Civil engineers are spending countless millions of dollars and clear-cutting untold trees needlessly because they have forgotten one essential point of sustainable design: Roads and other infrastructure should sit very lightly on the land.
Left to their own devices, engineers will usually "mass-grade" a site, which means that they first cut every tree on the site. Next, they remove all of the topsoil, piling it in a huge mound somewhere. Next, they move many truckloads of dirt around all over the site, cutting some areas and filling other areas by a dozen feet or more on some sites. After they've put the storm sewers and other utilities in, they pave the roads and spread all the topsoil back out over the land. During this entire process, they must install erosion control all over to keep the soil from washing away. They go to all this expense in order to make the streets less humpy, so you're able to drive faster.
See the top picture? That's at a place called the Waters that I planned while I was a partner with PlaceMakers a decade ago. I had to fight tooth-and-nail with the engineer for weeks on end so he would sit the streets more lightly on the land. Engineering "best practices" say that you should fill in the dips and cut down the high spots along streets so that you have greater "sight distance." But wait… that's a stop sign at the intersection in the top picture. Once you get there, you can see further. You don't need to see all the way to the end of the road from the point where I took this picture. Fortunately, the civil engineer at the Waters was a good guy, and I was able to convert him to sitting more lightly.
One of the benefits was the fact that by not cutting and filling so much, we were able to preserve the majestic oaks along this avenue leading in to town. The trees grew up along a fence that had been built a century ago, and by saving them, it appears that the avenue might have been there that long as well. With normal engineering practices, they would have all been cut.
Here's another example at the Waters. When Nathan Norris and I first met the landowner, the land had already been planned by a conventional planner, but the landowner was having second thoughts about the plan. He pointed to a hill and said "where would you put all this dirt? The other planner said it won't work with his plan." I said "you mean the hill?" "Yes." "Leave the hill exactly where it is," I replied. "Line a street up with it, and build a chapel on the hill. We'll call it Chapel Hill." And so we did, as you can see.
I'm working right now with the Town Founder of one of the places where I'm Town Architect. He's about to build the next neighborhood in his town. The drawing above shows how the engineer has graded the first part of the new neighborhood. I'm not sure how accustomed you are to reading grading plans, but this land is mass-graded, so they'll have to cut every tree on the site and move many truckloads of dirt. Much of the land will be either cut or filled by 5-10 feet, and the really steep stuff on the right side will be filled by substantially more than that… think about fill taller than a two-story building in places!
Here's an alternative grading plan I did yesterday. My contours are all in red, so as you can see, most of the site is left untouched. The greatest amount of cut or fill on the alternative plan is four feet, but many areas that I've disturbed have less than a foot of cut or fill.
Taking this approach will likely save the Town Founder (and therefore the lot purchasers) over $300,000, and this is just one phase of one neighborhood of one new town. And the Town Founder gets to sell wooded lots instead of raw dirt. And the streets will cause people to drive slower, making them safer, especially for the kids and the old folks who walk there. Which would you rather have?
For almost all of human history, sitting lightly on the land was the only choice for most of us because moving dirt around was really hard work when you did it by shovel and wheelbarrow. Diesel-powered heavy equipment has given us the ability to push countless tons of dirt across the land, but should we do things just because we can?