Highway lighting

Figure 7.23 Scxlium vapor lamps, which are used for commercial and highway lighting, have a yellow glow due to the emission from excited sodium atoms. 

Eor example, street lamps use the emissions from excited sodium atoms, the dazzling colors of a fireworks display come from photons emitted by metal ions in excited states, and the red light in highway flares often comes from excited Sr ions. 

Light of wavelength 589 nanometers falls in the yellow portion of the visible region of the electromagnetic spectrum. The characteristic yellow glow of sodium vapor lamps used to illuminate many highways results from this particular emission. 

Carbon monoxide is produced by the incomplete combustion of fossil fuels, and in major urban areas of developed nations a major source is the exhaust from light-duty motor vehicles (LDMV). Figure 2.7 shows the distribution of sources within the United States in 1996. A total of 89 X 106 short tons, or 81 Tg, of CO were emitted, about 60% of which comes from highway vehicles (EPA, 1997). 

Colored light compositions are used in the form of a loose powder, or are tamped into paper tubes in torches for political parades, for highway warnings, and for railway and marine signals, in Bengal lights, in airplane flares, and in lances for set pieces, or are prepared in the form of compact pellets as stars for Roman candles, rockets, and aerial bombs, or as stars to be shot from a special pistol for signaling. 

By Truck. Motor vehicle shipment of hazardous materials is covered in Dept of Transportation Tariff No 11 (Ref 4). Motor vehicle shipment is more complex than rail shipment. A train is made up of many cars watched over by an engineer in front and caboose personnel behind. The engineer is in voice communication with the tower the railroad controls traffic over its route and provides trained inspectors. In contrast, each truck is an independent unit. It has no control over traffic on the public highway and the driver must cope with any situation which may arise. Hence, drivers of hazardous materials are given careful training and detailed instructions, and the vehicle is carefully inspected for safety (lights, brakes, etc) and compliance with local laws (wt limit, etc)... 

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