Wow, very resourceful! 
The roads are different depending on each map.
In Fueldump the road is a decal placed onto the terrain. The decal is made from patches and carefully lined up with the terrain triangles. The second road going up to the tank bay was the hardest to create because of all the various angles from the terrain. The inside of the tunnel is mostly brushwork nicely twisted into place with very few overlaps. (The middle section of the tunnel is patches so you get nice sweeping corners.)
In radar the road leading from the bridge to the main door is all patches (usually the 9x3 variety) with the bump side sections tacked on. These sections are sort of lined up with the terrain triangles with a few gaps here and there. The inner courtyard of the axis base is a combination of brushwork and patches for the edges of the roads. Took a fair amount of time due to the complex nature of the road moving down to the main building and then carry on to the garage area.
A good example of the patch road system is in the map for RTCW called mp_base. (Which was accidently given away in the main pk3 file for RTCW) It shows the road made from 3 sections of patches nicely stitched together.
Sock
:moo: