The Baltimore Harbor Tunnel is a pair of two-lane road tunnels carrying Interstate 895—the Harbor Tunnel Thruway—under the Patapsco River southeast of downtown Baltimore, Maryland. Description The pair of tunnels is long, stretching from the south shore of the Patapsco River to the north shore near Dundalk. Each tunnel is wide and high, and accommodates two lanes in each direction. The maximum speed within the tunnel is . Two-way traffic may occur in either tunnel for overnight roadwork or during emergencies that close down one of the tunnels. The Tunnel has lane control signals to control which lanes are open, closed or as contra-flow traffic. 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 below ground to below ground. As of July 1, 2015, the toll rate for cars is $4.00 cash or $3.00 E-ZPass, paid in both directions. Vehicles with more than two axles pay additional amounts, up to $30.00 for six axles. In March 2020, all-electronic tolling was implemented as a result of the COVID-19 pandemic, with tolls payable through E-ZPass or Video Tolling, which uses automatic license plate recognition. All-electronic tolling was made permanent in August 2020. History 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 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. The project's costs would ultimately reach $150 million ($ million in ). The tunnel opened on November 29, 1957 with a dedication by Maryland Governor Theodore McKeldin and a crowd of 4,000 spectators. The initial toll for standard cars was forty cents. In the first 12 hours of operation, the tunnel handled an estimated 10,000 vehicles, mostly drivers from Maryland. In the same period, the tunnel also experienced its first collision (15 minutes after opening), first flat tire and first stalled vehicle. The tunnel was considered a success by the Maryland Transportation