San Francisco has the advantage in having many ports. These could be used to trade, evacuate to San Francisco, or should the worst happen, evacuate from San Francisco onto either an island (Treasure Island, Angel Island, or other, smaller islands.
San Francisco has a couple of paths they can choose; they can go the minimalist route, which would be cramped. They should evacuate people from the zone immediately outside their borders (which could end at the SF Airport, along Rt. 92) and move them northwards, towards the City proper. They should make preparations to house their current population many times over, as people may flee zombie hoards coming from the Mid-west or south, which is most likely considering population densities. This would be a worst-case scenario for the Bay Area. If the infection is coming down from the North, then securing the bridge while additional resources, walls, barricades, or other preparations are made would be an easy task.
If the additional population becomes a burden, San Francisco could launch a major, manpower-intensive (on the backs of the refugees to your city, if necessary) effort to clear the towns below.
The danger of the minimalist approach is that the smaller your square mileage, the less breathing room you have for error. By moving south, you gain additional ports, more manufacturing area, another airport, and more breathing room in general. By overextending yourself, you draw power away from ports, manufacturing, etc. and have a larger border, and therefore a larger drain on your resources. The parks and reserves to your west would prove to be serious threats to the safety of San Francisco city. Even at the most minimalist approach as to “livable” areas, the forest would be an obstacle to your safety. Perhaps if you were to draw resources from the area or establish a kill-zone and put in sniping positions/sniping towers, it would be theoretically possible to establish a Maginot line through the forests, using a small, two lane road or service road.
The middle-expansion to Palo Alto/Mountain View would help provide additional airports again, as well as breathing space and an additional bridge if necessary, with which one could take in more survivors.
A major expansion, and the maximum size I’d recommend would be San Jose or Sunnyvale, cutting along Rt. 17. A trading port/allied city outpost in Santa Cruz be established between there and Los Gatos, with a spine between the two cities along SR 17, which could serve as a patrol line for troops. The further south one goes (until they reach the end of the forest), the wider the hole in the defenses. This is the widest point, admittedly, but it also has the most clear definition of boundary, and with Santa Cruz on the other end, it would allow for reinforcements to come from either side, to pinch off any breakthroughs in the line. So much energy would be expended in a day just by patrolling such a large, yet unclear boundary frontier that it would consume resources and food supply rapidly, but with the territorial gains might also come gains in food production, especially in fishing from Santa Cruz.
The SR17 line is a long line, but the gains for San Francisco would be immense, as it would allow them full access to their forests, close a major gap in the defenses, add airports, population size, shut down cesspools. Outposts/towers could be constructed further southeast, to thin out any hoards, as I’m under no illusion as to how thin the line would have to be spread. Any two breaks in the line would encircle your border guards. SR 1 would then be used as a trading spine only, with no personal travel allowed.
As seen in “After People,” pools will become cesspools for disease to spread, particularly mosquitoes. Life might get pretty miserable, but it’s better than being a zombie, if only barely as medicinal supplies dwindle. Trade will be the best bet San Francisco has to gain more from raiders who hit areas up and down the coast for medicine and then return to San Francisco. The more areas under San Francisco’s control, the less disease would take hold.
Unfortunately, not all of the Bay Area would be so fortunate. San Francisco’s eastern border is pressed against the water, and there are far too few ships in the area to take everyone. Traffic would reach unbelievable levels. A single car breaking down on a bridge would cause a complete shutdown. The bridge, however, can only accommodate so many at a time, even with traffic not flowing and people walking between the cars, the bridge itself would only then allow for the passage of six more “rows” of people to pass, and even then, slowly.
The bottleneck would create nightmarish conditions. Stampedes, trampling, suicide, and even riots, or people running amok, would certainly not be out of the question, and should even be considered likely.
With such a drain on population, any attempt to hold the line in Oakland, Hayward, Newark, and Fremont would fail. The Golden Gate Bridge would have the same issue as the Bay Bridge; therefore, the drain would be equal. Nobody will run to Oakland, Newark, Hayward or Fremont, but the city will be drained. People may try to run from San Francisco, but as many people will try to flee from there, an equal number of people will be attempting to flee *to* there as well. It would be a zero-pressure system.
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