CHICAGO (CBS) – More Pace buses will be riding the shoulders of I-55 by next summer — and could possibly be taking riders between the Loop and southwest suburbs middays, and on specials to White Sox and Bears games.

Calling the pilot project an “outstanding success,” members of the Regional Transportation Authority (RTA) board extended its commitment to the pilot project from two years to five years Wednesday, agreeing to finance maintenance, snow removal and the removal of debris by IDOT from the shoulders used by the buses at a cost of up to $500,000 a year beginning in late 2014.

IDOT and a federal grant are financing those costs until then.

In addition, it voted to extend the shoulder-riding eastward to a half-mile east of Ashland Avenue, almost to the Dan Ryan Expressway.

RTA Deputy Executive Director Leanne Redden said that ridership since the pilot project began has more than doubled on its 755/Plainfield-Illinois Medical District Express and on its 855/Plainfield-East Loop Express, which terminates on the Magnificent Mile.

Redden said on-time performance on the two routes has improved by 20 percent despite faster schedules, and said Illinois State Police report no accidents and minimal reports of cars trying to follow the buses, which are specifically exempted from a statewide ban on shoulder-riding.

Expansion of the service could begin as soon as June 15, said Pace spokesman Patrick Wilmot, and could include reverse commute trips to the southwestern suburbs.

All restrictions on hours of operation or direction are being removed. For the first year, the buses have been limited to inbound during the morning rush period and outbound during the afternoon rush.

The service is so successful that Pace has ordered 15 new over-the-road buses, designed for long-distance operation, with plush seats and luggage racks, to supplement the eight buses already used in the I-55 corridor service.

Wilmot said Pace officials believe a market exists for express service to U.S. Cellular Field for White Sox home games and to Soldier Field for Bears games. The expanded operation allows for such service.

The expanded shoulder-riding closer into the Loop is expected to result in even faster schedules. Wilmot said the section between Kedzie and the Ryan is among the most congested that Pace faces each weekday, and is often backed up outside of rush hours.

Aside from the IDOT maintenance costs, Wilmot said the additional costs to Pace would be minimal, just drivers and fuel.

Pace is seeking to include bus-only or high-occupancy vehicle lanes during the next reconstruction of both I-55 and I-90.