HUGE SKYSCRAPERS

Evening Post, Volume CVIII, Issue 102, 26 October 1929, Page 24

HUGE SKYSCRAPERS

•J 50 STORIES HIGH

Sky-scrapers with about 150 floors, almost two-fifths of a mile high, or nearly four times the height of Washington monument, now ean.be built ■with safety, says a writer in the San Francisco "Chronicle." ', ; But .their "economic height," for the best rental profits, is around seventy-five stories. This economic top ss limited at present' in Chicago; Detroit, New- York, and possibly '[ a few other American cities where landvvalues are- extremely high. These statements summarise a report issued by the American Institute of Steel Construction. It is based on two years research to learn tho skyscraper limit, and the "economic considerations" which "will be the determining factor in this as in other fields of human progress." The skyscrapers forecast are of the present setback or tower architecture. In their probable spread is seen a modified type of a big city, in which co-op-erative endeavour provides increased facilities for health and comfort. Each building is likely to occupy a full city block, he says. Costs and profits will dictate this. Each structure may house an almost complete small city. Street congestion may be decreased by substituting more "vertical traffic" for horizontal, and by constructing arcaded sidewalks and three-decked or four-decked streets. A way out of the poor light and ventilation of city canyons is seen. "I think," says an export, ?'that there will be artificial atmospheric control in a few years that will astound us. A few engineers already predict artificial lighting more satisfactory than that which is brought in windows." fhf. ip^-*i>ite report says "buildings of seventy-five stories are not only economical, but under certain conditions ■will return more on the investment than a building of fifty or thirty stories." The seventy : five story estimate is based on land values of more than 200 'dollars (£4O) a square foot. The height .of seventy-five stories is calcudated to range from 880 to nearly 1000 feet. The report estimates the profits on eight imaginary skyscrapers, ranging from ten to seventy-five floors. It finds the highest net profit, 10.24 per cent, in a sixty-throe story building, the next best, 10.06 in seventy-five stories, 8.5 per cent, for a thirty-floor, and 4.22 for a ten-story building. The physical 150-story limit of twofifths of a mile is not due to lack of structural steel strength above that height. Too much weight would be required in elevator cables, says tho report, and the average human ear would not withstand tho vibration in an. elevator travelling at the speed required for service. This speed is estimated in excess of 1500 feet a .minute. Present elevator speeds are 750 to 800 feefc