早期的铁路,传达上级命令、站与站之间的信息传输一般都是靠电话线来完成的。今天,虽然无线电和卫星通讯已经早已替代了铁路曾经用过的电线网络,但在一些铁路沿线,你仍能见电线杆子。 In the early days, railroads communicated orders from their superiors. The transmission of information between stations was usually done by telephone lines. Today, while radio and satellite communications have long replaced the wireline network that railroads have used, you can still see wire poles along some of the railroads.