Daytime rivet removal operations were necessary on the Delaware River Turnpike Toll Bridge; however, Peregrine Falcons have been known to nest on two of the bridge piers. Since rivet removal work was necessary during nesting season, the New Jersey Turnpike Authority (NJTA) required the contractor to evaluate the potential for impact to nesting falcons.
Paul Carpenter Associates, Inc. (PCA) was retained to perform a noise measurement study to identify the increase in the ambient noise level at or within the vicinity of the Peregrine Falcon nesting areas below the bridge deck during typical rivet removing operations as well as the level of shielding provided by the bridge deck. Prior to nesting season, PCA deployed noise monitors proximate to the falcon nesting locations to document ambient noise levels. Tishman also staged typical rivet removal operations at one bridge panel point while PCA documented noise levels below the bridge deck, five feet above the deck and within a manlift with the rivet busting gun operator to document rivet busting source noise levels. Type I noise level meters were time synchronized for data comparison.
Subsequent to the noise measurement study, the level of shielding provided by the deck was identified. Further, PCA staff developed a project-specific model illustrating the two bridge piers on which the falcons were known to nest as well as all bridge panel points which were subject to rivet removal operations. The model allowed the user to select a bridge panel point and determine cumulative noise levels at each bridge pier from rivet busting operations as well as the level of increase over ambient. The model flagged exceedances from rivet busting operations at each pier, and the NJTA was able to determine precisely where the contractor could and could not work during nesting season in order to preclude impact.