This is the season of expensive do-overs for Philadelphia road projects, and drivers are paying in traffic snarls and detours, as well as added costs.

Near 30th Street Station, both the newly rehabbed JFK Boulevard bridge over the Schuylkill and the closed-for-reconstruction South Street bridge are getting unplanned additional work.

On the JFK bridge, workers have spent months tearing up a new sidewalk, blocking nine blocks of eastbound JFK Boulevard, and snarling traffic around 30th Street Station because decorative paint peeled off the new sidewalk.

Under the South Street bridge, workers are repairing new piers that cracked over the winter, apparently as the result of water freezing inside the columns.

The JFK bridge work is redoing part of a $17.9 million project million project completed last year by the Pennsylvania Department of Transportation to improve the vital link connecting West Philadelphia and Center City.

PennDot is paying $475,000 to a different contractor for a new pigmented sidewalk, while withholding $50,000 from the original contractor whose paint job failed.

The do-over, by contractor Buckley & Co. of Philadelphia, was required because "aesthetic paint treatment" to the concrete sidewalks peeled off. The original work was done by Driscoll Construction Co., of Spring House.

"The paint originally placed on top of the sidewalks to stain the concrete did not perform as intended; therefore, we are removing the previously applied paint and a top layer of concrete from the sidewalks and replacing it with pigmented concrete for a permanent fix," said PennDot spokesman Gene Blaum.

The work on the south side of the bridge and along the east side of Schuylkill Avenue between Market Street and JFK Boulevard started April 14, and PennDot said at the time it would last three weeks. By early May, the completion date had been pushed back to Memorial Day.

The "hydro-blasting" to rip off the top three inches of the new sidewalk took longer than expected, Blaum said, and a weeklong strike by construction workers also delayed the project.

The work is now expected to be finished by June 21, and once it is completed, crews will move to do similar work on the north sidewalk. That will take five to six more weeks.

But at least the traffic snarls will be over, since the north sidewalk work will not require detours, Blaum said.

On the South Street bridge, a $67 million project by Philadelphia's Streets Department, "there were some irregularities in the pour" of concrete to form the supporting piers, said Steve Buckley, the city's deputy commissioner of transportation.

The cracks were caused by water leaks into the piers.

Costs of the repairs will be borne by the contractor, Driscoll Construction, Buckley said.

The rebuilt South Street bridge, which crosses the Schuylkill, the Schuylkill Expressway, and Amtrak's railroad tracks, is scheduled to be reopened to traffic late this year. The repairs are not expected to delay the opening, Buckley said.

Contact staff writer Paul Nussbaum at 215-854-4587 or pnussbaum@phillynews.com.