That WS Smooth-It is junk. It's wayy too thick, as Ken said, hard to spread to get a smooth layer, and dries with all kinds of cracks and uneven spots no matter how you apply it. I can't think of a worse material for roads.
For concrete rods, you just can't beat thin styrene, .010 .020 thick. It's easy to cut to shape, easy to glue down with latex caulk, and can be painted and weathered very realistically. Floquil Aged Concrete paint is a good start. You then uses chalks for oil stain in travel lanes and a fine tip black marker for expansion joints and tar lines. It will take you a little practice but it's not a hard teqnique to master.
This whole concrete highway was created using the methods I described and I think it looks like a pretty good representation of a concrete road:
For concrete rods, you just can't beat thin styrene, .010 .020 thick. It's easy to cut to shape, easy to glue down with latex caulk, and can be painted and weathered very realistically. Floquil Aged Concrete paint is a good start. You then uses chalks for oil stain in travel lanes and a fine tip black marker for expansion joints and tar lines. It will take you a little practice but it's not a hard teqnique to master.
This whole concrete highway was created using the methods I described and I think it looks like a pretty good representation of a concrete road:
