For decades, Jim Starry has envisioned airports that were designed to facilitate fuel efficiency and less carbon emissions. He believes that "if we took a different approach to orientation, layout, and land use, airport design could facilitate profound improvements in everything from fuel efficiency to public health."
Starry's "different approach" includes inclined runways and gates on top of a hill. Terminals and parking would be underneath the hill. The planes would have less distance to taxi between gates and the runways, and gravity would help them increase their airspeed during take-off and landing.
As Sarah Rich explains, implementing Starry's ideas into airports is difficult because his plans require a complete reconstruction of the airport. Most airport construction is limited to terminals or additions--not the entire airport. Aviation experts are also concerned about "questions of safety, construction costs, and potentially suboptimal outcomes for travellers (such as driving several miles through enclosed corridors beneath the runways to reach the terminal)." Given these considerations, Starry's innovative "Starports" have yet to be seen in real life.