Big Rock Bridge, 2005

Big Rock Creek Big Rock, IL

Satellite View of Bridge Location View Larger Map

USE:  Pedestrian

SPAN:  220'


TOWERS:  40' tall, A 588 Weathering Steel

ANCHORS:  6' x 6' Earth Anchor, Each Mainline

MAINLINES:  1-1/2" Galvanized Structural Strand

Big Rock Bridge, 2005

Big Rock Creek Bridge provides a key pedestrian link in the Big Rock Forest Preserve trail system. Located on 468 acres in south central Kane County, IL (just west of Chicago), this recently developed park is a triumph of conservation in the face of intense development pressures. Despite rapidly expanding exurban cityscapes nearby, visitors to Big Rock Forest Preserve are rewarded with a rare opportunity for viewing wildlife, nature study, and hiking. A tributary to the Fox River System, Big Rock Creek has been identified as a Class A stream, one of the finest and highest quality streams in eastern Illinois.

Ann W. Davis writes the following of her Big Rock Forest Preserve experience in Chicago Wilderness Magazine:

In early summer, as slivers of light sneak through the white oaks to the east, a noisy kingfisher - seeking a meal of fish - skims above the 32-acre quarry lake at Big Rock Forest Preserve.

Since its initial acquisition in 1991 of land in the southwest corner of Big Rock Township, the Forest Preserve District of Kane County (FPDKC) has purchased additional parcels. Today, with roughly 468 acres, Big Rock is among the district's largest properties.

When Big Rock Creek broke its banks during heavy rains in 1996, it burst through to the abandoned limestone quarry beside it, filling the 65-foot-deep pit and creating habitat for fish, including bluegill, black crappie, largemouth bass, and sunfish. After building an access road, parking lot, and pedestrian bridge, the district opened the site to the public.

We stroll northeast on an unpaved road that is sandwiched between Big Rock Creek and the quarry lake. Below us, a ledge of dolomite bedrock parallels the water's edge. Where the trail turns north, slabs of limestone - skeletal remains from the property's previous quarry life - are stacked cairn-like next to the path. Pointed stumps of silver maple and box elder, now weathered silver-gray, hint that beaver once foraged here.

"Big Rock is at the edge of two major divisions in Illinois that are defined by plant communities, glaciation, and topography," says Valerie DePrez, FPDKC nature programs supervisor. "Where the rock shelf is exposed, you can see scratches where the glacier left its mark 10,000 years ago. Fossils in the limestone include creatures from the Ordovician period, such as trilobites and brachiopods."

Farther on, we turn west. Hearing our footfalls, a pheasant hen bursts from her hiding place. Goldfinches bob overhead and add their sweet notes to the summer symphony. Visitors have seen other birds at Big Rock, including osprey, brown creeper, Acadian flycatcher, scarlet tanager, barred owl, tufted titmouse, and wild turkey. Hikers can reach the eastern portion of the preserve by leaving the lakeside road and heading east toward the oak grove along the ridge. Beyond that, the oxbows of Big Rock Creek snake through a verdant valley lined by high, sandy bluffs. Along the creek, massive sycamores tower over ironwood. Trees found in the 80-acre oak-hickory woodland include red, white, bur, and chinquapin oak; bitternut hickory; American and slippery elm; and purple mulberry.

"Other habitats at this diverse site include a high-quality fen and a perched pond [a pond that rests on a shelf, usually clay, above the water table]," notes Drew Ullberg, FPDKC director of planning and development.

Several years ago, the district seeded roughly 20 acres with prairie grasses and forbs. Other native plants at Big Rock include wingstem, swamp thistle, cup plant, spotted Joe Pye weed, sedges, cardinal flower, and Canada wild rye.

Completed in 2005, Sahale's bridge at Big Rock Creek Forest Preserve was subsequently awarded the American Council of Engineering Companies-Illinois Special Achievement in Engineering Excellence. Kane County Executive Director Monica Meyers writes in her letter to the Awards Committee:

"When the Forest Preserve District planned to span the creek with a trail bridge, the primary goal was to protect this precious natural resource. The District challenged the engineering team to implement a bridge design without piers or permanent structures in the creek or the adjacent wetlands. Furthermore, construction equipment or activities would not be allowed in these sensitive environmental areas during the construction process. This project fulfilled the District's mission of protecting and preserving our natural resources for the education, recreation, and pleasure of all its citizens. The engineering team surpassed the District's expectation by using innovative construction techniques to protect the stream during construction coupled with construction materials that will last a lifetime."

"This signature bridge has become a destination for forest preserve patrons and provides a unique platform for viewing and photographing birds and other wildlife."

Detailed View of Cable Stays.


Shuksan, bridge inspector.