While motorists have waited for the Interstate 80 bridge to be repaired, questions remain about why it is taking so long and why more accommodations can't be made for two-way traffic.

George Ryan, a deputy director for the Illinois Department of Transportation, has provided more details and explanations about the bridge repair, which is to start April 5 when the bridge traffic will be restricted to one westbound lane. By mid-July, one side should reopen to two-way traffic with the full bridge re-opening by Nov. 1, 2010.

The $10.5 million repair will include replacing cracked stringers and floor beams. DOT officials hope to get another 10 to 15 years out of the bridge before having to do more work.

Q. Why is it taking so long for repairs to start on the bridge?

A. Ryan said inspectors first had to explore more than 1,000 areas on the bridge for cracks and other problems. They also conducted tests, including sending trucks across the bridge with different weight loads to see how the structure

handled the stress. As a result, they came up with a plan for replacing portions of the bridge's superstructure. They will also make more than 1,600 welds to help stabilize the bridge.

"We really climbed all over the bridge," Ryan said. "That took quite a bit of time to do."

Ryan said it's better for the strength of the welds if that work is not done during winter months. Working on the bridge during winter conditions can also make it less safe for motorists, he said.

The delay also gives steel mills time to manufacture the fittings the contractors will need to repair the bridge, he added.

Q. Why are so many welds needed?

A. During recent tests, inspectors found the bridge deck moves more than they expected or would like. They don't know if it's what led to the recent problems with the bridge but have decided to weld several locations to reduce the movement, Ryan said.

The welds will fill a space narrower than a sheet of paper that inspectors found between the floor beams and bridge deck, Ryan said. When the bridge was first constructed, the builders didn't foresee such a problem, he added.

"They didn't suspect they would get that type of movement," he said.

Q. What is the DOT doing to speed up the repair process?

A. The contract for the repairs will be bid in November. When work starts April 5, the contractor will be on a tight deadline and could earn up to $1 million in incentives if crews complete the first of two stages by July 1. If they go past July 15, they could be fined up to $20,000 a day. There are more incentives to get the full project finished by Nov. 1.

"They're going to have to work double shifts and long weekends to get done by July 15," Ryan said, adding DOT inspectors will be on site to make sure the work is done properly.

Q. How will the contractor get under the bridge to make the repairs?

A. The DOT plan allows the contractor to cut holes through the deck to get down to 74 floor beams that will be partially replaced. The holes will extend across both lanes on the side of the bridge that is closed. The westbound side will be finished in the first stage, and the eastbound side during the second.

Q. Are there any other bridges with a similar design built in the 1960s that are facing the same problems?

A. The two-girder design on the I-80 bridge was unusual for Illinois, Ryan said, and was used to save money on the cost of construction.

Ryan said there is only one other bridge in the region with a similar design, and it is much smaller. He did not remember the location of that bridge, but he said it was checked after the cracks in the I-80 bridge were found and no problems were discovered.

"I'm not sure, but (the I-80 bridge) might be the only one in Illinois of that size" and design, he said.

Q. Are people staying off the bridge because of the "critical" evaluation it received in May?

A. Ryan said the DOT has not done a recent traffic count, but he's sure the traffic volume is down slightly.

"I would anticipate it is down a little bit, but being down to one lane (both directions), it is still functional," he said, adding many cross-country motorists are probably taking alternate routes when they see the construction signs.

Q. Is it possible for the DOT to restrict truck traffic to the bridge so one outside lane can re-open and there can be two-way local traffic on one side of the bridge?

A. Ryan said it would be difficult to restrict trucks because even if detour signs are put up, some will still take the I-80 bridge instead of Interstate 280. He also said any amount of weight on the outside lanes could cause further damage.

The DOT looked at various options for traffic restrictions, including shutting down the entire bridge during construction, Ryan said, but found a full closure would not have significantly reduced the amount of time it will take to repair the bridge.

Q. If traffic has to be restricted to one lane on the eastbound side of the bridge, can the DOT set up traffic lights to alternate traffic in both directions?

A. Ryan said the DOT will not use traffic signals on the interstate because it would be dangerous and would tie up traffic. He said such a system would not be able to handle the number of cars coming through.

"When you're on the interstate, people don't really consider that they're going to have to stop for a light," he said. "You might sit through multiple lights (as traffic backs up) and could possibly get rear ended."

Q. Why don't the lights on the bridge work?

A. When the bridge deck was replaced in the 1990s, the bridge lights were moved. In their new locations, the lights experienced more vibrations and the bulbs the DOT installed kept breaking, Ryan said. The DOT recently installed new fittings for the light poles that reduce vibrations, so lights will be on during the repair project.