I-195 parallels the railroad south to its partial cloverleaf interchange with MD 295 (Baltimore–Washington Parkway), which contains a flyover ramp from southbound MD 295 to eastbound I-195. I-195 curves southeast and passes under the BWI Trail ahead of its partial cloverleaf interchange with MD 170 (Aviation Boulevard), also known as the Airport Loop. The Airport Loop provides access to long-term parking lots, the consolidated rental car facility, hotels, cargo and general aviation facilities, and BWI Rail Station serving Amtrak and MARC Train. The circumferential highway also provides indirect access to I-97 for traffic heading to Annapolis or the Chesapeake Bay Bridge. At this interchange, I-195 ends and the roadway continues toward the entrance to BWI Airport. Like all Interstates, I-195 is a part of the National Highway System for its entire length. History Friendship International Airport was constructed between 1947 and 1950 as the new primary airport for Baltimore. To directly connect the airport with Baltimore, an access road was planned to link the new Baltimore–Washington Expressway, later designated MD 295, with the airport terminal. The first portion of the Friendship International Airport Access Road was completed from a full Y interchange at the expressway to an interchange with MD 170 in October 1949 and designated MD 46. The access road was completed from MD 170 to the airport terminal in July 1951, about the same time the expressway was completed between MD 46 and Downtown Baltimore. The remainder of what is now I-195 was planned as early as 1969, when the portion of Metropolitan Boulevard north of US 1 was placed under construction. The freeway opened from the US 1 ramps northwest through the I-95 interchange to an intersection with Sulphur Spring Road just south of the modern Selford Road overpass in August 1974. The freeway was extended to its present terminus at Rolling Road and the ramps to UMBC Boulevard were constructed in 1975. Metropolitan Boulevard south of the I-95 interchange was marked as a second segment of MD 46 from when it opened. North of I-95, the freeway was marked as a relocation of MD 166. That segment of MD 46 was renumbered as an extension of MD 166 by 1981. The missing connection between US 1 and MD 295 resulted in a circuitous path for traffic between I-95 and BWI Airport. In 1974, that route involved exiting I-95 at MD 100, which then served as a