Part of the City of Bellevue’s Downtown Access Project, the improvements for the NE 8th Street/116th Avenue NE Intersection included a new traffic signal system, illumination, curb and gutter, sidewalk, storm drainage improvements (including detention and water quality treatment), roadway widening and resurfacing, landscaping, modifying the existing street lighting system to accommodate the widening, gateway enhancements, and public art. The project involved considerable coordination with the City of Bellevue, WSDOT and affected utilities.

Tetra Tech INCA provided design services for improvements to the north, east, and south legs of the NE 8th Street and 116th Avenue NE intersection, including replacement of an existing traffic signal. The project included widening the east leg of the intersection to accommodate eastbound-to-northbound and westbound-to-southbound dual left-turn lanes on NE 8th Street; extending the existing right-turn pocket on 116th Avenue NE approximately 100 feet for a total length of 300 feet; widening the north leg of the intersection to provide an additional right-turn lane approximately 300 feet in length; and widening the south leg of the intersection to accommodate the new dual left-turn lanes.

The NE 85th Street rechannelization provides on-street parking on a central downtown street with adjacent businesses, improve traffic flow through intersections, provide loading areas in front of the mixed use residential that will not block bike and traffic lanes, and improve aesthetics along the corridor. Improvements near the fire station, library and post office are of particular concern due to the highly used or important driveways. The study considered the area from 154th Avenue NE to 166th Avenue NE.

INCA prepared the plans, specifications, and estimate for the construction of a flashing crosswalk system on NE 124th Street near the intersection of 105th Avenue NE.  This system includes in-pavement flashing lights, illumination, power service, signage, and sidewalk revisions to meet ADA requirements.

The project was part of an on-call agreement with King County. INCA Engineers provided King County Department of Transportation with professional engineering services on a work order basis for various transportation projects, which included ITS strategic planning, preliminary and final design, communications analysis and design traffic analysis, traffic forecasting and modeling, and signal and illumination design.

Tetra Tech INCA prepared engineering studies and plans, specifications and estimates to stabilize the portion of the right dam abutment that supports the pedestrian access bridge to the air vent shaft at Mud Mountain Dam.

In conjunction with the slope stabilization and grading work, INCA designed new domestic water, fire supply, and intake tower flushing water systems to replace existing services demolished during new construction. This work included the preparation of plans and specifications for three new 50,000-gallon water tanks, three new pipelines, thrust restraint systems, air release/vacuum valves, and appurtenances.

INCA surveyors provided mapping for stability correction design showing existing slope conditions and planimetric features. All work was tied to the Mud Mountain Dam horizontal and vertical control network.

Tetra Tech INCA prepared design memorandums and final plans and specifications for the upstream guard wall and upstream guide wall at the Marmet Lock, on the Kanahwa River. The first phase of the work consisted of preparing a screening level study of two alternatives in sufficient detail to determine a relative cost estimate for each alternative.

The precast concrete beams were designed for an optional segmental construction to facilitate a smaller fabricator, handling, and transport. Pier cap beams were designed as precast shells to improve constructability and reduce on-site construction time. Finite element analysis was used for the design of the structure and foundation, including 3-D modeling using SAP 2000 for the girders and cap beam supports.