Transactions of the American Society of Civil Engineers, vol. LXVIII, Sept. 1910

In the heart of early‑20th‑century Manhattan, engineers embarked on a bold expansion of the Pennsylvania Railroad’s terminal, carving a new tunnel through a six‑acre block bounded by Ninth and Tenth Avenues. The project began by clearing a dense urban fabric—nearly a hundred houses, apartments, and even a church—many of which were purchased outright while others required delicate condemnation agreements. The displaced congregation of St. Michael’s secured a fresh site and a brand‑new complex, illustrating how civic development and community needs intersected in this massive undertaking.

Behind the demolition, a staggering amount of earth‑moving and rock‑cutting unfolded around the clock. Contractors excavated over half a million cubic yards of mostly gneiss, laid tens of thousands of cubic yards of concrete, and installed a mile‑plus of structural steel, all while managing the disposal of spoil via a purpose‑built trestle to the Hudson River. Detailed accounts of the geology, from quartz veins to glacial markings, reveal the scientific rigor that guided the engineers as they reshaped the city’s underground landscape.