Lyft, the popular app-based ride sharing service, is launching a pilot carpooling program aimed at commuters in San Francisco and Chicago, TechCrunch reports. After having success with its Lyft Line service, a ride sharing option that allows users to split rides with others, Lyft is now venturing into the world of mass transit with its new “Shuttle” offering.

Similar to the Lyft Line, the new shuttle feature will allow users to share rides with others, but the service will operate on set routes and have a fixed rate. According to TechCrunch, the service will not be affected by Lyft’s “Prime Time” pricing which increases fare prices during rush periods.

Similar to mass transit, the Shuttle service will operate with fixed pick-up and drop-off locations. According to The Verge, the service will only be able during rush hour periods in the morning and evening. No word yet on exact fares and routes, but The Verge suggests that Lyft is offering discounts to riders who use the service through April 30.