I-90 BRIDGE TENDER 

TACOMA, WA

On behalf of the Washington State Department of Transportation, Art Anderson completed the design of a new bridge tender workboat used for inspections and maintenance on the I-90 floating bridge in Seattle, Washington.

The project began with a survey of the condition of a bridge tender workboat used to conduct inspections and maintenance of the Interstate 90 floating bridge in Seattle, Washington. The scope of the project included conducting a complete survey of the existing vessel’s condition and preparing a Preliminary Study Report to document with text and photographs the “as found” conditions. A follow-on Refurbishment/New Workboat Assessment Report was prepared to serve as the basis for the State’s decision to proceed with refurbishment or replacement of the vessel. The Preliminary Study Report provided a listing of all items surveyed, conditions found, and initial recommendations broken down into a standard Ship Work Breakdown System (SWBS) format.

For the subsequent Refurbishment/New Workboat Assessment Report, Art Anderson Associates personnel developed the options of refurbishing the vessel or purchasing a new workboat. This effort involved defining the refurbishment work items that were used to develop the cost estimates, identifying equipment upgrades with similar size and rated capacity to current
equipment, and defining improvements that meet all current applicable codes and standards, such as Tier 3 diesel engines. Work items spanned numerous ship systems, including mechanical, propulsion, controls, pilothouse systems, hull and coatings, crane, tank refurbishment, and fire suppression. The new construction option analysis incorporated all vessel mission requirements, and also analyzed alternative delivery methods (new design/build, COTS design/build, or build per existing design). Both of these analyses involved development of cost estimates for the work packages, schedules for bid/design/construction, and for the new option, an estimate of the value of the existing workboat.

The next project deliverable was a feasibility study and cost/benefit analysis comparing the two options. This included definition of new construction design requirements, and identification of required/desired improvements. After State acceptance of the reports, the new construction option was selected, and following the design phase, Art Anderson Associates will manage the construction of the new workboat. The Department of Transportation’s new bridge tender workboat is now under construction.