The reduction of an entire city to a pile of rubble poses a special problem for the survivors. Roads are blocked, underground pipes are broken, and disease accompanies the decay of incompletely buried bodies. Fresh water and sewage no longer flow, food becomes scarce, and the absence of shelter from extremes of temperature can make life miserable. In the cities of the ancient world a very real practical problem followed in the months and years after the destruction of a city—a cleanup operation beyond the wildest dreams of the survivors. Although steam shovels had been used for moving heavy materials in building the Suez and Panama canals in 1869 and 1910, respectively, it was not until 1923 that the bulldozer was invented. The even more useful backhoe followed 25 years later. Thus, clearing debris was a daunting task as recently as the 1906 San Francisco earthquake. In his book The City That Is: The Story of the Rebuilding of San Francisco in Three Years, Rufus Steele wrote of the rebuilding effort: . . . First the ground had to be cleared. The task would have baffled Hercules— cleaning out the Augean stables was the trick of a child compared to clearing for the new city. This is a step in the rebuilding which fails entirely to impress the visitor of today. He can form no conception of the waste which had to be reduced to bits and then lifted and carted away to the dumping grounds. The cost of removing it was more than twenty million dollars. . . . Lacking what we would now consider modern machinery to move large volumes of debris, the rebuilders of San Francisco extended railway lines across town, brought in steam and electric cranes, and relied heavily on teams of horses that suddenly found themselves in enormous demand. According to Steele, “Huge mechanical devices for shoveling and loading were invented and set to work.” Formidable as the task may have been, San Francisco tapped into several critical resources in its Herculean efforts: trains, cranes, and, perhaps most important, large numbers of survivors following an earthquake that killed a very small fraction of the local population.
Simulating the effects of redesigned street-scale built environments on access/egress pedestrian flows to metro stations
