To All: Someone in an earlier post mentioned the curb or lip on the sides of the road. These became very dangerous as semi tires, etc. would ride up on them causing jackknifing etc. There was a highway near my home in Independence, KS that had these and in the mid to late 50's the road was widened by digging a channel of the outside of each side of the road and then filling it in with a rock sub base and asphalt up to the height of the outside of the lip. Then the road itself was paved or filled up to the lip with asphalt also. Lastly a smooth top coat of asphalt was laid over the entire surface resulting in a smooth, wider road. In the ensuing years cracks would form down the middle, at each expansion joint on the underlying old cement road and along the edge where the new channel surfaces were laid. Then a crew would come back and fill the cracks with black tar. That is why there is a seam down the middle of the road and one about 2' in on each side. Derrick modeled this correctly on his road. Now you know.