National Geographic : 1964 Apr
Twin Barges Hold a 287-foot Tunnel Section as Tugs Pull and Push the Assembly to Sea Steel tube encased in a steel shell, the tunnel sec tion-as long as a football field and as heavy as a Navy cruiser-rode the waves from its foundry in Texas, a 2,000-mile voyage. In Norfolk, Vir ginia, the tube was fitted with a roadbed and its casing filled with concrete. Here a sighting tower rides the section's for ward end for the convenience of surveyors who use it to determine the precise location for sink ing. Lines from floating cranes maneuver the as sembly into the drop position. A sea-going concrete mixer stands by at right to add enough bulk to sink the section and fill its joints. Down into murky depths sinks the tunnel sec tion, its bed already dug by a scraping barge. Now all the skills of an anxious team come into play. Lines from cranes pull taut or go slack as a diver, trailing air bubbles, directs the awesome beaching by telephone. To avoid confusion, the painting omits the maze of lines. Diagram shows a cross section of the tunnel with its casing filled with con 608 crete and the trench covered with gravel.