In Texas, they implement "hurricane lanes," which just means during disasters, you can legally drive on the shoulder. In practice, I've seen it where all lanes are made outbound-only.

If you live within 10 miles of a US Nuclear Facility like me, NRC requires they send an annual calendar marked with siren-testing dates and escape-route maps. You can request free iodine tablets, for use while you're irradiated in traffic.

But IMHO both examples are mostly just coping mechanisms, designed to give panic direction.