【正文】
Even federal and state highways did not follow basic standards. Some states allowed trucks up to 36,000 pounds, while others restricted anything over 7,000 pounds. A government study remended a national highway system of 33,920 miles, and congress passed the FederalAid Highway Act of 1944, which called for strict contractcontrolled design criteria. The interstate highway system was finally launched in 1956 and has been hailed as one of the greatest public projects of the century. To build 11 its 44,000 mile web of highways, bridges, and tunnels, hundreds of unique engineering designs and solutions had to be worked out. Consider the many geographic features of the country: mountains, steep grades, wetlands, rivers, deserts and plains. Variables included the slope of the land, and the ability of the pavement to support the load. Innovative designs of roadways, tunnels, bridges, overpasses, and interchanges that could run through or bypass urban areas soon began to weave their way across the country, forever altering the face of America. Longspan, segmentedconcrete, cablestayed bridges such as Hale Boggs in Louisiana and the Sunshine Skyway in Florida, and remarkable tunnels 12 like Fort MC Henry in Maryland and Mr. Baker in Washington developed under the nation39。在 開始修建的那一年 ,艾森豪威爾 將軍 曾說: “ 通 7 信 系統(tǒng) 和交通 運輸 系統(tǒng) 聯(lián)合起來的巨大 力量 正 是 我們國家 最重要的活力來源。 公路系統(tǒng)并不僅僅是通過提供運輸線路來影響美國的經(jīng)濟,它還促使了很多附屬產(chǎn)業(yè)的產(chǎn)生和發(fā)展,比如說服務站、汽車旅館、飯館以及購物中心。高速公路上的事故死亡率僅為美國其他道路的一半(高速公路旅客周轉(zhuǎn)量 1億人英里的死亡率是 ,而其他公路旅客周轉(zhuǎn)量 1 億人英里的死亡率則是 )。過去是以生產(chǎn)推動銷售,物流模式的特點是高庫存;而現(xiàn)代企業(yè)生產(chǎn)方式則是市場需求拉動生產(chǎn),相應的物流模式也由高 效率、低成本的 運輸系統(tǒng) 和信息系統(tǒng)替代高庫存。能夠 貫穿 或繞過城市區(qū)域的 創(chuàng)新設計 —— 其中包括車行道 、 地下 隧道、橋梁、 人行 天橋 以及 立交橋等 很快地 在全國各地涌現(xiàn)出來, 并且 永遠 地 改變了美國的面貌。為 了修建長達 44000 公里的公路 、 橋梁 、 隧道網(wǎng),人們 必須 制定 出 數(shù)以百計的有針對性的 特殊 工