Hide Under an Underpass in Tornadoes (Safety Myth)
Do not shelter beneath, on, or beside an overpass or underpass during a tornado. It offers no reliable protection from wind or flying debris and may expose you to traffic, water, or entrapment. Go instead to a designated storm shelter or a sturdy building’s lowest-level interior room. Plan the route and backup shelter before severe weather begins.
A low-profile, well-planned shelter is safer than relying on a familiar structure that looks solid. If you prefer eco-conscious choices, prepare reusable supplies, such as a refillable water bottle and rechargeable light, but never let a smaller footprint compromise safety. The key is to know where you will go and how you will get there before a warning is issued.
Planning: Reject the Underpass; Select a Real Shelter
A tornado shelter is a place designed or chosen to reduce exposure to wind and debris. An ordinary underpass is not a designated shelter. NOAA and the National Weather Service advise against using overpasses for tornado protection; plan to shelter in a purpose-built safe room or a sturdy building’s lowest-level interior room.
Why an underpass is not a safe place
An overpass or underpass is part of a road system, not a tornado shelter. Its concrete may look protective, but appearance alone says nothing about its resistance to tornado winds or flying debris. Wind can move forcefully around and beneath a bridge, while vehicles and debris can strike people who are exposed there.
The structure may also create escape problems. Traffic can continue moving, roads may become blocked, and heavy rain can cause water to collect or flow through low areas. A person who reaches an underpass may have no safe way to leave if conditions worsen.
Do not shelter under, on, or beside an overpass or underpass. Do not stop a vehicle there to wait out a tornado.
Choose your primary and backup shelter
Select a designated community shelter or a sturdy building before severe weather. At home or work, the usual choice is a basement or a small, windowless interior room on the lowest floor. A hallway, closet, or bathroom may work if it is away from windows and has a clear route, but no ordinary room should be described as tornado-rated unless it meets the applicable safe-room design and construction requirements.
Check for flood risk before choosing a basement. If flooding is possible, follow local emergency-management advice and choose a safer location. Identify a backup shelter in case your first choice is locked, too far away, or inaccessible. Do not make an underpass the backup.
- Write down the shelter address and route.
- Check whether the shelter is open and accessible when you might need it.
- Tell household members or staff where to go.
- Follow local emergency alerts and instructions.
Access and Clearances: Use Shelter Criteria, Not Bridge Geometry
A useful shelter plan accounts for people, access, and local hazards. It does not rely on the size or shape of a bridge. FEMA guidance uses 5 square feet of usable floor area per person as a planning allowance for residential safe rooms; this is not a substitute for engineered design or local code requirements.
Plan space and a clear route
The 5-square-foot figure helps estimate space for occupants in a residential safe room. For example, four people would need 20 square feet of usable floor area under that planning allowance. The actual design may require more space, and the allowance does not prove that a room can withstand a tornado.
Keep the route to your shelter clear, including the entrance and door swing. Avoid storing items where they could block access. If someone in the household needs extra time or mobility support, plan for that before a warning, not after one begins.
For a purpose-built safe room, a qualified designer should determine the site-specific design wind speed, exposure, debris protection, anchorage, and applicable building-code requirements. ICC 500-2020 and FEMA P-361 (2021) provide guidance for safe-room design and construction. A bridge’s shape, concrete surface, or sheltered appearance is not a substitute for those criteria.
| Situation | Safer plan | Do not rely on |
|---|---|---|
| At home, with a basement and no known flood concern | Go to the basement, away from windows | A garage, porch, or underpass |
| In a sturdy building without a basement | Use a small, windowless room on the lowest floor | A room with large windows |
| In a mobile home | Leave well before the storm for a sturdy building or designated shelter | The mobile home or an overpass |
| Driving when a tornado threat is near | Follow official local guidance and reach a sturdy shelter early | Stopping under a bridge |
Execution: Shelter in a Building, Not Beneath an Overpass
A workable plan has four stages: survey the location, prepare people and supplies, build only to an accepted safe-room design if needed, and verify the finished space. These steps help prevent last-minute choices. They also make clear that an ordinary underpass is not part of the shelter plan.
Stage 1: Survey and select the room
Identify a basement or a small, windowless interior room on the lowest floor of a sturdy building. Check for flood risk, windows, and a clear path from the areas where people spend time. Choose the shelter that occupants can reach in time, and confirm a backup location.
Illustrative planning scenario: A household’s first choice is a basement, but the basement has a known flood concern. The family checks local guidance and identifies a suitable interior room or nearby designated shelter instead. This is a planning example, not a report of a specific household or tornado event.
Stage 2: Prepare people and supplies
Keep shoes, essential supplies, and a way to receive official alerts where they can be reached quickly. A weather radio can help when power or mobile service is disrupted. Include pets in the plan and decide how they will be moved to shelter. Use supplies that fit your needs; preparedness does not depend on buying a large set of new products.
If you live in a mobile home, plan to leave for a sturdy building or designated shelter well before a storm arrives. Do not wait until a tornado is close, and do not drive to an overpass for cover. Follow local emergency-management instructions about where to go and when.
Stage 3: Build only to a safe-room design
A safe room is a space designed and built to meet applicable requirements for protection from severe wind and debris. If you need one, work with a qualified designer and use engineered plans and tested assemblies that meet ICC 500 and applicable adopted codes. Do not assume ordinary framing, a reinforced-looking door, or a DIY retrofit makes a room tornado-rated.
Stage 4: Verify the finished room
Where required, confirm that permits and inspections are complete. Check that the door operates as designed, the route stays clear, and the finished room matches the approved plans. If the room is altered later, seek qualified advice before relying on it. Do not label an underpass or an unverified room as a tornado shelter.
Verification: Edge Cases and Exclusions
A shelter plan is only useful if it is safe to reach and fits the building and local hazards. Check the route, access, flood risk, and official instructions. When conditions are uncertain, do not improvise with a bridge or claim that an ordinary room meets a safe-room standard.
If you are already near an underpass
Do not enter or stop beneath it for tornado protection. Move toward a sturdy building or a designated shelter if you can do so safely and in time. If you are driving, use official local guidance and avoid creating a traffic hazard. There is no single safe action for every road or storm situation, so follow emergency-management instructions for your area.
Illustrative planning scenario: A driver sees an underpass ahead as a warning arrives. A better plan would have identified a sturdy shelter along the route before the trip. This example shows why route planning matters; it is not a claim about a specific incident.
If no purpose-built shelter is available
Use the best suitable space in a sturdy building: a basement or a small, windowless interior room on the lowest floor. Stay away from windows and follow local alerts. A safe-room label should be used only when the room has been designed and built to the relevant standard. Do not treat an underpass as the fallback.
Key next steps
- Pick a primary shelter and a backup now.
- Confirm the route, access, and any flood concerns.
- Prepare people, pets, and basic supplies.
- For a built safe room, use qualified design, applicable codes, and required inspections.
Frequently Asked Questions
Is it safe to hide under an overpass during a tornado?
No. An overpass does not provide reliable tornado protection. Windborne debris, traffic, water, and limited escape routes can create serious hazards.
Is an underpass safer than staying in a car?
Do not use an underpass as shelter or stop a vehicle there. Follow local emergency guidance and plan to reach a sturdy building or designated shelter before the storm arrives.
Where should I go instead?
Go to a designated storm shelter or a sturdy building’s basement or small, windowless interior room on the lowest floor. Consider flood risk and follow local instructions.
What if I have no basement?
Use a small, windowless interior room on the lowest floor of a sturdy building. Stay away from windows and keep the path clear.
Should I use a basement if it may flood?
Do not ignore flood risk. Check local emergency guidance and choose a safer available shelter location if the basement may flood.
How much space should a residential safe room provide?
FEMA guidance uses 5 square feet of usable floor area per person as a planning allowance for residential safe rooms. It does not confirm that a room is safely designed or built.
Can I make a regular room tornado-rated with a strong door?
Not by guesswork. A purpose-built safe room must follow applicable design and construction requirements, such as ICC 500 and adopted local codes.
What should someone in a mobile home do?
Leave well before the storm for a sturdy building or designated shelter. A mobile home is not a safe place to ride out a tornado.
Should I shelter under a bridge if I am driving?
No. Do not stop under, on, or beside an overpass or underpass. Use official local guidance and seek a suitable shelter in time.
Which guidance should I check?
Follow local emergency-management instructions and National Weather Service guidance. For a purpose-built safe room, consult a qualified designer familiar with ICC 500-2020, FEMA P-361 (2021), and applicable local requirements.
(This article was written by one of our staff writers, Richard Montclair. Visit our Meet the Team page.)
