Conti Enterprises, Inc.

Client:

Triborough Bridge and Tunnel Authority

Scope Of Work

The bridge now serves over 200,000 commuters each day as a major connection between Queens and the Bronx via Interstate 678 over the East River in New York City.

Opened as a four-lane suspension bridge in 1939, the 72-year-old structure, which had been increased to six lanes over the years, needed further capacity improvements as well as modernization.

Conti reconstructed the Bronx approach for this major historic continuous span steel bridge, which included widening the bridge deck, adding two lanes to the approach, demolishing and replacing the old piers and upgrading the lower garage service building. Utilizing careful orchestration and skilled project management, Conti’s first step was to construct new piers and install multi-rotational bearings which were critical schedule items for the new steel installation. This drove concrete pours and ultimately the phased traffic shifts. The team constructed extensive temporary shoring to support the existing piers so sections could be demolished in stages.

Implementing complex phasing to minimize impact on the heavy traffic flow, the team constructed new piers in advance of deck demolition under the existing structure, requiring low headroom equipment to install mini-piles for pier construction. These difficult drilling conditions for the mini-piles restricted the use of traditional equipment, so Conti deployed a highly innovative percussive down-hole hammer along with grouting through the hammer bit to successfully install the mini-piles.

The team used a movable barrier system so three lanes of traffic remained opened in the peak direction during rush hour, and all lane closures successfully met the 319-day restriction window.