DuBois & King designed the replacement of an existing steel stringer bridge supported on one stone and one concrete abutment. Replacement design included load determinations and development of prestressing strand configuration for the new pre-stressed, precast concrete beams. Performed calculations and cost estimates and provided preliminary and final design, and construction phase services.
West Cove Bridge
D&K conducted a visual inspection of a two-lane, circa 1978 steel beam bridge with a covered sidewalk. The existing laminated timber deck structure is supported by concrete abutments on piles, spanning 69 ft over Eastman Lake. Field inspection included a complete visual inspection of all accessible bridge components. Measurements and photographs recorded existing conditions and D&K engineers noted observed deficiencies. We completed a review of existing engineering drawings and inspection reports for the current structure, as provided by Eastman Community Association (ECA). D&K completed an inspection report, complete with color photos and construction cost estimate, including conclusions and recommendations for short- and long-term improvements to deteriorating steel beams and eroding abutments. ECA decided to replace the deck and retain the steel beams and abutments.
D&K prepared contract drawings detailing replacement of the existing timber deck with a new glue laminated timber deck. The project required cutting and moving the existing covered walkway several feet to make room for construction of the new deck.
Professional Services
Field inspection
Review of existing data
Preparation of a Recommendations Report
Cost estimates
Preparation of contract drawings
Construction observation
Laconia Main Street Bridge Rehabilitation
Professional engineering services to evaluate existing conditions, repair, and replacement alternatives for the Main Street Bridge, the primary crossing over the Winnipesaukee River and predominant access in and out of the downtown area. The bridge consists of three distinct and separate bridge structures that each carries a City street (Beacon Street East, Main Street, and Beacon Street West). The three streets and bridge structures converge at a point to make one overall bridge structure at the street intersections. The Beacon Street East segment is a 137-ft, 80-ft-wide curved bridge, constructed in 1968. The Main Street segment is a 75-ft by 69-ft-wide structure, constructed in 1970. The Beacon Street West segment is a 137-ft, 70-ft-wide, curved bridge, constructed in 1968.
Services include: topographic survey and preparation of a base map; sampling of paint to be tested for lead; determination of needed repair or replacement for structural items; collection of data for two other area projects to evaluate recommendations and impacts on pedestrian safety, access, and egress; preparation of a Project Review and Compliance form; a bridge type study; evaluation of operation and equipment of the existing traffic signal at the Main Street-Beacon Street and the Main Street-Court Street intersections; engineering study; and preparation of preliminary and final bridges plans, estimates, and bid documents.
Recommended repairs include removal and replacement of the concrete decks and fixed and expansion bearing plates, cleaning and painting of all steel surfaces, repair or replacement of deteriorated stringers and concrete abutments and piers, replacement of all deck expansion joints and substandard bridge rails, and addition of new approach rails.
Mill Road Bridge and Retaining Wall
Engineering, permitting, and construction-related services for design-build bridge and retaining wall project. Bridge is an 83 ft long, single span, steel beam bridge with a concrete deck supported by concrete abutments. Steel beams were cleaned/painted. High performance concrete deck replacement, elimination of curbs, and new abutment backwalls and railings significantly extend the service life of the structure. New deck designed to support AASHTO HL-93 live loads and bridge improvements designed in accordance with VTrans bridge design criteria. Designed of new 110 ft by 15 ft tall cast-in-place concrete retaining wall supporting a portion of Mill Road roadway approach. Design for reconstruction of 300-ft of roadway approach.
Ryegate Design-Build Culvert Replacement
D&K is the lead engineer for the $15.2 million dollar VTrans Ryegate STP CULV (10) design-build project, which replaces a deteriorated culvert conveying the Manchester Brook under US Route 5 and the Washington County Railroad. The existing undersized culvert has contributed to flooding of US Route 5 and the backwater jeopardizes the integrity of the roadway and rail embankments. The existing culvert is a deeply buried structure (over 60 ft under the railroad embankment) with steep embankments on both sides of the roadway and rail line. Partnering with the contractor, D&K has developed a solution that provides savings in initial construction costs, safer conditions for future inspections, better access for maintenance, improved aquatic habitat, and improved service life and constructability.
The structure consists of two 32-ft-wide, cast-in-place, reinforced concrete arch culverts beneath the roadway and rail line. The culverts are 141 ft and 128 ft in length and will have a 100-year service life, eliminate flooding potential, and greatly improve aquatic organism passage. The project includes a temporary rail bridge to allow culvert excavation below, and temporary track realignment and superelevation removal to minimize lateral forces of trains on bridge throughout construction. Complex design issues include designing a culvert to meet better than a 100-year service life; design of support for temporary roadway and rail bridges; design for significant slope stability issues; protection of the brook throughout construction; and limiting settlement between footings to 1 inch or less.