Roads, too thin?

I always wondered why most of the roads are very thin prims, normally only 0.1 to 0.5 meters thick.
This causes that sometimes cars sink in the road themselves and remain stuck under them at some sim limits. Moreover i think it's the primary cause of the "bouncy" effect that cars seem to have on laggy places.
Wouldnt it be much better and more stable to build roads as thick concrete cubes sunk into the ground? I think giving roads some "foundations" would be a first step in making SL a driveable place.

Shiryu -

If you come across a place where you are sinking into the roads while zipping along, please post where and we'll have a look at the spot. Might just be the joiners aren't placed right (or at all, for whatever reason) and we can come rectify the situation.