CODLEIENE Exhaustive studies of the psychological and morale effects of working in windowless structures, tunnels, bank vaults, underground installations in Sweden, ete., indicate that no work decrement need be expected.* Estimates have been made of the comparative above-grade and undergroundinitial and operating costs for three types of installations: a precision manufacturing plant, a chemical plant, and a storage depot.” sites and utilizing existing mines. Consideration was given both to excavating new These costs, expressed as percentages of above-grade costs, appear in Table Bl. TABLE Bl CoMPARATIVE CONSTRUCTION AND OPERATING Costs FOR ABOVE-GRADE AND UNDERGROUND INSTALLATIONS (Expressed as percentages of above-grade costs) Costs and site Construction Above grade Existing mine New excavation Operating Above grade Existing mine New excavation Precision Chemical Storage 100 119 144 100 134 160 100 78 15] 100 102 103 100 104 106 100 98 99 plant plant depot It would appear that this type of hardening could providerelatively inexpensive protection. In at least many situations (where the undergroundinstallation is located near population centers, or where part of the factory is above grade), and given some warning time of the attack, an additional benefit would be that the undergroundinstallation could serve as a shelter area. | Another method of obtaining hardening would be to require that all new structures provide strength adequateto resist blast throughout a portion of their floor area, so that postattack emergency operations could be resumed or continued in a fraction of the floor space available prior to attack. Local building codes might be revised to require that 10 percent of the floor area of any new building within a metropolitan target zone be constructed to withstand some given peak blast overpressure, perhaps 30 psi or more. This 10 percent might be put underground, with a blastproof ceiling. Alternatively it might be a highly reinforced core of the building, with the outer and top portions of the building more fragile. If the entire building had a steel or reinforced-concrete frame the strengthened core would then be braced by the outrigger portions of the frame even though the walls and perhaps the floors of the outer portions were demolished. Although this requirement for a strengthened portion of each new building would not extend to provision of fallout protection, some building owners might want to combine a strengthened floor area with a shelter area. If blast and radiation protection equivalent to that provided under a federal underground shelter program were designed, federal shelter money might be included in the construction funds. This scheme,in fact, might provide the mechanism so long sought for obtaining dual-purpose shelter areas. Damage to buildings would also be lessened by general dispersal. In addition to the broad effects that could be achieved by planning a dispersed developmentdistrict, new zoning standards should be applied to the spacing of newbuildings in and around suburban nuclei. These standards might include a maximum percentage of lot occupancy (say, 90 ORO-R-17 (App B)