Railroad tracks, crossing

To understand the need for standards, the easiest method is to envision a world without them. In that world, riders change trains at every national border or even city border because different railroad track widths require different railroad cars and engines. Crossing the border is difficult if you are not from one of the two countries because there is not standard format for identification. Manufacturers make dozens or hundreds of versions of each product because of different electrical or mechanical requirements and must charge for the differences and for huge inventories. Credit cards can only be used for a single chain of stores and banks charge a lot of money to process them. And there is no telephone service across borders. The Internet is both... 

Phospholipids of the composition present in cells spontaneously form sheetlike phospholipid hilayers, which are two molecules thick. The hydrocarbon chains of the phospholipids in each layer, or leaflet, form a hydrophobic core that is 3-4 nm thick in most biomembranes. Electron microscopy of thin membrane sections stained with osmium tetroxide, which binds strongly to the polar head groups of phospholipids, reveals the bilayer structure (Figure 5-2). A cross section of all single membranes stained with osmium tetroxide looks like a railroad track two thin dark lines (the stain-head group complexes) with a uniform light space of about 2 nm (the hydrophobic tails) between them. 

Approach an elevator at right angle to the gate, and stop at least 5 feet from the gate imtil permitted to proceed on elevators, operators should shift into park or neutral, set brakes, shut off power, and dismount. Drive carefully over bridge plates, which must be properly secured cross railroad tracks on a diagonal when possible park at least 8 feet from the nearest rail. 

The driver must be required to slow down and sound the horn at cross aisles and other locations where vision is obstructed. If the load being carried obstructs forward view, the driver must be required to travel with the load trailing. Railroad tracks must be crossed diagonally wherever possible. Parking closer than eight feet from the center of railroad tracks is prohibited. 

At railroad tracks, slowly cross at an angle so that the lift truck is not damaged and that the load is not affected. 

There is a potential for growth of the rubber railroad crossing market. There are 185,800 public railroad crossings and at least as many private ones in the U.S. Less than 2 percent have rubber crossings. A typical railroad crossing consumes about 350 pounds of rubber per track foot. 

Railroad steam has gone the way of the paddlewheel, replaced on the nation s commuter and cross-country railways by diesel oil and electricity. For decades, railways themselves have been in decline. Intercity passenger travel is dominated by the automobile and the plane. The truck is king of the road for freight hauling. Speed and convenience are the obsessions that have forced the train off to a siding, if not off the track altogether. 

In the field of rail welding, the thermite process supplements and sometimes replaces flash or gas-pressure welding. The latter methods require very costly factory installations. They furnish rails about one-quarter of a mile long, which are hauled to the point of field installation. Here one can resort to the old-fashioned mechanical join-Ing (a source of most maintenance on a railroad) or use field welds. The best of these is the thermite weld. It may be used exclusively with specialty items such as crossings, for haulage tracks in coal mines, and for crane rails. ... 

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