• Project Type

    Hydrographic Services

  • Date

    April 2023

  • Location

    South – Regions 10 & 11

  • Role

    Cross Section Fathometer Survey
    Dive Team Support

Fee: $549K

New York State Department of Transportation (NYSDOT) divides its Bridge Diving and Fathometer Survey Services agreements into three sections: East, West, and South. As part of this effort, Prudent Engineering is conducting bridge fathometer surveys in Regions 10 and 11 for the 2021 – 2024 inspection cycle.

The scope of work on this project required fathometer surveys and below-water condition inspection by a dive team of structures identified by NYSDOT. Both diving and fathometer teams use photography, sketches, and reports to support their inspection of the selected structure.

The fathometer survey and mapping area includes the underwater portion of the bridge structures and the surrounding area at a limit of 100 feet upstream and downstream of the bridge. To date Prudent has completed 12 scheduled bridge fathometer surveys in Suffolk and Nassau Counties (Region 10) and 17 scheduled bridge fathometer surveys in the counties of Region 11. Additionally, Prudent has conducted two emergency bridge inspections and two post-storm bridge inspections.

Surveys are conducted using R2Sonic 20204 multi-beam sonar, Trimble-461 GPS heading bundle and an IMU-108 motion sensor. These surveys are supplemented with adjacent land surveys using Trimble S-5 robotic total station and an R-8 RTK GPS.

Prudent’s fathometer team consists of a Hydrographic Party Chief, plus two Hydrographic Instrument Persons.

Surveys have involved Prudent’s entire array of their vessels and equipment from the remote control multi-beam Z- boat with an R2 Sonic 2020 multi-beam sonar and a Pos-MV Wavemaster motion sensor to their 31-foot Elco catamaran equipped with R2 sonic 2024 multi-beam sonar.