CRANBERRY TWP — Crews are paving Interstate 79 south of Zelienople, work that is causing residual backups on Route 19.

The miles-long backups started about 5 p.m. Monday and continued Tuesday, being particularly heavy during the afternoon rush hour as drivers try to circumvent the project.

Deborah Casadei, spokesman for the state Department of Transportation, said Tuesday that the I-79 paving likely will last until October. It affects the portion of the road between Route 528 in Jackson Township and Cranberry Township.

Casadei called it a “fairly significant” project that could cause residual delays for weeks.

“We’re asking drivers to slow down, pay attention to the signs and merge appropriately,” she said. “That will go a long way to making traffic flow a lot better.”

Township manager Jerry Andree said Tuesday that officials will change traffic signal patterns in an effort to alleviate the congestion.

“We’re trying to move it through quicker,” he said.

Andree added that PennDOT didn’t alert local officials about the work, and that officials at first didn’t know why traffic had backed up on Route 19.

Andree added that the township will send out a notice to residents telling them the cause of the tie-ups.