Including the tunnel and approach roadways, the facility is approximately The tunnel was formed out of twenty-one foot-long 94 m sections individually submerged into the harbor and secured with rocks and backfill; the first of these tunnel segments was sunk on April 11, In addition, vehicles in excess of 13 feet, 6 inches, in height, or 96 inches 8 feet in width; and all double trailers are prohibited from using the Baltimore Harbor Tunnel.
Vehicles carrying Class 1 explosives and radioactive materials require an escort at the Francis Scott Key Bridge. Water depth in the harbor varies considerably, and can range from under 10 feet to more than 40 feet deep, according to NOAA. To use this method, builders dig a trench in the riverbed or ocean floor. Once the trench was prepared, workers aboard a screed barge which looks like a truss bridge section supported by four steel girders spread gravel into the trench.
A screed which was a heavy plow-like beam spread and leveled the gravel beneath the harbor. The two-foot-deep gravel bed serves as the foundation for the immersed tube sections. Each of the 32 sections was 82 feet wide and 42 feet high.
They were transported by barge from Wiley Manufacturing's fabrication site in Fort Deposit, Maryland 45 miles south to the tunnel site. Once at the site, each of the sections was outfitted with interior and exterior work including the concrete roadway at a nearby outfitting pier over a week period before being submerged. Work began on the lowering of the tunnel sections in October The tunnel sections were submerged by a lay barge, which is comprised of two catamaran barges between which the tunnel section is submerged by lowering devices.
Laser guidance was used to lower the tube sections to within a few feet of the tube already in place. Divers connected the tubes using railroad-type coupling devices. Hydraulic jacks brought each lowered tube against the tube already in place. Once the dewatering valves at each end of the tube section were opened, thousands of tons of water pressure created by opening the valves moved the lowered tube section into its final position.
The final finishing work in the tubes did not begin until after the last section was lowered in April As work progressed beneath Baltimore Harbor, additional contracts were awarded for the tunnel's approaches. WEST SOUTH APPROACH: Work on the 2,foot-long approach included the building of an eight-lane depressed roadway, construction of a cut-and-cover reinforced concrete tunnel structure to connect the steel-tube section with the depressed roadway, removal and relocation of 2, feet of railroad tracks, and construction of a ventilation tower.
The toll plaza was not included in this contract, but rather under a separate contract. Each ventilation building contains 24 nine-foot-diameter ventilation fans; together, the 48 fans move up to 6.
Fresh air is blown from an eight-foot-high passageway beneath the roadway, while exhaust is drawn out through a seven-foot-high passageway above the tunnel ceiling.
The west ventilation building has a red brick facing and landscaped berm to better integrate the structure into the Locust Point community and the nearby Fort McHenry National Monument. The east ventilation building, which was built in a more industrial port area, is a conventional steel building with pre-cast concrete panels. Two innovations included the installation of high-intensity lighting at the tunnel's portals and the construction of antennas for AM and FM radio reception inside the tunnel.
However, this finishing work took its first and only fatality in when one worker was electrocuted and three others were injured in an accident at the tunnel's midpoint. When it opened, the Fort McHenry Tunnel was the widest underwater tunnel in the world, a title it still holds today. The files are in Adobe Acrobat format.
If you do not have Adobe Acrobat Reader, please click here to download a free copy of the program. The 5,foot-long immersed tube portion of the Fort McHenry Tunnel was built with the same construction method as that of the Ted Williams Tunnel in Boston, which was opened to traffic in The 2.
The tunnel was initially only opened to commercial traffic while local highway connections are completed. When the connection to the Massachusetts Turnpike is finished expected in the tunnel will complete from coast to coast. There were 76 cellular cofferdams, each 62 feet in diameter, altogether stretching for 5, linear feet, built as an outer perimeter to contain the fill as it was pumped there during the trench dredging.
Excerpt blue text : The Seagirt Marine Terminal stands as a working monument to the Port of Baltimore's innovative and progressive spirit. Opened in , Seagirt features the latest in cargo-handling equipment and systems.
The design behind this high-tech facility systems from one simple principle: keep the cargo moving. The computerized gate complex serves as the nerve center for the acre ha container terminal. Here's what the east approach looked like when it was under construction in July The steel tube elements from the harbor crossing will transition to a concrete cast-in-place tunnel just starting construction several hundred yards long, ending in the portal.
Notice the massive concrete gravity slabs under construction. They will range from 7 to 20 feet thick, designed to resist the hydrostatic pressure below sea level; the thickness increases as the tunnel grade slopes downward toward the harbor, reaching about 30 feet below sea level where the sunken tube tunnel begins. The gravity slabs extend for the full width of the approach tunnel and open depressed approach, and they literally serve as an "anchor" by providing enough weight to prevent the structure from "floating" upward from the pressure of the ground water.
The I Mall Tunnel in the District of Columbia and the I "bathtub" project in downtown Philadelphia used gravity slabs too, for the same reasons, where tunnels and open approaches were below sea level. The Fort McHenry Tunnel project is 8, feet long from grade point to grade point, and 7, feet from portal to portal. The sunken tube portion is 5, feet long, and was constructed as the Trench Tunnel Contract discussed above; and the roadway reaches a maximum depth of feet below harbor water surface level.
National recession and shortfall in state and federal highway funding in the early s caused heavy construction contractors to be hungry for work, and in many cases around the country they bid individual projects far below the agency estimate.
The West Approach contract included the relocation of existing railroads, the addition of 2, feet of new track, the construction of cut-and-cover cast-in-place reinforced concrete tunnel structure, the construction of open depressed approaches, and the erection of the west ventilation building.
The East Approach contract included the construction of cut-and-cover cast-in-place reinforced concrete tunnel structure, the construction of open depressed approaches, and the erection of the east ventilation building. The West Approach is longer than the East Approach, mainly to provide almost feet of covered land freeway to extend the underground freeway farther from Fort McHenry, and for a longer distance near the Locust Point neighborhood.
One of the eastbound tubes under construction, March , near the mid-point under the harbor, about feet below the surface of the water. The Fort McHenry Tunnel is a very unusual underwater tunnel, in that it is built on a long horizontal curve. Other tunnels are straight, making construction simpler. Of course, there is nothing simple about building an underwater tunnel. The contract for mechanical and electrical equipment was awarded to Howard P. Foley Co. This involved the installation of 48 9-foot-diameter ventilation fans, 24 in the west ventilation building and 24 in the east ventilation building, to move up to 6.
In each ventilation building, 12 of the fans are for supply and 12 are for exhaust. The tunnel complex has a very large system of electrical systems, as the entire tunnel has continuous signal, lighting and surveillance systems that require many hundreds of miles of wiring.
Fire fighting equipment is stationed throughout the tunnel, with water mains serving the hydrants. The tunnel has 28 pumps with a total capacity of 44, gallons per minute. Each ventilation building has the equivalent of a small power substation for converting the voltage of the power coming into the tunnel complex.
Again, opening day on I, looking west, just west of the west portals. I transitions from the tunnel to ground level to an elevated viaduct, which you can see in the distance.
The elevated freeway on the Locust Point Peninsula is about 3 miles long. Heading west, you can see the two two-lane roadways from the tunnels merge into a single four-lane roadway.
Greiner Company, Inc. ASCE Website. Excerpt blue text : Two tunnels beneath Baltimore Harbor are important routes for local traffic and a substantial portion of vehicles passing through the area on I, the East Coast's busiest and important highway for personal and commercial travel. The first of these, the Baltimore Harbor Tunnel, is designated I and was opened in
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