In our throw-away American culture, where $55 million structures such as Three Rivers Stadium stand for 30 years and are destroyed even before the drab doughnut's remaining $18 million debt is paid off, it's worth noting that seven miles of train tunnels drilled under two rivers more than a century ago still carry passengers in and out of New York City every day.
"All of the tracks and the tunnels coming in and out of Penn Station that were built by the Pennsylvania Railroad in the 1900s are still there and still working," said Randall MacLowry, the writer, producer and director of "The Rise and Fall of Penn Station."
That is just one of the astonishing facts viewers learn from the one-hour "American Experience" documentary that WQED airs at 9 p.m. Tuesday. A grand public space that was also a monument to engineering and vision, the original Penn Station occupied four contiguous blocks.
When it opened in 1910, it was the fourth largest building in the world and had been constructed without any public tax dollars. It was built after Alexander Cassatt, who became president of the Pennsylvania Railroad in 1899, realized that his company's trains stopped one mile short of New York City and that passengers had to board a ferry to reach Manhattan.
While visiting Paris and his younger sister, Impressionist painter Mary Cassatt, the railroad executive spent three days looking at a new station called the Gare d'Orsay where trains passed through tunnels on electrified tracks.
Samuel Rea, head engineer on Penn Station, never went to college and later ran the Pennsylvania Railroad. Rea had urged Cassatt to visit the Paris train station. In 1902, Cassatt hired architect Charles McKim, designer of the Boston Public Library, to draw up plans for Penn Station.
Once drilling began for the $50 million project, one New York newspaper called it, "our own Panama Canal here on the West Side of Manhattan." A total of 16 miles of tunnels were built, seven of which were under water. The tunnels had to support trains that weighed several tons and traveled at high rates of speed.
To connect New York with New Jersey, shafts were drilled in Manhattan and Weehawken, N.J., and two tunnels built under the Hudson River. Another four tunnels built under the East River connected New York and the Pennsylvania Railroad with the Long Island Railroad. The third phase of the project, completed in 1917, was the opening of the Hell Gate Bridge, which links New York to New England.
The Hudson River's soft, silty underbelly presented challenges. To build the tunnels, workers known as "sandhogs" used what was called a Greathead Shield. It was based on a design by James Henry Greathead, an English civil engineer who also worked on the London Underground railway.
"The shield is a huge iron cylinder inside which the tunnel gets built. At the front of the cylinder is a cutting edge," Mr. MacLowry said, adding that the shield weighed 200 tons, was 23 feet in diameter and 17 feet long.
"At the front of the shield, there were nine compartments," Mr. MacLowry said. "They could open them up and all the soil and rock would flow through. Or, they would go into the front of the shield and shovel the muck into waiting carts that got taken out through the rail tracks inside the tunnel."
Similar technology was used to build London's Underground.
"If you had rocks or bedrock in front of you, you would have to blast the bedrock. In the back of the shield, they had these very strong pneumatic jacks. That's what pushed the tunnel forward," Mr. MacLowry said.
Within the tunnel, sandhogs inched along, bolting together a series of 21/2-foot-wide iron rings, each made up of 12 segments. They would build a ring and push forward, Mr. MacLowry said, adding that it was like pushing a can through sand. Then, the rings were covered in concrete.
The deeper they drilled, the greater the water pressure. To keep back the soil, workers used compressed air. They also had to keep water out of the tunnel to prevent death by drowning. Compressed air could be deadly if workers did not progress properly through air lock chambers. Some workers drowned while others suffered bad cases of "the bends."
By 1961, the Pennsylvania Railroad was broke and Penn Station was dirty. The railroad sold the building, and demolition of Charles McKim's architectural masterpiece began in 1963.
Before destruction began, a group of architects protested; one of them carried a sign that said, "Polish It, Don't Demolish It."
Today, the site holds Madison Square Garden and an office complex called Penn Plaza.
"The current Penn Station," Mr. MacLowry said, "has a lot of detractors. The station itself is all underground. The original Penn Station harked back to these great public spaces of ancient Rome. ... It still stuns me. I would loved to have gone inside the main waiting room."
Marylynne Pitz: firstname.lastname@example.org or 412-263-1648.