CONFLDENMAE one-fourth the foxhole device discussed subsequently (for cities where mass evacuation is proven feasible). Such a mix, after allowing for the day-night ebb and flow, would cost $24 billion for the 25 cities and $33 billion for the 170. Many other combinations are possible, and a shelter program should be undertaken only after careful consideration of local needs. Subways, modified so as to permit quick entry and so as to permit closing entryways, not only provide good shelter but can provide protected movement away from the target area. Theinitial cost of subway systems would be greater than that for other types of shelters, but might well be offset by operating revenue. Fig. 46 — Family Outdoor Shelter Improvised Shelter Should Congress and the public remain apathetic to shelter programs, the Engineer Research and Development Laboratory, Ft Belvoir, has in prototype stage a device that could be adapted to civil defense needs with relatively little difficulty, according to the de- signer. This device (Fig. 47) was originally developed for digging foxholes quickly to protect 64 ORO-R~17 (App B) CONFTOEO-ELAL