<P> The pair of tunnels is 1.45 mi. 7,650 feet (2.33 km) long, stretching from the south shore of the Patapsco River to the north shore near Dundalk . Each tunnel is 22 feet (6.7 m) wide and 14 feet (4.3 m) high, and accommodates two lanes in each direction . The maximum speed within the tunnel is 50 miles per hour (80 km / h). </P> <P> Both portals have ventilation buildings, with a total of 32 fans in place to replace the air within the tunnels, which is drawn in through the tunnel floors and exhausted through the tunnel ceilings . The tubes themselves range from a depth of 50 feet (15.2 m) below ground to 101 feet (30.8 m) below ground . </P> <P> As of July 1, 2015, the toll rate for cars is $4.00 cash or $3.00 E-ZPass, paid in either direction . Vehicles with more than two axles pay additional amounts, up to $30.00 for six axles . </P> <P> The tunnel and approaches were designed by Singstad and Baillie, a New York - based engineering firm specializing in tunnel design, in association with the J.E. Greiner Company, a local Baltimore - based firm . The tunnel was formed out of twenty - one 310 - foot (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, 1956 . The remainder of the tunnel was constructed using the cut - and - cover method, extending from the submerged tubes to the north and south portals . </P>

What is the toll for the baltimore harbor tunnel
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