Old Plank Trail Road Bridge
Frankfort, Ill.
Teng & Associates

A modern gateway to an old-fashioned town

© Russell Phillips

For more photos click on 'photos & drawings' above. To see the people and products behind this project click on 'people & products.'

In replacing the existing railroad overpass over U.S. Route 45, the architects faced a challenge. The village envisioned a "landmark design" for their new pedestrian/bike path bridge, one that would raise the existing roadway by 14 feet to alleviate annual springtime flooding and arrive at or below construction and maintenance costs of a typical bridge. Compounding this task, residents wanted new development to reinforce the village's 1890s charm.

Meeting and surpassing these challenges, the new cable bridge boasts several problem-solving advantages over a more traditional design. Since the existing rail path crossed the roadway at an oblique angle, the bridge required a longer, and therefore deeper, spanning member. The cable stay design re-oriented the structural frame perpendicular to the roadway, thereby reducing the span distance for dead loads. Braces for lateral support on abutments at either side of the roadway strengthened the bridge deck. Decreasing the required depth of the spanning members allowed a similar reduction in the height of the embankment, and the resulting shorter grade transition yielded cost savings in land acquisition.

In this bridge, the dynamic structure is the architecture. Visible from every direction, it stands as a gateway to the village of Frankfort. Indeed, inserting this modern solution into the quaint turn-of-the-century architecture and streetscape provoked more than a few concerns among residents. This design challenged the notion of building new to look old, and ultimately succeeded in its forward-looking stance. In the words of Village President Raymond Rossi, the new bridge "did more than exceed expectations; it changed those expectations for generations to come."

Formal name of Project:
Old Plank Trail Road Bridge over U.S. Route 45

Location:
Frankfort, Ill.

Measurements:
180 foot clear span, 10 foot walkway deck width

Owner:
Illinois Department of Transportation

Architect:
Teng & Associates, Inc.
205 N. Michigan Avenue
Chicago, Illinois 60601
312. 616. 0000
www.teng.com

R. Shankar Nair, Ph.D., S.E., P.E. & Thomas Hoepf, AIA