Straight roads have little to do with driver speed. It’s how you design the roads. Wide lanes with buildings set back from the road? Higher speeds. That’s why some initiatives put curbs that jut out into the road (not into the lanes of travel) with trees and plants and such, and remove road striping. Combine pedestrians and road traffic on a road that looks more like a parking lot and you get drivers driving slowly. Sounds counter-intuitive, but it works.