Hi Sean, and you are probably aware that you outlined a ready made
and somewhat simple research project. We know if a road is asphalt or
concrete and we have thousands of roads to be able to test.

One of my claims for asphalt is that it is a soil conditioner since it
is acidic and would improve a alkaline soil pH. Correct me if I am
wrong but I suspect most every concrete is alkaline due to the lime
added to concrete but whether road concrete has lime added is unknown
to me.

Anyway it would be an easy and exciting, mostly exciting, science
research project to see what plants thrive next to asphalt roads
compared to concrete roads and to find out whether my claim of soil
conditioning by asphalt improves alkaline pH soils such as here in
South Dakota. One of the reasons that my raspberries love the tar roof
shingles as a mulch is my hunch that the tar adds acidity to the soil.
So if plants on the East Coast with their acid soils should do less
well if asphalt roads are nearby than if concrete roads are nearby and
here in South Dakota plants would do better near asphalt than near
concrete. Provided of course that asphalt and concrete contribute to
the soil pH.

Archimedes Plutonium
www.iw.net/~a_plutonium
whole entire Universe is just one big atom
where dots of the electron-dot-cloud are galaxies