Yeah, in the Czech Republic (or especially the former Czechoslovakia), part of the main D1 highway (Prague-Brno) is designed as an alternate airfield.

Here is a (then-classified) 1980 army documentary about a large exercise on the highway (using MiG-21 and MiG-23 planes): https://www.youtube.com/watch?v=FDoZGoaG9_w (sorry, Czech only)