Interstate 895 (I-895) is an auxiliary Interstate Highway in the US state of Maryland. Known as the Harbor Tunnel Thruway, the highway runs between one junction with I-95 in Elkridge and another interchange with I-95 on the east side of Baltimore. I-895 is a toll road that crosses the Patapsco River estuary via the Baltimore Harbor Tunnel, connecting U.S. Route 1 (US 1), I-695, and the Baltimore–Washington Parkway (B–W Parkway) in the southwestern suburbs of Baltimore with US 40 on the east side of Baltimore. In conjunction with a pair of spurs, unsigned I-895A and I-895B, I-895 provides access to the tunnel from I-97 and Maryland Route 2 (MD 2) in Glen Burnie. The highway is designed for through traffic by having partial interchanges that require vehicles from almost all starting points (with the two northernmost exits being exceptions) to pass through the tunnel and the tunnel toll plaza, where a $4.00 toll is charged to passenger vehicles, before exiting the facility. The idea of a crossing of the Patapsco River south of Downtown Baltimore had been studied since the 1930s. In the early 1950s, the Maryland State Roads Commission (SRC) chose to construct a four-lane tunnel between the Canton and Fairfield neighborhoods of Baltimore and approach highways to connect the tunnel with major highways to Washington, D.C.; Annapolis; Richmond, Virginia; and Philadelphia, Pennsylvania. The tunnel and approach highways were constructed beginning in 1955 and opened in November 1957, opening a bottleneck for Baltimore through traffic, which formerly had to navigate the city streets. The Harbor Tunnel Thruway was connected with the John F. Kennedy Memorial Highway in the early 1960s and the portion of I-95 south to Washington DC in the early 1970s. With these connections, I-895 was burdened with most of the through traffic passing through Baltimore. The congestion was not resolved until I-95 through Baltimore was completed when the eight-lane Fort McHenry Tunnel opened in November 1985. The transfer of most traffic to the new tunnel allowed the Baltimore Harbor Tunnel to be partially shut down for extensive maintenance in the late 1980s. Route description I-895 is maintained by the Maryland Transportation Authority (MDTA) and, like all Interstate Highways, is a part of the National Highway System for its entire length. Western approach I-895 begins at exit 46 of I-95 in Elkridge with single-lane flyover ramps from northbound I-95 to I-895 and from I-895 to southbound I-95.