If you need to evacuate everyone at once, sure. But they would evacuate gradually over many days from ~4 days to ~2 weeks from the attack, basically as soon as they will become desperate running out of drinkable water (something a house with a heater tank in the attic is also a good thing for).
No public infrastructure will work for that - bus drivers will quickly die of radiation sickness or just refuse to do their work, but for one, one-way trip to save your own ass it's okay.
Essentially, this is why suburbanisation come to being: war planners realized exactly the thing you are pointing out: that evacuating people in a crisis - while the Soviet bombers will be flying (it was before ICBMs) was an impractical idea, it will kill more people than it will save; but what works instead, is to evacuate people in advance: just make them live far from city centers which can be attacked. And redline the city centers: let only people you don't care about surviving, live there.
In 1950s Soviet Union, "workers and peasants" lived in villages and suburbs, these were replaceable anyway and killing them had little benefit. Difficult to replace cadres - engineers, most qualified workers, high ranking military, Party officials and such - lived in posh Stalinist apartments in city centers, and would perish inevitably. In 1950s U.S., it was already other way around. Soviet Union could do nothing about that: they simply couldn't afford an individual house, and thus inevitably, individual car, for everyone - they still can't. It was a clear win and moved a balance in the Cold War a great lot in U.S. favor.
One thing to realize here, it will best of all work if U.S. attacked first - then they choose the timing and attack in late evening in the U.S. when everyone is at home already, are warned, and don't leave their houses in the morning to avoid being caught in road panic, and have some hours to prepare for the Commie attack such as letting go of any combustibles, covering car so it doesn't suck fallout particles in, and stocking water and if possible, food.
Pripyat had 53,000 people evacuated by bus in one hour.
Hurricane evacuations even a week in advance are horrible by car. Highway infrastructure simply cannot cope with large movements of people in one direction.
No public infrastructure will work for that - bus drivers will quickly die of radiation sickness or just refuse to do their work, but for one, one-way trip to save your own ass it's okay.
Essentially, this is why suburbanisation come to being: war planners realized exactly the thing you are pointing out: that evacuating people in a crisis - while the Soviet bombers will be flying (it was before ICBMs) was an impractical idea, it will kill more people than it will save; but what works instead, is to evacuate people in advance: just make them live far from city centers which can be attacked. And redline the city centers: let only people you don't care about surviving, live there.
In 1950s Soviet Union, "workers and peasants" lived in villages and suburbs, these were replaceable anyway and killing them had little benefit. Difficult to replace cadres - engineers, most qualified workers, high ranking military, Party officials and such - lived in posh Stalinist apartments in city centers, and would perish inevitably. In 1950s U.S., it was already other way around. Soviet Union could do nothing about that: they simply couldn't afford an individual house, and thus inevitably, individual car, for everyone - they still can't. It was a clear win and moved a balance in the Cold War a great lot in U.S. favor.
One thing to realize here, it will best of all work if U.S. attacked first - then they choose the timing and attack in late evening in the U.S. when everyone is at home already, are warned, and don't leave their houses in the morning to avoid being caught in road panic, and have some hours to prepare for the Commie attack such as letting go of any combustibles, covering car so it doesn't suck fallout particles in, and stocking water and if possible, food.