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In the U.S. state of Oregon, Interstate 5 traverses the state from north to south, passing through the major cities of Portland, Salem, Eugene, and Medford. ==Route description== Beginning with the section about north of the California border, the highway runs from Siskiyou Summit, the highest point on I-5,〔 (42|3|40.47|N,122|36|24.08|W(GoogleEarth) ) 〕 through Oregon's southern mountains and towns such as Ashland, Medford, and Grants Pass. Past Roseburg, the mountains turn into hills, and as it reaches Eugene, the road enters the Willamette River Valley. At Eugene the highway intersects with the short Interstate 105. The interstate then heads almost due north, skirting near Albany and Corvallis, and passes through Salem. There were plans〔 ("The Interstate Highway System in Oregon - A Historic Overview" ), (pdf, page 62) ''Oregon Department of Transportation'' 〕 to build a spur into Salem, called Interstate 305. In the Salem area, placed in the median near mile marker 260, are signs noting where I-5 crosses the 45th parallel. It bears the words "45th Parallel - Half Way Between the Equator and North Pole". The highway then tracks a little to the northeast, crossing the Willamette River on the Boone Bridge and passing through the city of Wilsonville before splitting off Interstate 205 south of the Portland metro area. From here it passes up through Tualatin and Tigard along former U.S. Route 99W and through the so-called Terwilliger curves before hitting the southern terminus of I-405 and the Marquam Bridge. Also planned was a spur in Portland off I-405, called Interstate 505, which would have connected to U.S. Highway 30, but that plan was canceled. A stub of what would have been I-505 exists as a long exit ramp to Highway 30. After crossing the Willamette River on the Marquam Bridge, I-5 has junctions at the western terminus of Interstate 84 and the northern terminus of I-405. It then continues through the northern parts of the city of Portland, and crosses into Washington via the Interstate Bridge. Notably, bicycles are not prohibited from most of I-5 in Oregon, perhaps because in rural and mountain areas, few or no alternate routes exist (having been largely built over the alignment of U.S. 99, which in many places was laid over historic trails). In the early 1970s, restrictions against non-motorized vehicles began appearing in denser urban areas where such use would be unsafe, but, as of April 2007, the rest remains accessible.〔http://www.oregonlive.com/news/oregonian/index.ssf?/base/news/1156991119175710.xml&coll=7〕 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 5 in Oregon」の詳細全文を読む スポンサード リンク
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