在亚利桑那州施工的新型Tempe Town Lake大桥已经进入最后施工阶段。1530英尺长耗资2150万美元的大桥将用于Valley Metro轻轨工程。这座桥包括两个钢管桁架，横跨Tempe Town湖的南北方向，联系了Phoenix和Tempe ,Mesa以及其它临近的地区。它在Valley Metro轻轨线的最初的20英里中提供了重要的线路。每一个桁架要承受磁轨，一个桁架通向一个方向。Valley Metro鉴于美学、刚性和强度选择了钢管桁架的形式。
这种管桁架截面是三角形横截面，它在几何形式上补充了附近三座大桥：两座混凝土拱形桥和一座1912年建成的历史悠久的矩形截面的铁路桥。这种新型轻轨桥仅占用了Union Pacific Railroad.铁路桥的50英尺。
创新型设计
一般工程顾问和Valley Metro Rail基于共同的讨论和和大众调查起初针对这座桥提出了三套方案。State History Preservation Office否定了所选的第一套方案。Seattle artist Buster Simpson和设计方TY Lin最后提出了一个全新的最终设计概念——每个轨道方向设计成一个创新型的、连续的、11跨三角形截面的管桁架结构。甲方乙方都非常兴奋地在这个新颖的设计上面签了字。
完成之后一年在2004年7月这座桥的细部设计开始了。这座桥依照AASHTO Load Factor Design标准，使用50ksi强度的钢管。结果很浅的刚性大跨结构和现存的桥结构非常吻合并且给Tempe市提供了一个很美的入口。电脑控制发光二极管使它能够沿着每个桁架的中心线传播。一种白色半透明的纤维制品，它能够反射和传递有色光，在列车通过该桥的时候它能够跟踪列车。
Innovative Bridge in Arizona to Carry Light Rail
By Dan Heller P.E., and Gary Gardner
Construction of the innovative Tempe Town Lake Bridge in Arizona has reached final stages.Measuring1,530 feet long, the ＄21.5 million bridge will serve the Valley Metro Light Rail Project. Consisting of two steel pipe trusses, the bridge crosses north-south over Tempe Town Lake, connecting Phoenix to Tempe ,Mesa and other neighboring communities. It provides a critical link in the initial 20-mile Valley Metro light rail line. Each truss carries a track , one truss for each direction. Valley Metro selected a pipe truss design for its aesthetics, stiffness, and strength.
The pipe trusses have a triangular cross-section, which complements the geometry of three nearby bridges: two concrete arch bridges and a historical railroad bridge of rectangular cross section built in 1912. The new light rail bridge resides just 50 feet from the railroad bridge, which belongs to the Union Pacific Railroad.
Innovative Design
The general engineering consultant( GEC)and Valley Metro Rail originally presented three designs for the bridge, based on community discussions, for public review. The State History Preservation Office rejected the first design selected. The design firm TY Lin, along with Seattle artist Buster Simpson, subsequently developed a new final design concept——an innovative, continuous, 11-span triangular steel pipe truss for each track direction. All parties enthusiastically endorsed this novel design.
