It’s one thing to build a road across the land and another to build a bridge over a waterway, but it’s totally another project to build a tunnel under the water. The first such tunnel in the world was completed in 1843 after almost 20 years of work, and was built under the River Thames in London, connecting the East End of London to Rotherhithe. Since then, many of these “underwater roads” have been constructed. Most long-haul truckers, at some point, have more than likely traveled through one or more of these engineering marvels, but for some folks, these tunnels are less known.
In 1818, a French engineer named Marc Brunel invented a device that would enable workers to tunnel under rivers without having the mud and water ruin their efforts. His “tunnel shield” was a rectangular device that had cast iron walls with dozens of small shutters, and workers would open the shutters one at a time and dig out a few inches of dirt. Screw jacks would push the whole shield forward, and as the shield lurched ahead, inches at a time, workers behind it constructed a thick brick lining that became the shell of the tunnel. The 1,300-foot long passage below the Thames River, built for carriages and pedestrians, took 18 years to complete and was 35 feet wide, 20 feet high, and ran 75 feet below the river’s surface.
Engineers around the world began adopting the idea Brunel was knighted for. Some of the greatest underwater passages, including New York’s Holland and Lincoln tunnels, were created with variations of the tunnel shield. Air-tight seals were used to keep the air pressure as high as possible under the river to counter the intense pressure above the tunnels during construction, which often caused flooding and structural collapses. There were many advantages to these underwater roadways, including use in any weather, a smaller footprint of entry (compared to bridges), and unrestricted water shipping above the tunnel.
In 1920, funds were appropriated and construction began on what was referred to at the time as the Hudson River Vehicular Tunnel (now known as the Holland Tunnel). Opening in 1927, the tunnel operated under the guise of two state commissions until the Port Authority of New York and New Jersey took over in 1930. The tunnel crosses under the Hudson River and connects Canal Street in Manhattan with 12th and 14th Streets in Jersey City, NJ, and is considered to be an outstanding engineering achievement. The tunnel bears the name of the first chief engineer, Clifford M. Holland. Holland and his team overcame many engineering issues when designing this tunnel.
With the dawn of the automobile age came the significant challenge of ventilating the 1.6-mile long tunnel and figuring out how to safely remove the car’s dangerous exhaust fumes from the enclosed space. The 3rd chief engineer, named Ole Singstad, came up with the solution by designing four ventilation buildings (see photo), two on each side of the river, which were five stories tall and housed 84 huge fans that provided a change of air every 90 seconds in the tunnel, keeping the air quality inside well within established safety limits.
This innovation made the Holland Tunnel the first mechanically ventilated vehicular tunnel, as well as the first vehicular crossing of the Hudson River. Over the years, many other underwater tunnels were built using the construction techniques used on the Holland Tunnel. In 1993 the tunnel was designated a National Historic Landmark by the US Department of Interior.
After the success of the Holland Tunnel, the New Deal’s Public Works Administration provided funds in 1934 to begin construction of the Midtown Hudson Tunnel, which opened in 1937. The tunnel connected Weehawken, NJ to Midtown Manhattan, and was hailed as the next great engineering triumph. A second tube was built shortly after the first, with a third being built in the late 1950’s, due to increased traffic. The tunnel was eventually named the Lincoln Tunnel after President Abraham Lincoln, because the Port Authority believed the tunnel was “parallel to the importance of the George Washington Bridge” which was opened in 1931 and had been named after President Washington.
The Baltimore Harbor Tunnel stretches from the south shore of the Patapsco River to the north shore near Dundalk. The first section of the tunnel, which is 1.45 miles long, was sunk on April 11, 1956. The tunnel, and most of the I-895 Thruway, opened in 1957, nearly two months ahead of schedule. There were twenty-one 310’ sections, and each was individually submerged into the harbor and then secured with rocks and backfill.
Before the Chesapeake Bay Bridge-Tunnel was built, 50-60 cars would drive onto ferries that carried them across the water, with the Atlantic Ocean to the east and Chesapeake Bay to the west. Construction of the Bridge-Tunnel started in 1960, and when it was completed and opened in 1964, the American Society of Civil Engineers named it one of the seven engineering wonders of the modern world.
In its entirety, the Chesapeake Bay Bridge-Tunnel crossing is about 23 miles long, and includes more than 12 miles of trestle bridging, (2) 1-mile long tunnels, (4) artificial islands, (4) high-level bridges, two miles of causeway, and more than six miles of approach roads. The two tunnels, which dive underwater in the middle of the Bay, allow ships and boats to safely and easily pass over them. The tunnels are connected to the bridge by the four man-made islands, that are each as large as a football field.
To construct the tunnels, workers dug huge underwater ditches and lined them with rocks, then they lowered plugged-up pieces of the concrete tunnel into the ditches. After connecting all the pieces, they were unplugged to allow vehicles to travel through them. When it first opened in 1964, there was only one lane northbound and southbound, until 1999, when one more lane was added in each direction.
I remember going south on my way to Norfolk, VA once and as I was going down into the tunnel there was a ship crossing at the same time. I wish I had that picture! Thinking about that ship and all that water and weight above me was a little scary, but I made it!!
The George C. Wallace Tunnel goes under the Mobile River in Mobile, Alabama on I-10. Sections were made at the shipyards of the Alabama Dry Dock and Shipbuilding Company. After the sections were built, they were then floated into the proper position and sunk. As each section was sunk next to the previous one, they were joined together underwater. After all the sections were connected and concrete was set in place, the tubes were pumped out and finished inside. The tunnel opened in 1973.
Planning began in 1982 for the “Big Dig” in Boston – a megaproject that consisted of several projects to re-route I-93 through several tunnels and bridges, to help alleviate the horrendous traffic in Boston. At the time, rush hour lasted 10 hours a day, and the accident rate was four times the national average – and it was just getting worse. One part of this project, the Ted Williams Tunnel (TWT), named for the Boston Red Sox legend, actually opened on time December 15, 1995 and within the 1.3-billion-dollar budget. The TWT runs beneath Boston Harbor and created a new access road to Logan International Airport, saving motorists as much as 45 minutes (see photo of truck driving through tunnel). The .75-mile underwater part of the 1.6-mile tunnel used 12 steel tubes, each longer than a football field, placed in a trench, then connected.
I’m sure that the people who built those first tunnels could never have imagined the traffic that we would have today and just how important this means of getting from one shore to the other would become. And who would have thought that the first automobile traffic would cross under the Hudson River and not over it! As bad as the traffic is just about everywhere these days, think of how much worse it could be if these pioneering engineers did not have the vision and intelligence to make these amazing underwater roads.