A new initiative from Sidewalk Labs, the city-building subsidiary of Google's parent company Alphabet, has set out to change that.

The program, known as Replica, offers planning agencies the ability to model an entire city's patterns of movement. Like "SimCity," Replica's "user-friendly" tool deploys statistical simulations to give a comprehensive view of how, when, and where people travel in urban areas. It's an appealing prospect for planners making critical decisions about transportation and land use. In recent months, transportation authorities in Kansas City, Portland, and the Chicago area have signed up to glean its insights. The only catch: They're not completely sure where the data is coming from.

Typical urban planners rely on processes like surveys and trip counters that are often time-consuming, labor-intensive, and outdated. Replica, instead, uses real-time mobile location data. As Nick Bowden of Sidewalk Labs has explained, "Replica provides a full set of baseline travel measures that are very difficult to gather and maintain today, including the total number of people on a highway or local street network, what mode they're using (car, transit, bike, or foot), and their trip purpose (commuting to work, going shopping, heading to school)."