I love this map, and its confirmed that's it takes place in the survivors journey between Blackfield and new bloxcoast. here's the idea,
Step1. repair the bus! loot other buses around the map and bring wheels, gas, and engines back to your bus, each item is takes up your hands, equip = drop each bus has one of the parts so you only need to loot 3.
Step2. get supplies! go around the map and find crates, bring them to the roof (need 6) they all spawn next to each other
Step3.get armor! go into one of the buildings to find armor for the bus, the tunnel you escape through is blocked and will destroy your bus if you ram into it, armor is necessary! go to the front of the bus and apply it (armor looks like metal sheets in hands and looks like rusty metal plates on the front of the bus, then in 15 seconds the bus will move back ten studs and rapidly speed up forwards into the blockade and cars through it, thus escaping, the campaign gives 250 with minimal players, and 900 with a full server. btw the bus moves forward like 100 studs every step.
If you want, I have more campaign ideas for rescue maps!