If you're driving in the Aurora, Ill. area this week, be prepared to share the road with a 90-foot chunk of concrete weighing 92 tons.

The Illinois State Toll Highway Authority Wednesday started moving 40 arch segments that will span the new westbound bridge on I-88 over the Fox River.

The arch segments won't be traveling alone, however, on their 5-mile journey. They'll be lying on 90-foot, heavy-load, semitrailer trucks and accompanied by state and local police.

There are 40 arch beam supports in all to be transferred from a construction yard in North Aurora to the site of the new bridge. Tollway officials said about six deliveries a day will occur at 1.5-hour intervals between 6 a.m. and 5 p.m. The move will take two weeks, depending on weather.

The arches will be transported on sections of Butterfield Road and Route 25 and will not affect traffic on I-88.

"The only impact is to local roads," agency spokeswoman Jan Kemp said.

She asked drivers who encounter the procession to be patient. "The vehicles are moving at a slow pace, so if you're behind, you'll be moving slow."

The structure is the only arched bridge in the tollway system. It was designed to reflect the style of the original Fox River bridge.

The bridge construction is part of widening and reconstruction of I-88 from two lanes to three lanes in each direction. An eastbound bridge was finished in 2008 and the westbound version should be completed by the end of the year.