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|direction_b=North |terminus_b= at the Pennsylvania state line near Maugansville |counties=Washington |previous_type=MD |previous_route=80 |next_type=MD |next_route=81 }} Interstate 81 (I-81) is a part of the Interstate Highway System that runs from Dandridge, Tennessee to Fishers Landing, New York. In Maryland, the Interstate highway runs from the West Virginia state line at the Potomac River in Williamsport north to the Pennsylvania state line near Maugansville. I-81 is the primary north–south Interstate highway in Washington County, connecting Hagerstown with Chambersburg and Harrisburg to the north and Martinsburg, Winchester, and Roanoke to the south. The idea of a north–south bypass of Hagerstown to relieve congestion on the contemporary main highway through the Hagerstown Valley, U.S. Route 11 (US 11), predates the Interstate system. Construction on the Hagerstown Bypass began in the mid-1950s and was completed in 1958 from US 40 north to the Pennsylvania state line. I-81 was assigned to the new freeway in 1959. The southern section of the freeway from the Potomac River to US 40 was built starting in 1962 and completed in 1966. Beyond interchange improvements, I-81 has changed very little from the four-lane freeway of the 1960s. Long-range plans call for widening I-81 to six lanes and effecting further interchange improvements along what is a major commuting and trucking corridor. ==Route description== I-81 crosses the Potomac River from West Virginia and enters Maryland as a four-lane freeway with a speed limit of . The Interstate curves to the northeast around Williamsport, where the highway meets MD 68 and MD 63 (Lappans Road) at a diamond interchange (Exit 1) to the south of the town and US 11 (Virginia Avenue) at a five-ramp partial cloverleaf interchange (Exit 2) to the east. Beyond US 11, I-81's speed limit drops to . The Interstate passes along the edge of the Hagerstown suburb of Halfway, where the highway meets I-70 (Eisenhower Memorial Highway) at a cloverleaf interchange (Exit 4) with collector-distributor lanes on both I-81 and I-70. Traffic for I-68 is advised to use I-70 west. I-81 meets Halfway Boulevard, which leads to several shopping centers including the Valley Mall, at a six-ramp partial cloverleaf interchange (Exit 5).〔〔 I-81 continues northeast along the west edge of Hagerstown. The Interstate crosses CSX's Lurgan Subdivision and passes under MD 144 (Washington Street) with no access before reaching a cloverleaf interchange with US 40 (National Pike) (Exit 6). The freeway intersects MD 58 (Cearfoss Pike) at a partial cloverleaf interchange (Exit 7). Immediately to the north, I-81 has a partial interchange with Maugansville Road (Exit 8) featuring a loop exit ramp from southbound I-81 and a straight entrance ramp to the northbound direction. The Interstate curves to the north and crosses Norfolk Southern Railway's Lurgan Branch. The speed limit increases to as the Interstate passes along the eastern edge of Maugansville, where the highway meets Maugans Avenue at a diamond interchange (Exit 9). I-81 meets Showalter Road, which is used to access Hagerstown Regional Airport, at a cloverleaf interchange (Exit 10) as the freeway gently curves around the airport's runway. The Interstate heads northeast to the Pennsylvania state line, on top of which the highway meets PA 163 (Mason Dixon Road) at Exit 1 of the Pennsylvania exit sequence. The southbound exit ramp to and entrance ramp from PA 163 are in Maryland and the northbound ramps are in Pennsylvania.〔〔 I-81, like all Interstate highways, is a part of the National Highway System for its entire length.〔〔 It is the shortest mainline Interstate in Maryland and contains the shortest portion of I-81 of all six states through which the Interstate highway passes. The Interstate was dedicated as Maryland Veterans Memorial Highway in 1987.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Interstate 81 in Maryland」の詳細全文を読む スポンサード リンク
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