Kevin Brooks
Some European nations (especially Sweden) did indeed design roadways
to handle dispersed aircraft operations, but that was aimed primarily
at tactical fighters.

Indeed. And most (all?) the Swedish jet fighters. An example of
adoption for road bases is the unusual thurst-reversal engine
exhaust of Viggen, which dramatically cuts the lenght of the
landing run.

In Finland too, the airforce planned (and still does) to operate
dispersed from highway bases in war. There are also sections of
highways specifically designed as bases, being wide, straight
and with a runway profile and markings. While not designed for
road bases, the fact that the current F-18's of the FAF are
carrier planes, is helpful. For example, they do arrested
landings on prepared highway strips.

Some Soviet tac fighters, too, are well adapted for operations
from improvized bases, even unpaved runways. MiG-29 being a good
example: STOL, tough undercarriage and unusual alternative air
intakes for take-off and landing for avoiding FOD.

What really surprizes me, is that the US tac fighters of
the cold war era stationed in Europe didn't, as far as
I know, plan for dispersed operatons. Did they really think
that their bases would survive in the 'big' war? And,
consequently, the planes weren't (aren't) that well suited
for such operations either (eg F-16, although I think that
Norway operates its Vipers from road bases too).