The two-tube concrete casing that preserves Amtrak’s right of way under the Hudson Yards development and the Long Island Rail Road yards west of Pennsylvania Station in July 2014, almost a year after construction began. The photograph shows how the parallel tubes, heavily reinforced with steel rods known as rebar, were built in an excavated open cut. A concrete ceiling was later poured over the cut, making the tubes invisible from above. They make a gentle southwesterly curve between 10th and 11th Avenues, leading to West 30th Street, while descending slightly, at a 2 percent slope. Each of the tubes is about 20 feet wide, big enough to accommodate an Amtrak or New Jersey Transit train.
As part the right-of-way project, Amtrak demolished and is rebuilding the Long Island Rail Road equipment maintenance shop where the east end of the concrete casing had to be excavated. When the shop is complete, cars will roll up on elevated tracks with trenches underneath them, permitting inspectors to examine undercarriages while standing up. Flanking platforms will also make it possible to board the cars.
Excavation started predictably with Manhattan schist, the familiar bedrock that underlies much of Manhattan Island. But as crews made their way westward, they encountered a deposit of granite. “We thought that was hard,” said Dennis K. Nazzaro, a vice president of the LiRo Group, construction consultants on the project. Worse was to come: a vein of quartz that made drilling extremely difficult. Mr. Nazzaro showed samples of each.
A bridge carries 11th Avenue over the Long Island Rail Road yards where the current phase of the right-of-way excavation project is taking place. To support the bridge temporarily, Amtrak and its contractor, Tutor Perini, made use of an enormous steel beam, about 120 feet long and 8 feet tall, that had been fabricated a half-century ago for Interstate 95 in Connecticut. It was no longer needed after reconstruction work on that highway.
