Walkable City: How Downtown Can Save America, One Step at a Time

by Jeff Speck

First: The computer model is only as good as its inputs, and there’s nothing easier than tweaking the inputs to get the outcome you want. When we were working in Oklahoma City, the local traffic engineer’s “Synchro” computer model said that our pro-pedestrian proposals would cause gridlock. So we borrowed that engineer’s computer model and handed it to our engineer, who tweaked the inputs, and voila: smooth sailing. By the way, the most commonly tweaked input is anticipated background growth, which typically needs tweaking anyway: most cities’ traffic models presume 1 to 2 percent annual growth, even when those cities are shrinking.