Bridge Replacement & Trail Improvements

Planning Project

McDowell Grove: Bridge Replacement & Trail Improvements

The main entrance and parking lot of McDowell Grove Forest Preserve in Naperville and a section of the West Branch DuPage River Trail will remain closed through the end of May 2018 to replace the preserve’s 70-year-old single-lane entrance bridge. 


The new two-lane bridge will accommodate cars and trucks and have a separate elevated trail with a barrier wall for pedestrian and bicycle traffic. A clear span of the river and higher elevation will minimize debris buildup during floods. The $1.96 million project will also reconfigure the entrance to eliminate a dangerous curve and reroute the West Branch DuPage River trail to avoid the parking lot. 

During construction visitors will be able to reach McDowell Grove via turf and limestone trails from the east, south and north and fish along Mud Lake and the West Branch DuPage River outside of the work site, but hikers and bikers who want to cross the preserve via the West Branch DuPage River Trail will need to take a 6.8-mile C-shaped detour (PDF) through Naperville.

From the north end of McDowell Grove, the detour will go west along Ferry Road, southwest on the Illinois Prairie Path-Aurora Branch, and then along Fairway Drive, Campbell Drive and Bruce Lane to Brookdale Road, where it will cross Raymond Drive and reconnect with the West Branch DuPage River Trail near Fawell Dam.

The existing entrance into McDowell Grove Forest Preserve is located on the east side of Raymond Drive, approximately 0.35-miles south of Diehl Road, in unincorporated Naperville. The two-lane entrance road connects to a one-lane vehicular bridge over the West Branch DuPage River, which leads to an existing parking on the east side of the river. The bridge was originally constructed in the 1940s, with superstructure improvements made over the years.

There are several issues with the existing bridge and entrance road:

1. The two-lane entrance road approaches the one-lane bridge on a sharp curve on a steep down gradient creating safety concerns during wet or icy conditions. 

2. The bridge serves as both the primary pedestrian and vehicular access across the river and is considered part of the heavily utilized West Branch Regional Trail. Due to the limited width of the bridge, pedestrian safety is a concern due to the potential for vehicular/pedestrian conflicts.

3. The bridge is constructed on driven piles within the river which typically catch debris during flood events. Coupled with the fact that the bridge deck elevation is lower than the base flood elevation, the ability for the aging bridge to withstand the structural stresses imposed by flood conditions in the future has become a concern.

4. The bridge is restricted to a 5-ton weight limit.



Construction plans and specifications were released for public bid on March 29, 2017, and the District executed a $1,964,776.68 construction contract with Dunnet Bay Construction Company on May 16, 2017. The District also executed a $115,906.27 Professional Service contract with WBK Engineering to perform construction engineering services. Construction began in August 2017 and is expected to be complete by Memorial Day 2018.

The work zone — including the entrance road, parking lot and a portion of the West Branch DuPage River Trail (shown on preserve closure map (PDF) in red) — will be off-limits to the public through the end of May 2018. Forest preserve visitors may use the 6.8-mile detour through Naperville along the 23-mile regional trail.



The Board of Commissioners has authorized approximately $2,198,000 in bond funds and yearly appropriated construction development funds to construct this project.



In 2006, the District’s Board of Commissioners approved a preliminary engineering contract with Strand Associates to determine potential alternatives for replacement of the bridge. Due to financial constraints, the Board chose to move forward with design engineering for only replacing the deck of the existing bridge, and constructing a new pedestrian bridge to the north along with associated trail improvements. The project was placed on hold shortly thereafter due to anticipated river restoration and dam removal work within the preserve. The river work was officially completed in 2014.

In 2014, an inspection of the bridge found conditions that warranted downgrading the weight limit of the bridge to 5 tons. This weight restriction has significantly impacted access to the preserve for emergency vehicles and District operations. In 2015, the District Board of Commissioners directed executed a contract with WBK Engineering to design a new bridge that will carry two lanes of traffic and a multi-use trail. The bridge was designed to provide a clear span over the river, and correct the alignment of the road as it approaches the bridge from Raymond Drive.