Evacuation route planning for a nuclear emergency

This is a plan you make now, on a calm day, so that if officials call an evacuation you already know where you are going and how. It is not a plan to drive away right after a blast. Federal guidance says to shelter first and to evacuate only after officials have identified and cleared safe routes (FEMA Planning Guidance, sec. 3.5). See Should you evacuate or shelter? for that decision.

The planner above is an educational comparison, not a safety rating. It routes on a simplified map of interstates and US and state highways in the lower 48 states, between two ZIP codes, and steers around an illustrative planning area at each listed site used in the targets calculator. FEMA describes fallout settling downwind of a blast (FEMA Planning Guidance, sec. 1.5), so each area is a circle around the site plus a plume downwind. The sizes are the tool’s own settings, not FEMA numbers: a circle of 25, 50, or 100 miles, a plume three times that long reaching 20 degrees either side of the downwind direction, and a weight that counts each mile inside an area as 60 miles of driving. That weighting trades extra distance for fewer miles inside; it is not proven to find the fewest possible. Areas around your start or destination are shown but not avoided. The wind defaults to the usual west-to-east flow (see Step 4); change it to test other days. Google Maps, if you open the route there, plans its own route through a few points and does not know about the areas. The planner does not know local roads, traffic, damage, closures, or where fallout actually went. Official evacuation orders and real road conditions override anything it shows. The method below works without it.

Step 1: Know where the listed sites are

Start with the targets calculator. Enter your home ZIP and note the closest sites, how far each is, and which direction. Do the same for work, school, and any place your household spends a lot of time.

The list is a public-source estimate, not a war plan. It covers military sites from the Federation of American Scientists Nuclear Notebook and the 30 largest US metro areas. Real targeting plans are classified.

Step 2: Pick destinations before routes

Ready.gov says to “plan how you will leave and where you will go if you are advised to evacuate” and to identify several places you could go, such as a friend’s home in another town or a motel (Ready.gov, Evacuation).

Pick two or three, in different directions from home. A useful destination is:

• Somewhere you can stay for days. A relative or friend who has agreed in advance is better than a hotel you hope has rooms.
• Not next to another listed site. Run each candidate through the calculator. Fleeing one metro to arrive at the edge of another defeats the purpose.
• Not directly east of a listed site, when you have a choice. See Step 4.

Different directions matter because you will not know in advance which way is clear. FEMA notes that wind at different altitudes can carry fallout in more than one direction (FEMA Planning Guidance, sec. 1.5). A destination north and another south gives you an option either way.

Step 3: Plan routes that skirt listed sites

For each destination, trace a main route on a map. Then check how close it passes to each listed site. Routes that run through the center of a listed metro area, or past a listed base, are the ones to replace.

Why this matters on the road, not just on the map:

• Damage, debris, and stalled cars block roads near a blast. FEMA plans for crews to clear highways and evacuation corridors in damaged areas, and notes that “a considerable amount of roadblocking debris may be disabled or abandoned vehicles” (FEMA 72-Hour Guidance, Tactic 6).
• Roads out of a struck area will be crowded. FEMA tells officials to expect that “a large portion of the population will attempt to evacuate despite sheltering recommendations” (FEMA 72-Hour Guidance, Tactic 7).
• Fallout settles downwind of the blast. FEMA says the most dangerous fallout concentrations often occur within tens of miles downwind and typically fall within the first few hours (FEMA Planning Guidance, sec. 1.5).

A route that bends around a listed area adds miles. In a planning exercise, that is the point: you are trading distance for options.

Step 4: Factor in prevailing wind

Fallout drifts with the wind. Across the United States, the large-scale flow aloft runs west to east. NOAA says that within jet streams “the winds blow from west to east,” and that jet streams “typically move storms and other weather systems from west to east” (NOAA, The Jet Stream; NOAA NESDIS).

For planning, that gives you a tiebreaker. All else equal, prefer destinations and routes that are not directly east of a listed site, and prefer to start a route by heading away from a site’s east side rather than across it.

Treat this as a tendency, not a forecast:

• NOAA notes the jet stream “often shifts north and south” (NOAA), and NESDIS says its paths can change and take storms in unexpected directions (NESDIS).
• FEMA warns that wind direction and speed change with altitude, so fallout can be deposited in more than one direction, and that land-sea breezes can push winds aloft in the opposite direction from winds on the ground (FEMA Planning Guidance, sec. 1.5 and Appendix 1.2).
• Rain can bring fallout down in hot spots far from ground zero that are hard to predict (FEMA Planning Guidance, sec. 2.1).

On the day, the fallout map officials publish replaces the prevailing-wind guess. FEMA describes officials directing lateral evacuation, travel at right angles to the fallout path and away from its centerline, to minimize dose (FEMA Planning Guidance, sec. 3.5). If you have planned routes in more than one direction, you can match the one officials recommend.

Step 5: Plan an alternate for every route

Ready.gov says to be familiar with alternate routes and other means of transportation out of your area (Ready.gov, Evacuation). For each destination, pick a second route that does not share the same bridge, tunnel, or highway as the first. Bridges and tunnels are single points of failure: FEMA lists damage to roads, bridges, and tunnels among the access problems officials must plan around (FEMA Planning Guidance, sec. 3.5).

Step 6: Plan fuel and supplies

• Fuel. Ready.gov: “Keep a half tank of gas in it at all times in case of an unexpected need to evacuate,” and keep a full tank if an evacuation seems likely (Ready.gov, Evacuation). Check whether each route is within range of a half tank, since stations along the way may be closed or have long lines.
• Car kit. Ready.gov advises a portable emergency kit in the car (Ready.gov, Evacuation).
• Go bag. Ready.gov advises a go bag “with all the essentials you might need, so you don’t need to scramble in an evacuation situation” (Ready.gov, Evacuation). See the evacuation go bag list.
• Contamination. Ready.gov advises a spare change of clothes for each person and a trash bag for contaminated clothing (Ready.gov, Nuclear Explosion).

Step 7: Follow official instructions on the day

Your plan is a starting point. When an evacuation is called:

• Wait for the call. Ready.gov: “If advised to evacuate, listen for information about routes, shelters, and procedures” (Ready.gov, Nuclear Explosion).
• Use the official routes. Ready.gov: “Follow recommended evacuation routes. Do not take shortcuts, they may be blocked” (Ready.gov, Evacuation). If officials name a route that differs from yours, theirs wins. They know what is damaged and where the fallout is.
• Keep a radio on. Ready.gov advises listening to a battery-powered radio and following local evacuation instructions (Ready.gov, Evacuation).
• Do not go back early. Do not return until local authorities say it is safe (Ready.gov, Nuclear Explosion).

Your route plan, on paper

Write the plan down and keep a copy in the car and in each go bag, so it is there if phones or the internet are not.

Destinations

• Two or three places to stay, in different directions from home
• Each one checked in the targets calculator, not next to another listed site
• Hosts contacted and agreed in advance

Routes

• A main route to each destination that skirts listed sites
• An alternate to each that avoids the same bridges, tunnels, and highways
• Distances checked against half a tank of fuel
• Printed maps of each route

Ready to go

• Tank kept at least half full
• Car kit and go bags packed
• Battery or hand-crank radio for official instructions
• Household agrees: shelter first, leave when officials say

Next steps

• Decide when to leave and when to stay: Should you evacuate or shelter?
• What to pack: Evacuation go bag
• What to do before an evacuation is called: The first 72 hours