Bridge replacement for McDowell Grove being considered

Nine years after balking at the cost of replacing a bridge at McDowell Grove, DuPage County Forest Preserve commissioners are revisiting the idea.

District engineers in 2007 recommended installing a bridge to replace the 1940s-era, one-lane version crossing the West Branch of the DuPage River at the entrance to the preserve near Naperville.

Commissioners at the time were concerned about the estimated $1.7 million price tag, so they picked a cheaper option of repairing the structure and constructing a separate trail bridge for pedestrians.

But the bridge repairs never happened because of other projects, including recent work along the river.

Then in late 2014, an inspection found deterioration of the bridge's deck beams significant enough to reduce the structure's load rating to 5 tons, officials said. The life span of the bridge substructure is estimated to be about 20 years.

"If you just re-deck it, it will buy you some time," said Brock Lovelace, a project engineer with the district. "But eventually the piers and the abutments are going to be at the end of their life, and we're going to have to fix them. Any money you throw into it now is a temporary fix."

So staff members earlier this month recommended replacing the bridge as the only way to solve all the issues with the existing structure.

One safety concern with the bridge is that the road leading from Raymond Drive has a steep grade and an S-curve.

The recommended plan is to demolish the existing bridge and construct a two-lane structure that also will have a pedestrian trail. As part of that work, the entrance road that leads to the bridge will be realigned.

"We're going to straighten that out," Lovelace said. "And we're going to raise it up on the west a little bit just so it's not such a steep grade."

Commissioners have directed staffers to pursue engineering for the replacement.

On Tuesday, the board is expected to hire Wills Burke Kelsey Associates Ltd. to do engineering work for the bridge replacement. If approved, the firm will be paid $214,066 for the work, which will include developing different options for a new bridge.

It's not yet known how much more a new bridge would cost compared to the 2007 proposal. But officials say the district has additional money to use because other projects since that time were finished under budget.

If commissioners agree to build the new bridge, the plan is to start construction in spring 2017.