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Triad’s 3D Laser Scanner Plays Role in Beach Erosion Study

SEE TRIAD SURVEYORS IN ACTION: click here to watch Kitsap Transit's YouTube video, "FAST FERRY RESEARCH PROJECT."
Every day Triad employees are challenged to accommodate the economic demands of a growing Seattle-area while protecting the environment and our quality of life. This reality was particularly evident when Triad worked on a project to bring back fast, passenger-only ferries to the Bremerton/Seattle crossing.  
 
Over 30 years ago, high-speed, passenger-only ferries were used to cut in half the hour-long crossing time between Bremerton and Seattle, but ferry wakes took a toll on the shoreline and sea life in the confined waterways of Rich Passage. When the ferries slowed down to protect the beaches, crossing times increased, the ferry system lost passengers and funding, and the passenger-only run was abandoned.
 
However, the demand for a 30-minute ferry commute to and from Seattle didn’t go away, and in 2003, the state began looking for ways to move people faster between the two communities and protect sensitive beaches along the route. An extensive research project, started by the Washington State Ferry System and later turned over to Kitsap Transit, brought together shoreline residents, scientists, boat designers, engineers, biologists, and surveyors.
The team's goal was to design a boat hull that would create a wave that would dissipate before reaching shore. The project included five phases:
  1. Physical and biological data collection
  2. Numerical modeling study
  3. Vessel selection and design
  4. Testing
  5. Communication
For the beach-erosion study in Phase 1, Triad surveyors, working with Golder Associates and Senior Coastal Engineer, Jessica Coté, began the process of precisely mapping site conditions. To do so we conducted 3D laser scans of three beach segments along both shores of Rich Passage. The project included a few unusual logistical challenges:
  1. Limited scanning window: Our work had to be done during a two-hour window -- one hour before to one hour after low tide. That often meant surveying in the middle of the night.
  2. Unusual job site: The three targeted shorelines could only be accessed by boat, adding an element of coordination and complexity.
  3. Porting equipment: Usually we unload equipment from our survey van directly to the job site. This project required additional porting by boat and to and from rocky shorelines. 
In-house, post-processing by our Survey Technician involved stitching the scans together using pre-determined survey targets as points of reference. The result was a single “point cloud” of data that we delivered to Golder engineers who used it to conduct their extensive beach erosion differential analysis.  
In 2013, the custom-designed catamaran Rich Passage 1 was launched, combining a low wake, fuel efficiency, and speed. With the two-year research phase now complete, Kitsap Transit continues to study the financial viability of sustainable and fast passenger-only ferry service.
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Copyright © 2015 Triad, a division of David Evans and Associates, All rights reserved.


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