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Bridge demolition - Work on bridge piers without diverting traffic.

The Job:

Adding two additional lanes to a four-lane bridge over the Pompton River in New Jersey to accommodate traffic growth. The existing bridge piers were capable of supporting the two additional lanes as they stood, but the upper part of the piers had to be widened. This meant partially removing the upper section so that new concrete could be cast.

The Requirements:

The lower part of the pile was under no circumstances to sustain any damage. Needless to say, the construction work had to be carried out as economically as possible and without disrupting the traffic to any marked extent.

The Solution:

A Darda hydraulic rock and concrete splitter consisting of two to three C 11 SN splitting cylinders and a hydraulic power unit. Following the partial removal of the carriageway, the workers drilled a row of horizontal holes, 45 mm in diameter and at intervals of 0.6 m, in the upper part of the pier, penetrating right through the 1.2 m thick concrete. Splitting cylinders were then placed in every second hole, generating a combined splitting force of around 1000 tons. The concrete was split along the line of drill-holes in less than a minute. This process was repeated until the pier was split over a distance of 11 m. Two workers were able to split a pier in less than 15 minutes (excluding drilling operations), after which the 11 m long dislodged sections were broken down into smaller pieces by a number of vertical splits. Finally, the upper part of the pier was extended with ribbed steel reinforced concrete, making it capable of supporting a six-lane highway.