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The High Five Interchange is the first five-level stack interchange built in Dallas, Texas. Located at the junction of the Lyndon B. Johnson Freeway (Interstate 635, I-635) and the Central Expressway (US Highway 75, US 75), it replaces an antiquated partial cloverleaf interchange constructed in the 1960s. The $261 million project was initiated in 2002 and completed in December 2005. It was designed by the HNTB Corporation and built by Zachry Construction Corporation. The interchange is considered by ''Popular Mechanics'' to be one of "The World's 18 Strangest Roadways" because of its height (as high as a 12-story building), its 37 permanent bridges and other unusual design and construction features. In 2006, the American Public Works Association named the High Five Interchange as "Public Works Projects of the Year".〔 ==Description== The High Five Interchange, north of downtown in Dallas, Texas, is a massive five-level freeway interchange. It is the junction of two major highways carrying heavy rush hour traffic, the Lyndon B. Johnson Freeway (Interstate 635) and the Central Expressway (US 75), and is the first five-level stack interchange to be built in the city. It replaces the antiquated three-level, modified cloverleaf interchange built in the 1960s that caused a severe bottleneck by narrowing US 75 down to two lanes at the junction of the two highways. The looped ramps of the cloverleaf forced motorists to slow down drastically, backing up traffic. Left-hand exits contributed to the congestion. Further, its two frontage roads were not directly connected to each other, making local access difficult. Alluding to the celebratory gesture, the "High Five" name refers to the five interchange ramps that tower over the landscape. The interchange is as high as a 12-story building,〔 and includes 37 bridges spread across five levels (the "High Five"), 710 support tiers, and 60 miles of additional highway. The highest ramps are above ground. The lanes of US 75, which are on the bottom level, are below ground level.〔 As part of the project, I-635 was widened to include four dedicated high-occupancy vehicle lanes (HOV lanes) that are barrier-separated and reversible. The roads on the five levels are:〔 *Level I: US 75, an eight lane highway, four lanes going each way *Level II: The junction of the two six-lane frontage roads, each having three through lanes in each direction, left-turn lanes and turnarounds, and easy access to US 75 and I-635 *Level III: I-635, ten regular lanes, five going each way, and four HOV lanes (two going each way) separated by barriers *Level IV and V: Direct connection ramps (two levels), eliminating the left exits of the modified cloverleaf The interchange, with its decorative etchings on precast concrete elements, along with the visually appealing coloration specified by the Texas Department of Transportation (TxDOT),〔 can be regarded as an enormous work of public art.〔 The High Five also incorporates a hiking and bike trail, named the Cottonwood Trail, which runs under all levels of the interchange. The section of the trail passing beneath the interchange was constructed as part of the High Five project by TxDOT. The interchange is considered by ''Popular Mechanics'' as one of "The World's 18 Strangest Roadways", calling it a "labyrinth of lanes" and a "five-level marvel of engineering" because of its height, the number of its bridges and other unusual design and construction features.〔 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「High Five Interchange」の詳細全文を読む スポンサード リンク
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