Road Pavement Variations
 

Today I was driving from Knoxville TN to Statesville, NC on I-40 and as I was coming through the mountains I kept noticing that even on better than average down hill grade my scan gauge was giving some terrible readings. After I got through the mountains I noticed the readings were higher on uphill grades than they were on down hill grade in the mountains. I got to trying to figure out what the difference could be and noticed I was running on a concrete paved road when the mileage was good and running on asphalt when I was getting the low numbers. Concrete is smoother with the exception of the expansion joints so I guess the rolling resistance must be much lower on concrete paved roads than on asphalt. Just another piece of information that I thought might interest some of the readers. So if you have two routes somewhere and the distance is about the same check to see if the roads are different surfaces it might just save you some money.

I noticed that too but it was easier for me to see. I was on a relatively level state road parts of which were paved at different times. The mileage went down as road noise went up.

I drive that road all the time, Ford Man. Your results are actually shocking to me. I know that in and around Hickory the road is in very poor upkeep. There are tons of potholes and patches, even though it is concrete.

The fun part of the ride is EOCing over the eastern continental divide down through Old Fort. I end up doing 80 by the time I get to the bottom of the hill. haha.

I drove through a construction zone this morning where the first base layer of pavement has been laid. It is perfect with no cracks or anything, and it looks/sounds/feels smooth, but my car was losing speed going down a slight grade where it should have gained a little speed.

Maybe a little sticky still.

I know exactly where you are talking about I coasted down the mountain with the engine running in neutral and was see about 350mpg on my scan gauge. I have found that about 80 is all I can handle on some of those curves so I had to brake several times in order to maintain an 80mph "safe speed". There is no doubt in my mind that you could exceed 100mph coasting down that mountain if you could hold it on the curves. When I drove through the mountains near the TN state line where the pavement was asphalt, even though there are some pretty steep grades if I tried to neutral cost I would lose speed instead of gaining. The car was accelerating down those mountains with the cruise set at 55 and the scan gauge was only reading 25-30mpg in the Escort Wagon.

if its hot the asphalt does get tacky (ever ride a bicycle over those tar patch strips and sink in?)

concrete is always hard, there sa section in town where they cut grooves parallel to the edge of the road, with my skinny tires on the chevette the grooves act like rails to a train, it just kinda wobbles side to side :D)