tailieunhanh - Railroad Bridges

Railroad Bridges Introduction Railroad Network • Basic Differences between Railroad and Highway Bridges • Manual for Railway Engineering, AREMA 23 Railroad Bridge Philosophy Railroad Bridge Types Bridge Deck General • Open Deck • Ballast Deck • Direct Fixation • Deck Details Donald F. Sorgenfrei Modjeski and Masters, Inc. Design Criteria Geometric Considerations • Proportioning • Bridge Design Loads • Load Combinations • Serviceability Considerations W. N. Marianos, Jr. Modjeski and Masters, Inc. Capacity Rating General • Normal Rating • Maximum Rating Introduction Railroad Network The . railroad network consists predominantly of privately owned freight railroad systems classified according to operating revenue. | Sorgenfrei . Marianos Jr. . Railroad Bridges. Bridge Engineering Handbook. Ed. Wai-Fah Chen and Lian Duan Boca Raton CRC Press 2000 23 Railroad Bridges Donald F. Sorgenfrei Modjeski and Masters Inc. W. N. Marianos Jr. Modjeski and Masters Inc. Introduction Railroad Network Basic Differences between Railroad and Highway Bridges Manual for Railway Engineering AREMA Railroad Bridge Philosophy Railroad Bridge Types Bridge Deck General Open Deck Ballast Deck Direct Fixation Deck Details Design Criteria Geometric Considerations Proportioning Bridge Design Loads Load Combinations Serviceability Considerations Capacity Rating General Normal Rating Maximum Rating Introduction Railroad Network The . railroad network consists predominantly of privately owned freight railroad systems classified according to operating revenue the government-owned National Railroad Passenger Corporation Amtrak and numerous transit systems owned by local agencies and municipalities. Since the deregulation of the railroad industry brought about by the 1980 Staggers Act there have been numerous railway system mergers. By 1997 there remained 10 Class I major Railroads 32 Regional Railroads and 511 Local Railroads operating over approximately 150 000 track miles. The 10 Class I Railroads comprise only 2 of the number of railroads in the United States but account for 73 of the trackage and 91 of freight revenue. By far the present leading freight commodity is coal which accounts for 25 of all the carloads. Other leading commodities in descending order by carloads are chemicals and allied products farm products motor vehicles and equipment food and sundry products and nonmetallic minerals. Freight equipment has drastically changed over the years in container type size and wheelbase and carrying capacity. The most predominant freight car is the hopper car used with an open top for coal loading and the covered hopper car used for chemicals and farm .