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Rensselaer Technology Park

North Greenbush, New York

Stream and Wetland Crossing


Rensselaer Polytechnic Institute


Fraser, P.E., L.S., L.A., Ryan Biggs Associates


The Delaney Group



Technical Description:

  • Span: 36 ft, 83 ft-5 1/2 in
  • Rise: 8 ft, 22 ft-10 in
  • Length: 96 ft, 100 ft

Rensselaer Polytechnic Institute owns the Rensselaer Technology Park (Tech Park) which consists of 1,200 acres in New York’s Capital Region, 450 of which were master planned for technology-related enterprises. 250 of the acres were built out during Phases 1 and 2 while Phase 3’s focus was to accommodate the state-of-the-art $160 million General Electric (GE) Healthcare Digital X-Ray Detector Production Facility.

Because the GE facility had an aggressive construction schedule, a half-mile extension of road and utilities accessing the GE site needed to be permitted and built quickly. This extension crossed two regulated wetlands. Tech Park realized very early in the process that the Army Corps of Engineers’ permitting for traditional culvert-and-fill crossings would take too long. They agreed that “bottomless arch culverts” were the answer because they would avoid discharging fill into local waterways, and thus avoid the need for Corps permits.

The criteria for these bottomless culverts were exacting. The smaller culvert needed to cross a 15- foot wide wetland and have a low profile so that the road surface could pass over it while utilities passed under it. The larger culvert needed to cross a 60-foot wide wetland and stream and allow for six feet of fill over the crown to accommodate both the road and the utilities. Furthermore, the technology needed to be fabricated, delivered and erected in a short time span.

A 36’ x 8’ CON/SPAN® Bridge System, 96’ in length, was selected for the smaller crossing while an 83’- 5½” x 22’-10” BEBO® Concrete Arch System, 100’ feet in length, was selected for the larger crossing. The CON/SPAN is supported on standard reinforced concrete spread footings. The BEBO foundation is reinforced concrete pile caps supported by 52 piles on each side of the bridge. Sheet pilings were driven on the inboard sides of the pile cap excavations in order to preserve adjacent wetlands.

“The aggressive schedule within which the BEBO and CON/ SPAN structures were fabricated and erected, along with the avoidance of wetland disturbance they made possible, enabled us to complete our project ahead of the opening of the GE facility,” said Michael H. Wacholder, Director of the Rensselaer Technology Park. “We all are very pleased with the outcome.”

Tech Park purchased the CON/SPAN and BEBO systems directly from Contech and retained a highway heavy contractor for the installation. After completion of the footings, the erection of the CON/SPAN arches and MSE headwalls took only one day. After completion of the pile caps, the erection of the 25 pairs of BEBO arches took five days. Two cranes - one at 175T and one at 250 T - were employed during this process. As these cranes could not cross the large, regulated wetlands and stream, temporary access roads were constructed on both sides of each crossing. Contech technicians assisted the contractor’s personnel during each installation. At the time, this Tech Park BEBO bridge was the longest span in the United States.

The road, utilities and bridges were dedicated to the Town of North Greenbush as part of its public infrastructure. Because landscaping occupies ground surface over the two bridges beyond the edges of road pavement, they are seamlessly married to their surroundings. In fact, only the decorative fencing mounted atop headwalls gives any suggestion that structures lie beneath.

“The BEBO and CON/SPAN systems made it possible for us to integrate these two structures seamlessly into the fabric of the landscape,” said Roger Murman, RLA, Senior Landscape Architecht with Fraser, P.E., L.S., L.A, a Weston Company. “Mike [Wacholder] takes pride in the quality of the outdoor environment at the Park and these bridges fit perfectly with that aesthetic.”

The precast products were selected because of their ability to meet the exacting operational and scheduling requirements of the project.

Technical Description:

  • Span: 36 ft, 83 ft-5 1/2 in
  • Rise: 8 ft, 22 ft-10 in
  • Length: 96 ft, 100 ft

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