CHICAGO (AP) — Legislation that allows a suburban Chicago bus agency’s vehicles to ride on the shoulders of a major roadway is now law.

Gov. Pat Quinn signed a plan on Monday that makes Pace’s “Bus on Shoulders” pilot program permanent. Pace bus drivers on two routes that travel on Interstate 55 are able to use shoulders as a passing lane when traffic is moving slower than 35 mph. They’re not allowed to travel more than 15 mph over the top speed of vehicles in the expressway lanes.