Do you ever think about the ecology of the city you live in? Not just the parks and the smog. Scientists are starting to examine urban ecosystems more holistically: the trees and the concrete, natural gas lines and soil, water pipes and rivers. The natural and the synthetic feed off each other in surprising ways. We’re not scientists, but we found it interesting.

Then we move from the ecosystem to the highway system — specifically, the argument made by Evan Jenkins in The Week to abolish the National Highway System. Chuck Marohn at Strong Towns thinks it’s a good idea. Jeff and I aren’t so sure. Could rail really pick up the slack? Would states make better decisions? What funding source would replace the federal gas tax?

Enjoy this, our 42nd episode of Talking Headways. Find us on the Twitters already. And oh yeah, also on iTunes, Stitcher, and the RSS feed.