Whitestone Expressway Reconstruction
Tully was awarded this contract in February of 2003 to reconstruct the Whitestone Expressway. Originally started as a joint venture between Tully Construction and A. J. Pegno Construction, Tully completed the project as the sole contractor on the job. A. J. Pegno Construction was acquired by Tully over the course of the job. This project encompassed the extensive interchange between the Whitestone Expressway and the Van Wyck Expressway which was repaired and modified, as well as replacement of the northbound superstructure over Flushing Creek. The Whitestone expressway was improved from Linden Place to the Whitestone Bridge, as well as to the Cross Island Parkway interchange under this contract as well.
The bridge over Flushing Creek was replaced with 3 superstructures in order to create a safer environment and reduce the number of accidents in the area. Much of the new steel in the superstructures was comprised of massive 60 foot plus long tub girders which were constructed and erected with extreme precision. In order to construct the new bridge six piers were required to be constructed in the water. To build these piers Tully constructed cofferdams for each.
For this job six cofferdams were constructed to build piers for the Flushing Creek Bridge. The cofferdams were approximately 30 feet by 40 feet, sheets were driven and were braced with 3-5 whalers depending on the elevation to complete the dams. The cofferdams were excavated using buckets to a depth 20 feet below the mud line. Cranes used stacks of crane mats in order to be located close to the cofferdams and allow the work to be preformed. Excavation between the sheets was preformed using a pump to vacuum the material out of the cofferdams. The cofferdams were sealed by divers and the sealing process was completed using tremies. The tremies were poured in two layers, an initial four foot pour, followed by a six pour to complete the 10 foot tremie. The cofferdams maintained a head differential between 20 to 30 feet from mean high water depending on the water level that was being maintained in the cofferdams. The lower differential was due to phases where the lower levels of the cofferdam were to be filled with water, and the resulting forces served to keep the dam structurally sound without the use of whalers.
All in total, Tully Construction safely excavated approximately 5,500 cubic yards (4200 cubic meters) of material for the six cofferdams. The tremies totaling approximately 2,700 cuyds (2,000 cubic meters) of concrete were successfully poured to seal the bottom of each cofferdam. Tully executed the work performed swiftly and safely, constructing the cofferdam system, and the piers in accordance with the contract.