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Wrought-Iron and Steel Rails |
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Wrought-Iron and Steel Rails | Cast Iron Rail | Steel Track
Steel tracks create an intricate pattern at this French railway junction. The manufacture of steel tracks in the United States in 1865, along with other developments in metal technology, made it possible to transport heavier loads over the rails (Wrought-Iron and Steel Rails, Cast Iron Rail, Steel Track). The first improvement on cast-iron rails were rails of wrought iron, introduced in 1820 in England, where the first steel rail was also manufactured. The manufacture of steel rails in the United States began in 1865, and they are now used throughout the world. Metallurgical advances in the 20th century greatly improved the quality of rail steel. Previously, transverse fissures or cracks often developed inside rails during use, until engineers discovered that the flaws from which these cracks spread were formed when rails hot from the rolling mill were cooling. All rails manufactured for use in the United States now undergo a process of controlled cooling and inspection to prevent such defects. Usually they are also hardened at the ends by heat treatment (Wrought-Iron and Steel Rails, Cast Iron Rail, Steel Track). Heavier trains requiring stronger track resulted in much heavier rails. The iron rails used in early railroading weighed less than about 20 kg/m (about 40 lb/yd), and the steel rails used at the beginning of the 20th century in many cases were not heavier than about 30kg/m (about 60 lb/yd). In the 1930s rails weighing 50 kg/m (100 lb/yd) or more, or in some instances more than about 65 kg/m (about 130 lb/yd) were used. Rails manufactured today for main-line use may weigh as much as 75.5 to 77 kg/m (152 to 155 lb/yd) (Wrought-Iron and Steel Rails, Cast Iron Rail, Steel Track). Wrought-Iron and Steel Rails | Cast Iron Rail | Steel Track |
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Wrought-Iron and Steel Rails | Cast Iron Rail | Steel Track |
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GOVERNMENT REGULATION OF RAILROADS: • INTRODUCTION • STATE REGULATION • FEDERAL REGULATION • EARLY 20TH-CENTURY REGULATION • THE DEPRESSION YEARS • POSTWAR ENACTMENTS • DEREGULATION MOVEMENTS |
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