5-Why 解决问题工具.doc

U. S. Standard Railroad Gauge The U. S. standard railroad gauge (width between the two rails) is 4 feet, 8.5 inches. One might say thats an exceedingly odd number. Why was that gauge used? Because thats the way they built them in England, and English expatriates built the US railroads. Why did the English build them like that? Because the first rail lines were built by the same people who built the pre-railroad tramways, and thats the gauge they used. Why was that gauge used? Because the people who built the tramways used the same jigs and tools that they used for building wagons, which used that wheel spacing. Why did the wagons have that particular odd wheel spacing? Well, if they tried to use any other spacing, the wagon wheels would break on some of the old, long distance roads in England, because thats the spacing of the wheel ruts. Who built those old rutted roads? Imperial Rome built the first long distance roads in Europe (including England) for the Legions. The roads have been used ever since. What do we know about the ruts in the roads? Roman war chariots formed the initial ruts, which everyone else had to match for fear of destroying their wagon wheels. Since the chariots were made for (or by) Imperial Rome, they were all alike in the matter of wheel spacing. There you have it! The United States standard railroad gauge of 4 feet, 8.5 inches derives from the original specification for an Imperial Roman war chariot. Specifications and bureaucracies live forever. So the next time you are handed a specification and wonder what horses rear came up with it, you may be exactly right, because the Imperial Roman war chariots were made just wide enough to accommodate the back ends of two warhorses. Theres an interesting extension to the story about railroad gauges and horses behinds. When we see Space Shuttle Columbia sitting on its launch pad, there are two big booster rockets attached to the sides of the main fuel tank. These are solid rocket boost