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Monitor-Merrimac
Memorial Bridge-Tunnel (MMMBT) is the 4.6 mile-long (7.4 km) Hampton
Roads crossing for Interstate 664. It is a four-lane bridge-tunnel
comprised of bridges, trestles, man-made islands, and tunnels under a
portion of the Hampton Roads harbor where the James, Nansemond, and
Elizabeth Rivers come together in South Hampton Roads, in the
southeastern portion of Virginia in the United States.
It
connects the independent cities of Newport News on the Virginia
Peninsula and Suffolk in South Hampton Roads and is part of the Hampton
Roads Beltway
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Interstate
664 is the 20.7-mile-long freeway that connects I-64 in Hampton to
I-64/I-264 in Chesapeake, completed in April 1992. I-664 includes the
4.6-mile Monitor-Merrimac Memorial Bridge-Tunnel (MMMBT). The MMMBT
cost $400 million to build, and it includes a four-lane tunnel that is
4,800 feet long, two man-made portal islands, and 3.2 miles of twin
trestle. Northbound on the MMMBT is one of the most spectacular views
on any road I know of; Hampton Roads makes a "V" with one branch to
your ten o'clock, and the other branch to your two o'clock. You see an
enormous expanse of water, left, right, and ahead of you, with the
landfall of the Peninsula dead ahead. On the ten o'clock branch, you
see the Newport News Marine Terminal and Shipyards, on the two o'clock
branch, you see the Norfolk Naval Base. Typically, you will see a
couple Nimitz-class aircraft carriers moored in the distance, and many
other ships. Another nice feature, is that the MMMBT is toll-free. The
name comes from the fact that the duel between the two Civil War
ironclads was fought less than a mile from the where the tunnel is
today.
The
tunnel is 4,800 feet long from portal to portal, and it was built by
the immersed sunken tube method, comprised of 15 prefabricated
segments each 300 feet long and with two 2-lane bores, placed by
lay-barges and joined together in a trench dredged in the bottom of
the harbor, and backfilled over with earth. Four percent (4%) maximum
grades are utilized in the tunnel, and a 60 mph design speed. The
traffic lanes in the tunnel are 13 feet wide, with 2.5-foot-wide
ledges on either side of the roadway, and with 16.5 feet of vertical
clearance from the roadway to the ceiling. The current shipping
channel above the deepest part of the tunnel, has 800 feet of
horizontal width and 45 feet of vertical depth below the average
low-tide water level; and the tunnel was designed and built deep
enough to allow for a future enlargement of the shipping channel to
1,000 feet of horizontal width and 55 feet of vertical depth below the
average low-tide water level.