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}} The Interstate Bridge (also Columbia River Interstate Bridge, I-5 Bridge, Portland-Vancouver Interstate Bridge, Vancouver-Portland Bridge) is a pair of nearly identical steel vertical-lift, "Parker type" through-truss bridges that carry Interstate 5 traffic over the Columbia River between Vancouver, Washington and Portland, Oregon in the United States. The bridge opened to traffic in 1917 as a single bridge carrying two-way traffic. A second, twin bridge opened in 1958 with each bridge carrying one-way traffic. The original 1917 structure is the northbound bridge. As of 2006, the bridge pair handles around 130,000 vehicles daily.〔 The green structure, which is over long, carries traffic over three northbound lanes and three southbound lanes. It was added to the National Register of Historic Places in 1982, as the "Portland–Vancouver Highway Bridge".〔 〕 Since 2005, proposals for replacing the bridge have been produced and debated. The bridge is considered responsible for traffic congestion of road vehicles and river traffic. Plans for a replacement bridge, known as the Columbia River Crossing (CRC) project, estimated to cost at least $3.4 billion, had come together by 2012 after many delays, but were very controversial, with both strong support and strong opposition. In late June 2013, the CRC project was canceled, after the Washington state legislature declined to authorize funding for the project.〔 The Interstate Bridge's name is a simple descriptive one based on its location, as a bridge connecting two states.〔 In 1917, the new bridge gave its name to a Portland arterial street. Shortly before the bridge opened, a pair of streets through North Portland that were planned to be treated as the main route to and from the bridge, Maryland Avenue and Patton Avenue, were renamed Interstate Avenue.〔"Street Name Changed: Maryland and Patton Avenue become Interstate Avenue" (December 7, 1916). ''The Morning Oregonian'', p. 13.〕 ==First bridge== The bridge was built to replace an overcrowded ferry system operated by Pacific Railway, Light & Power Co. Construction on the bridge began in March 1915, following the sale of bonds. The first bridge was opened on February 14, 1917 at a cost of $1.75 million (equivalent to $ million in ), which was shared between Clark County and Multnomah County. Clark County paid $500,000 and Multnomah County $1,250,000—probably proportional to population.〔Horner, John B. (1919). "Oregon: Her History, Her Great Men, Her Literature". The J.K. Gill Co.: Portland.〕 The first bridge has a total of 13 steel spans, with three measuring in length and the remaining ten spans each.〔 Piers sit atop pile caps on wooden pilings approximately 70 feet deep. One of the spans is the lift span for allowing river traffic under the bridge.〔 The lift span is capable of moving vertically, and provides of clearance below when fully raised.〔 The towers are tall, above the roadway.〔 The original paved roadway was wide and had a wide sidewalk.〔 It was the first automobile bridge across the river between Washington and Oregon,〔 and the second to span the river at all, after the Wenatchee Bridge of 1908. It was originally a toll bridge costing 5¢ per vehicle or per horse and rider,〔 equivalent to $ in . In 1928 the states of Washington and Oregon jointly purchased the bridge from the counties and discontinued tolling the following year.〔 Electric streetcars operated across the bridge from opening day in 1917〔"Columbia Span Is Formally Opened: Dream of Half Century Is Realized (subheadlines: Traffic Starts With Brilliant Ceremony on Bridge; Thousands Attend Affair)". (February 15, 1917). ''The Morning Oregonian'', p. 1.〕 until 1940. The bridge's deck carried dual gauge track,〔 to accommodate both Vancouver's standard gauge cars and Portland's gauge cars. Before the bridge, Portland had a Vancouver streetcar line since 1893, but it ran to Hayden Island, where passengers transferred to a ferry owned by the street railway company to continue across the river to Vancouver.〔Thompson, Richard H. (2010). ''Portland's Streetcar Lines'', pp. 72–73, 77. Arcadia Publishing. ISBN 978-0-7385-8126-2.〕 Streetcar service across the Interstate Bridge ended on September 3, 1940.〔 The bridge became part of then-new Interstate 5 in 1957.〔 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 Bridge」の詳細全文を読む スポンサード リンク
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