a 44 story building, have reached landmark status on the Texas Gulf Coast even though the bridge they will carry won’t be opened to traffic until 1994. The 426 ft high double diamonds are a first for a U.S. cable-stayed bridge, as are the superstructure’s dual roadways. The $91.3 million construction contract is the largest ever awarded for a single highway project in the Lone Star State. Four planes of stay cables will carry the two 78 ft wide decks that total about 350,000 sq ft, or some eight acres. Three cable-stayed spans—482-1,250-482 ft—will clear the Houston Ship Channel by 176 ft. Two side spans of 130.5 ft each bring the total length to 2,475 ft, crossing a shallow marsh on the south side and an active refinery disposal lagoon on the north. It is part of a 2.5 mi improved route that will replace the Baytown Tunnel as the direct link between the refinery centers of Baytown and LaPorte, about 20 mi east of Houston. Steel for the bridge, purchased in South Africa before the “Buy American” law was passed in Texas, was not delivered until the towers had been completed for almost a year. The towers, cast in 15 ft lifts, are each supported on dual pile clusters with a single 12 ft thick cap.