To prevent a stampede for that single Greenfield train or an hysterical demolition derby on Memorial Drive. Forbes says local police will seal off the major routes leaving the city. "We want to reduce this as much as possible," says Forbes.

But when state and local planners presented the Cambridge proposal at last spring's hearing, the city council was completely unconvinced. Led by Saundra Graham and David A. Wylie, the councilors questioned the feasibility and propriety of civil defense measures, harping on the inevitable carnage expected after a nuclear attack, regardless of the sleep-over scheme in Greenfield.

The council concluded that "the sole means of protecting Cambridge citizens from nuclear warfare would be for nations with nuclear arms to destroy those arms and renounce their use." In an effort to increase public debate on the issue, the council prepared a booklet. Cambridge and Nuclear Weapons, and mailed it to 30,000 homes last summer. The 10-page pamphlet, packed with basic information on nuclear arms, exhorts Cantabrigians to "draw your own conclusion. Take action."

FEMA officials downplay the significance of the council's rejection. "The planning process will simply not take place in Cambridge." Clanahan says. He adds that only 11 of 3000 cities participating in preparations have opposed the planning. Forbes describes the Cambridge reaction as "a political move." Councilors, he adds, "are not going to sit around at ground zero or near ground zero and watch those things pop."

Regardless of their plans, however, civil defense officials acknowledge that without enough advance notice, "if a nuclear bomb hits anywhere where it's supposed to hit we're all dead," as Capt. Chester Hallice, director of the Cambridge Civil Defense Agency, puts it. FEMA officials are banking, therefore, on the expectation that Soviet leaders would try to evacuate their population before any nuclear attack on the United States, alerting analysts here to sound the alarms. "The Soviets only have blast shelters for 25 percent of their urban population." Clanahan explained, "they would lose 100 million people they did not have to with a pre-emptive strike."

"Civil defense is not military, it is a passive defense measure," Clanahan says. "If we had the capability to evacuate at least as quickly as the Soviets, civil defense might actually deter a nuclear attack by denying a disparity in vulnerability."

If warheads began falling tomorrow, Hallice remarks, the safest spot in the Northeast would be near the Canadian border, at a scenic retreat called Bear Lake. "But there are no shelters of any kind up there," he adds. "So if the fallout doesn't get you, the bears probably will."