Updated 12/5/14 – 9:24 a.m.

CHICAGO (CBS) — State officials on Friday tried to deflect blame for a major traffic jam on the inbound Kennedy Expressway, while apologizing to commuters for any inconvenience when two lanes were shut down to clean graffiti from a highway sign at Division Street.

It was not immediately clear who sprayed the graffiti on the large green sign indicating which lanes of the Kennedy merged into the southbound Dan Ryan to Indiana, but the Illinois Department of Transportation said the graffiti was being removed during rush hour to make sure drivers could read the sign.

“We were alerted right before the start of the morning rush that there was graffiti obscuring an important sign approaching downtown Chicago on the Kennedy Expressway. People do rely on the sign to get to where they need to be going,” IDOT spokesman Guy Tridgell said. “The situation certainly wasn’t one of our doing, but we made the decision to address it as quickly as possible.”

The crew that was removing the graffiti around 7 a.m. had pulled off the road by 7:40 a.m., but by then, travel times on the inbound Kennedy had skyrocketed. At the time, the travel time from O’Hare to downtown was nearly two hours; from Montrose to downtown it was 1 hour 15 minutes; and in the express lanes, it was 1 hour.

Garo Sazian was one of many travelers who was caught in the traffic jam, and he said he was going to be late to work as a result.

“They cannot do it at night? … The lanes are open, there’s no traffic, they can put up huge lights, and they can do whatever they want to do. Not in the morning,” he said.

Tridgell, however, said IDOT decided the graffiti needed to be removed right away, because of how important the sign is to commuters, and the graffiti had obscured the text on the sign.

“We removed the bulk of the graffiti this morning, and traffic volumes and times were restored fairly quickly after we left the scene,” he said. “It was at an inconvenient time, and an inconvenient location, but for safety reasons primarily we elected to address it as soon as we could. … We certainly appreciate any patience and apologize for any inconvenience this might have created.”

Tridgell said IDOT was investigating who sprayed the graffiti on the sign.

“This is an extremely dangerous thing to be doing. If anyone sees any of this taking place at any time, they should call law enforcement immediately,” he said.