Houston is usually measured in terms of building height, occupancy rates and freeway systems. But a growing number of green-minded (and literally groundbreaking) innovators are working to change that. Now the numbers on everyone’s lips involve the city’s bayous — specifically, 150 continuous miles of hiking and biking trails geared at getting Houstonians out of their cars and back to nature. The Houston Parks Board’s signature project, Bayou Greenways 2020, starts construction this month on a section of Brays Bayou Greenway that meanders from the Ship Channel to Old Spanish Trail, with many more pathways to follow. Itching to hit the pavement sooner? Another major project, Buffalo Bayou Park — Shepherd to Sabine, rolls out a series of trails funded by the Texas Department of Transportation this summer, including the 4.5-mile Sandy Reed Memorial concrete trail, which loops from Shepherd to Sabine. Also changing the hike-and-bike landscape are the Jackson Hill and Police Memorial bridges, both opening to the public in early fall as part of the Buffalo Bayou Park Partnership’s $58 million project. And that’s only the beginning. Over the next few years, look for kayak and bike rentals, more benches, a picnic pavilion, artful lighting and the reintroduction of native plants and landscaping. Does all this sound revolutionary for our famously urban environment? Think again: The idea of a park system integrated with the city’s bayous was first proposed way back in 1912. buffalobayouparks.org; houstonparksboard.org.