Making a Connection
Within the Middlefork Savanna Forest Preserve in Lake County, a set of railroad tracks servicing Metra and some freight train lines, prevented residential communities, Lake Forest Academy, and Townline Community Park, from safe access to miles of multi-use trails within this dedicated Illinois nature preserve.
A Divide that Needed Bridged
The Middlefork Savanna Trail Connection creates a safer environment for pedestrians and bicyclists by providing a new 8-foot wide shared-use path connecting user groups with the Forest Preserve trail network. The centerpiece of the project was the new bridge, which provides the only pedestrian/bicycle railroad track crossing within Lake Forest. The trail connection is also part of an effort to link larger regional trail networks such as the North Shore Trail, the Des Plaines River Trail, the Skokie Valley Trail, and the Robert McClory Trail.
Civiltech provided Phase I, Phase II, Phase III, and Structural Engineering services as the prime consultant on this exciting project. Each phase had unique challenges and required extensive stakeholder coordination.
This Project Incorporates the Following:
- Reuse of historic structures
- Multi-use path realignment
- ADA compliance
- Complex construction parameters
- Metra and railroad coordination
- Landscape preservation
- Multiple IDOT department coordination
Scope of Services
- Project Development Report
- Preparation of Contract Plans, Specifications, and Estimates
- Multiuse Bridge
- Bikeway and Pedestrian Facility Design
- Traffic Signal Design
- Interagency Coordination
- Resident Engineering
- Construction Documentation
- Coordination and Public Involvement
- QC/QA Material Testing
Preserving History, Preserving Nature
Lake Forest Academy is located on the historic site of the former J. Ogden Armour Estate. The former estate’s drive had come from the east, crossing the railroad tracks, and terminating at the site on the west side of the tracks. The Armour Estate’s original bridge structure was demolished in 1954, however decorative, concrete, abutments remained on either side of the tracks. Civiltech chose to locate the new bridge in the same location as the historic abutments, which acted as the starting point for all of the alignment alternatives.
One challenge of developing alignments for the new path involved maintaining certain trees while still meeting ADA accessibility requirements. A swath of trees had to be removed to accommodate the path on the west side of the tracks. Some of the trees were significant due to age or size and Civiltech modified alternatives to avoid damaging or removing them. Another important challenge was determining safe and convenient locations to install new crosswalks with pedestrian and bicycle actuations at roads and intersections located on the west side of the tracks. The new cross walks were designed to accommodate access to the bridge and the forest preserve trails on the east side of the tracks from residential areas, Lake Forest Academy, and Townline Community Park located on the west side.
Extensive Phase I stakeholder coordination included several IDOT Bureaus including Hydraulics, Traffic, and Geometrics. Since the trail connection included a bridge over the railroad tracks, both Phase I and Phase II engineering services involved close coordination with Metra.
Blending the New with the Historic
Civiltech’s structural engineers designed a new 221-foot long bridge structure to cross the railroad tracks as the final link of the trail connection. The new 12-foot wide, steel frame and timber planked bridge was placed in the same location as the original bridge servicing the J. Ogden Armour Estate and was designed to sit within the existing concrete abutments. The structural engineers had chosen to utilize the concrete abutments from the old bridge to preserve the historic aesthetic and reference the former bridge and estate. The existing abutments are now merely decorative with the structural footings for the new bridge hidden behind them. A challenge of the new bridge design was the critical verification of the dimensions and structural support within the existing abutments. Also, the bridge had to be designed in five separate sections for transport to the site, with the ability to assemble the single structure in the field.
Anticipation, Coffee, and a 2 a.m. Hoist
The construction of the trail and new bridge was phased such that the trails on either side of the railroad tracks were complete. Then, in the early hours of the morning on Saturday, September 9th, 2018, before an audience of about 40 on-lookers, and with adrenaline, anticipation, coffee, and donuts holding tiredness at bay, Civiltech’s Resident Engineer coordinated the placement of the new bridge structure, the centerpiece and final link of the new Middlefork Savanna Trail Connection. The hearty crowd that had gathered at 2 a.m. to watch the bridge erection included staff from Civiltech, Lake County, and the Lake County Forest Preserve District, as well as curious neighbors.
The planning, preparation, verification, and coordination necessary to complete the bridge installation was complex and multi-faceted creating tremendous anticipation and anxiousness in the build-up to lifting and placing the bridge. The most critical factor was coordination with Metra’s schedule which dictated the 3 hour window, between 2 am and 5 am, in which the entire bridge installation needed to occur. Adding further complexity and coordination to that tight time frame, freight trains were still allowed to pass through with restrictions on how long they could be held-up.
Exceeding Owners Needs
The Lake County Forest Preserve District faced the challenge of providing safe access to the Middlefork Savanna Forest Preserve and the Melody Farm Nature Preserve from residential areas, Lake Forest Academy, and Townline Community Park, as well as connecting regional trails, due to railroad tracks and IL Route 60 providing an obstacle to pedestrians and bicycles.
Civiltech’s bridge and trail connection design provided the community safe access to the Middlefork Savanna Forest Preserve and trail system. The improvement provided the community with a state-of-the-art bridge and the only pedestrian/bicycle railroad track crossing in Lake Forest, while honoring the history of the region.