Project Overview
PND led a comprehensive site investigation and design of a new floating layup dock facility for the Ketchikan Airport Ferry on Gravina Island, a project developed for the Alaska Department of Transportation & Public Facilities (DOT&PF). PND provided a geotechnical assessment, coastal engineering, site/utility design, waterfront structural design, and construction administration and inspection services. The structural design included the large floating dock, vehicle transfer bridge, abutment, and float mooring dolphins. The completed dock, designed to replace the existing deteriorated facility, is a 250-foot by 85-foot concrete floating pontoon. The new float mooring dolphins included both rock sockets and tension anchors to safely transfer the large forces from the float into the seafloor.
PND performed the vessel mooring and berthing analyses and developed the mooring/breasting dolphin and fender systems designed to accommodate the Ketchikan Gateway Borough’s ferry operations. The civil design included a two-lane approach road, grading plans, utility design, and shoreline erosion protection. The utility systems incorporated electrical power, lighting, communications, potable water, and fire suppression services to both the float and moored vessels.
PND completed final design and provided bid support for the project in June 2020. Construction began in January 2021, with PND providing construction administration and inspection services throughout project execution. The facility was designed to support the borough’s pair of double-ended ferry vessels while accommodating additional ferries planned for future operations.
Our Role
- Civil Engineering: developed a widened and paved vehicle approach to the facility; site design included grading/drainage, water/fire/utilities, and tie-ins to the existing utilities
- Coastal Engineering: evaluated wind driven waves and wake wave forces on floating dock and mooring dolphin piles
- Contract Administration and Construction Support: provided bid support, submittal/RFI review, fabrication inspection, construction inspection, and project commissioning during construction
- Geotechnical Engineering: investigated existing site conditions and developed a geotechnical design report for the final design of the facility
- Structural Engineering: performed the detailed structural analysis and design on the concrete float dock structure, vehicle transfer bridge, and mooring dolphins; the vehicle transfer bridge and floating dock were designed to support AASHTO H-20 service vehicles
- Waterfront Engineering: designed floating dock, vehicle transfer bridge, and float mooring dolphins; developed bridge load rating report to DOT&PF standards
New Ferry Facility Improves Critical Alaska Transportation Links
PND’s design for the Ketchikan Airport Ferry facility focused on a safe, reliable, and enduring replacement for the deteriorated layup facility with a modern, low-maintenance floating berth that enhanced ferry operations serving Gravina Island. The new facility was essential for the Ketchikan Gateway Borough airport ferry service, which provides critical transportation links for residents and travelers accessing the airport. The upgraded floating dock facility accommodates two shuttle ferries simultaneously while providing transient moorage opportunities for other vessels, significantly improving operational flexibility and capacity. The large float provides service vehicle access to support maintenance and fueling operations for the vessels. The robust concrete floating dock was designed with comprehensive utility systems to ensure reliable year-round operations in Alaska’s challenging marine environment. The protecting concrete structure was detailed for a 75-year design life with limited maintenance required.
The successful completion of this project delivered enhanced transportation infrastructure that strengthened connectivity between the City of Ketchikan and its airport on an adjacent island. This project is a part of a larger program to improve the connectivity between the islands and supports both local community needs and regional economic development.
Tons
weight of the 250-foot x 85-foot floating dock
Feet
vertical distance between highest and lowest tides
Square Feet
area of additional, usable waterfront space provided by the project
