美国铁路目前总延展长度为0.9Mkm(轨道总延长实为0.47Mkm——编者注)营业铁路正线里程为0.295Mkm,平均每延长米钢轨重量为54.6kg。美国铁路网所铺钢轨总重为56Mt,每米钢轨价值40美元。每公里轨道(包括钢轨扣件等附属设备)价值平均约为15万美元。在上个世纪末,美国生产的钢轨品种繁杂,达100余种,按重量甚至可划分为20余个等 The total extension of the U.S.A. is 0.9Mkm (0.47Mkm total rail extension). The positive mileage of the commercial railways is 0.295Mkm, with an average of 54.6kg per extension rail. The U.S. rail network paved the way for a total rail weight of 56Mt, with a rail cost of US $ 40 per meter. The average value per kilometer track (including ancillary equipment such as rail fasteners) is about $ 150,000 on average. At the end of the last century, the variety of railroad tracks produced by the United States reached more than 100 species and could even be divided into more than 20