Specifications include, but are not limited to: Building a Bicycle/pedestrian bridge in the Northgate area of Seattle. The bridge will over cross I-5 along N/NE 100th Street. The base bid project will also provide a spur connection bridge overcrossing 1st Ave NE that connects to the Sound Transit Light Rail Station. A multi-use trail connection west of I-5 is included in the base bid. Base bid work includes temporary traffic control, earthwork, asphalt paving, concrete and steel bridge construction, retaining walls, drilled shafts, storm drains, detention pipe, landscaping, wetland mitigation, concrete curbs, driveways, sidewalks, curb ramps, signing, channelization, lighting, handrails, and signals. The additive involves bicycle and pedestrian improvements on 1st Ave NE. The Additive work includes temporary traffic control, earthwork, asphalt paving, curb and gutter, sidewalks, curb ramps, signing, channelization, lighting and signals.