Chinese Industry from the Air

industrial output, 1960s,
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Chinese Industry

of steam, and the open-hearth and Bessemer converter furnaces (for making steel from iron) and soaking pits (for equalizing temperatures in an ingot) emit smoke. Thermal power plants are usually heavy smokers. Cement plants in operation feature large quantities of smoke and dust. Many other industrial activities emit enough smoke or steam to be detected in the photography. Sometimes, as in power plants, the quantity of smoke may vary with the level of operation, but in most cases smoke only shows a facility to be active.
A better indicator of level of operation at many industrial plants is the extent of associated railroad activity. Many plants require a constant influx of raw materials and have a constant outflow of finished product by rail. The number of railroad cars at or near a plant is thus often significant.   A stockpile of raw materials-coal, ores, etc.-can give' a clue to the operational status of a plant, but this indicator is unreliable and often misleading. Often the size of the stock of raw materials is inversely related to the operational level of the plant, and sometimes it is static regardless of plant operation.
An important variable in determining operational status is the frequency of photographic coverage needed. In a number of industries, fortunately, particularly those that use large furnaces, frequent shutdown is not practical. Once temperatures are raised to operating levels, operation is continued for a long time before shutdown for maintenance or other reasons. Thus one can forego aerial coverage for fairly long periods with reasonable confidence that if a plant of this kind was operating before and after, it was probably operating during the interval as well. The length of the period will vary among industries; the PI, as he progresses in the mastery of his profession, will use his judgment in respect to it.
At new construction in progress, aerial photography offers a ringside seat. Starts can be identified early if they involve clearing or grading the site, and the entire construction cycle can then be followed, including the laying of access roads or railroad spurs, the erection of security fences, and the completion of administration buildings. The enlargement of an existing plant can be watched in the same way. For the internal modification of existing facilities there are clues such as the presence of building materials or equipment, but the insight they offer is obviously quite limited.


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Posted: May 08, 2007 08:11 AM
Last Updated: Aug 05, 2011 12:46 PM