INCA Engineers provided design, construction management services, and on-site inspection for the restoration of a portion of Marine View Drive roadway that had slid approximately 10 feet due to an, approximately 400-foot wide, adjacent landslide. This project included the design of a 150-foot long space pile wall consisting of 5-foot diameter by 25-foot deep lean concrete lagging shafts and 4-foot diameter, 75-foot deep structural concrete shafts. The effort included evaluation of alternative retaining wall systems and coordination of geotechnical efforts.

The Marine View Drive Bridge (SR 509) was first identified in 1989 as a box-culvert replacement in the Des Moines Creek Restoration Project. The 4-foot by 6-foot concrete box-culvert was built under embankment fill approximately 60-feet high, which separated Des Moines Beach Park from Des Moines Creek Park. Urban development resulted in an increased volume of water discharge to the existing culvert and as a result, the culvert acted as a high velocity fish barrier.

INCA Engineers provided plans, specifications, and estimates for construction of a bridge to replace the existing culvert. The design resolved several issues and included a pedestrian trail to connect parks, fish passage to the upper reaches of the creek, increased hydraulic capacity, and a utility corridor for the Midway Sewer District’s proposed 48-inch diameter sewer outfall. The project incorporated a concrete bridge, retaining walls, pedestrian trail, stream relocation, landscaping, storm drainage, paving, curbs and gutters, and other improvements. The street drainage design included modifications to the existing drainage system in the immediate vicinity of the bridge improvement.

This project has won the ACEC Engineering Excellence Award ”Bronze for Original or Innovative Application of New or Existing Techniques” 2008 and the ASCE “Award of Excellence” 2007.

INCA led a multi-disciplined architectural and engineering team in the site selection, environmental analysis, and design of the new Lynnwood Transit Center for Sound Transit. The new expanded facility includes 20 bus bays, passenger loading zones with shelters, a customer service center, and 300 additional parking stalls.

The project was developed in phases: for the first phase of this project, INCA was responsible for site selection and planning, preliminary engineering, and NEPA/SEPA environmental documentation for the proposed transit center, park-and-ride enhancements, and HOV direct access to I-5, which included a freeway flyer alternative. For the second phase, INCA was responsible for design mapping and preparing plans, specifications, and estimates (PS&E) for the transit center and park-and-ride improvements.

INCA provided design support and shop drawing review for Sound Transit during construction.

Tetra Tech INCA provided detail design and prepared manufacturing drawings for a new gate car to be used to open and close ten vertical lift spillway gates at the Lower Baker Dam in Skagit County, Washington. The gate car traverses the existing spillway on curved rails to access each of the gates, and can automatically engage and disengage each of the gates, for their operation, through either the controls mounted inside the cab or two pendant controls mounted outside the car cab.

The gate car is a hydraulically-operated, self-propelled, self-contained, gate operating system consisting of an enclosed and heated carriage-mounted support structure with an overhead 50 kip capacity hydraulic cylinder hoisting system with 22 foot stroke and hydraulic motor driven travel. The hoisting cylinder is mounted on a turntable bearing that can be rotated about 100 degrees by a hydraulic motor through a pinion and gear system for engaging and disengaging the gate lifting and latching mechanism.

Tetra Tech INCA provided final design services for LINK Light Rail Section S700: International District to Royal Brougham to the West Beacon Hill Tunnel. INCA was responsible for final structural design services for this light rail alignment, including aerial structures, transition structures, and embedded and direct fixation track slabs. This $55-million project was the first section of Sound Transit’s LINK light rail corridor to go to final design.

The structural effort included:

• Aerial structures and retaining walls including connections to the maintenance facility.
• Drilled shaft foundations in poor soil conditions with large seismic forces and a stringent two-level design criteria.
• Complex trackwork loads on the aerial structure (numerous turnouts and complex geometry).