(CBS) — Pace has decided to “go slow” with plans to increase the number of buses riding the shoulder on I-55.

The suburban bus agency remains committed to the changes. But spokesman Patrick Wilmot said Wednesday that a pair of factors could delay implementation of the changes for between one and three months.

Approval had been expected at Wednesday’s monthly Pace board meeting, which a start date of Aug. 17 or 18.

Wilmot cited ongoing construction work on the I-55 median strip to allow buses to use the shoulder in more areas, particularly east of Kedzie Avenue on the Stevenson Expressway. And he said Pace hopes to do more outreach to explain the changes, particularly those affecting current 855/Plainfield-East Loop Express line.

Pace plans to add service to the 755 route, which links Plainfield with the Medical Center district and Chicago Union Station. Plans for the 855 route call for it to be split into three lines, to speed up the service and minimize confusion for homebound riders.

Wilmot said the new 850 route would stop inbound and outbound at the Canterbury Park ‘n Ride in Bolingbrook. The new 851 route would serve the Old Chicago Park ‘n Ride in Bolingbrook and Romeoville. The shortened 855 route would serve Plainfield and Burr Ridge.

Wilmot said ridership continues to increase on it shoulder-riding buses. He said ridership on the 755 line has more than quadrupled, and 855 patronage has nearly doubled, since November 2011, when shoulder-riding began. But he said the current skip-stop 855 schedules have confused some homebound riders.

Wilmot said schedules to virtually all stops on the four routes would be faster as a result.

Pace and the Illinois Toll Highway Authority also are planning for upcoming construction along the Jane Addams Tollway. The Pace board Wednesday is expected to approve construction of several Park ‘n Ride lots. Wilmot said they are expected to be ready when the full extent of the I-90 reconstruction gets underway in 2016.