HISTORY This Week: "How To Dig a Train Tunnel Under the Hudson River"

Air Date: February 16, 2026
Host: Sally Helm
Featured Guests:

• Jill Jones (historian, author of "Conquering Gotham: Building Penn Station and Its Tunnels")
• Polly Desjarlais (Content & Research Manager, New York Transit Museum)
• Andy Sparberg (transit historian, retired LIRR manager)

Episode Overview

This episode dives into the gripping story behind the creation of the railroad tunnels under New York’s Hudson River—one of the most ambitious infrastructure projects of its era. Host Sally Helm unpacks how Alexander Cassatt, an engineer and then-president of the mighty Pennsylvania Railroad, sought to connect his company’s trains directly into Manhattan by tunneling under the river’s notoriously tricky, muddy bed. The episode details the engineering innovations, political battles, personal costs, and ongoing legacy of what became arguably the most important train tunnels in the world.

Key Topics & Insights

1. The Challenge: Connecting the Northeast by Rail

(03:15 – 13:01)

• The Problem: As of 1900, the Pennsylvania Railroad—the world’s largest corporation—couldn’t bring its trains into Manhattan. The line stopped in New Jersey, and passengers faced an inconvenient ferry ride for the last short distance.
  • “You could see Manhattan from the end of the company’s tracks. You just couldn’t reach it.” – Sally Helm (05:29)
• Competitor Envy: The rival New York Central Railroad, owned by the Vanderbilts, had bridge access—causing deep frustration for Cassatt and his team.
  • “It was very, very galling to the Pennsylvania Railroad that their greatest rival… was the lone railroad whose passengers came in across a bridge.” – Jill Jones (12:10)

2. Alexander Cassatt: Reluctant Visionary

(08:09 – 09:08)

• Cassatt rose from surveyor's assistant to company president. He initially left due to the job's deadly stress (“the killing job”), but was persuaded to return when the company faltered.
  • “The job of president… was so demanding and so stressful that it was literally referred to as a killing job. Presidents of the Pennsylvania Railroad generally died young in office.” – Jill Jones (09:08)

3. Failed Bridge Plans & Eureka in Paris

(13:49 – 18:10)

• Initial Plan: An audacious bridge was proposed, but the $100 million price tag was too steep.
• Breakthrough Abroad: Cassatt, visiting France, is urged to see the new Gare d’Orsay station. He’s captivated by its electric trains running cleanly and quietly through tunnels—sparking the idea to tunnel under the Hudson using electricity instead of smoke-belching steam locomotives.
  • “When he saw this, I mean, he got it immediately.” – Jill Jones (17:47)

4. Tammany Hall and the Politics of Progress

(18:56 – 21:36)

• The railroad’s land acquisition for Penn Station was done secretly to avoid prices being driven up by speculators and to evade the corrupt political machine, Tammany Hall.
• When Tammany’s price ($300,000 bribe) is refused, the project is blocked, sparking public outrage. Mayor Seth Low’s direct lobbying finally tips the scales: “There is not an honest hair in the head of one of them, meaning the alderman.” – Sally Helm quoting The New York Times (20:40)

5. Engineering the Impossible: Mud, Tides, and Dangerous Work

(21:36 – 29:25)

• To manage water intrusion, engineers used compressed air to keep out the Hudson—making the work hazardous, with risk of “the bends” for sandhog laborers.
  • “When you emerged, it was like this hellish, very small space.” – Jill Jones (23:39)
• The Construction Process:
  • Workers operate at the tunnel shield, chipping away mud and rock, assembling iron lining rings, and pushing forward hydraulically—relentlessly inching toward the center from both banks.
  • “Essentially you have workers within this shield… picking away, digging, shovels, pickaxes, whatever.” – Polly Desjarlais (24:17)

6. Crisis: The Hudson Tunnels Begin to Drift

(25:39 – 30:44)

• As the two tunnel segments approach, engineers notice the tunnels “rising and falling” unpredictably.
  • “No one had ever built tunnels through goop like this so long… this was the nightmare scenario always hanging over Ray’s and Cassatt’s head: Would the tunnels be safe?” – Jill Jones (28:20)
• Attempts to fix the movement with heavier rings fail; morale is strained, and Cassatt (already ill) is sidelined.

7. Success: An Exhilarating Breakthrough

(30:44 – 31:26)

• In September 1906, the two tunnel teams meet with astonishing precision: “within 1/8 of an inch.”
  • “No computers, no digital anything. Just slide rules, steam engines and digging.” – Sally Helm (30:53)
• Celebrations erupt, but Cassatt is ill and Samuel Ray, burdened by the drifting mystery, skips the festivities.

8. The Final Puzzle: Tidal Tunnels

(32:00 – 34:13)

• Cassatt dies before completion (“the killing job strikes again”). Ray leads next steps.
• The Mystery Solved: The tunnels were moving in sync with the tidal flow—the “Hudson River” is actually an estuary. Samuel Ray’s solution? Let them flex with the tide. He keeps this a closely guarded secret.
  • “It was just absolutely kept silent.” – Jill Jones (33:59)

9. Legacy: Penn Station, Urban Growth, and Ongoing Challenges

(34:45 – 37:47)

• Penn Station, opening in 1910, transforms New York, connects the city up and down the East Coast, and ushers in the age of electric train travel.
• The original Beaux-Arts station is demolished in the 1960s; the tunnels persist and now carry over 200,000 people daily.
• Superstorm Sandy (2012) exposes the fragility of century-old infrastructure—repairing the tunnel system is now the biggest public works effort in America.
  • “The tunnels basically… still have to go into the same river, then they’ve got to get into the same station that’s still there. So it’s a project on the scale of the original project.” – Andy Sparberg (37:35)

Notable Quotes & Moments

• On the precise tunnel connection:
  “The tunnels have met within 1/8 of an inch. It's just so, so incredible.”
  — Jill Jones (30:44)

• On the importance of the tunnels today:
  “It is the lifeblood. This is a very overused term and it is a bit clichéd, but it is true that transportation powers this region. We can't do what we do without it.”
  — Polly Desjarlais (36:20)

Timeline of Major Segments

| Timestamp | Segment | |---------------|-------------| | 03:15 | Problem introduction: Hudson River as barrier, Penn RR ambitions | | 08:09 | Background on Alexander Cassatt’s rise and motivations | | 13:49 | The failed bridge plan and Cassatt’s Paris inspiration | | 18:56 | Political maneuvering and Tammany Hall | | 21:36 | Tunnel engineering challenge: compressed air and hazardous work | | 25:39 | Discovery of tunnels drifting under the river | | 30:44 | Breakthrough: Both tunnel crews meet under the river | | 32:00 | Cassatt’s death and Ray’s solution to the tidal movement | | 34:45 | Impact of the tunnels’ opening and Penn Station’s legacy | | 36:20 | Superstorm Sandy’s damage and modern rehabilitation plans |

Episode Tone

In true “HISTORY This Week” fashion, the episode strikes a balance between dramatic storytelling and deep historical insight. The narrative is brisk but rich, full of quirky period details, direct speaker quotes, and a sense of awe about technological ambition and urban change. The hosts and guests blend clear explanation with storytelling, making the material accessible and vivid even for listeners unfamiliar with railroads.

Takeaway

The Hudson River tunnels stand as a testament to American ingenuity—conceived by a man haunted by the ghosts of failed predecessors, realized through global inspiration and local grit, and continually vital long after the era that birthed them. Despite engineering triumphs and political machinations, the basic natural challenges remain: New York’s geography, human ambition, and the relentless tide.