REVIEWED BLD2022-0479+STRUCTURAL OBSERVATION+4.14.2022_7.20.37_PM+2804140C �
civil & structural
engineering & planning
RECEIVED
Apr 18 2022 BLD2022-0479
ENGINEERING I CITY OFEDMONDS
DEVELOPMENT SERVICES
DEPARTMENT
STRUCTURAL OBSERVATION REPORT
Project: Flynn Residence Bridge Assessment
Purpose: Structural Observation
Location: Talbot Bridge, Edmonds, WA 98026
Date: October 8t", 2020
CG Project: 20320.10
Report: 1
Client: Todd and Christi Flynn
General Contractor: NA
Field Rep: Dennis Titus, PE, SE & Laura Stafford 1 REVIEWED BY CITY OF '
EDMONDS BUILDING DIVISION ;
PURPOSE AND SCOPE
Field representatives of CG Engineering was on site on September 15, 2020 to observe existing
conditions, gather information, take measurements, and verify the existing framing sizes and layout.
The information was then used to analyze the bridge for fire truck loading as required by the local fire
district.
EXISTING STRUCTURE
The existing bridge serves a (1) single family home. The existing structure is a 12ft wide by 18ft long
wood -framed vehicular bridge that spans over a small creek. The bridge consists of four (4) double 8x8
pressure -treated girders spaced to align with vehicle tires and 3x12 decking. A 6x6 curb is attached to
the decking at each side of the bridge.
ANALYSIS
Structural calculations for the bridge prepared by McMahan Consulting Engineers and dated 2/9/1983
were provided for our review. The original calculations evaluated the bridge for H2O truck live loading in
accordance with AASHTO 1983 Specifications. Our analysis evaluates the bridge under HS20 live load
conditions in accordance with AASHTO 2002 and per the recommendations provided by the local fire
marshal. The live load cases evaluated included: (A) single 24k axle; and (B) two 16k axles spaced at 4'-0"
apart. The decking has also been evaluated for wheel loading distributed per AASHTO Specifications.
RECOMMENDATIONS
1. Decking: Wood rot was observed in four (4) decking planks. Other deck planks appeared to have
previously been replaced. Our analysis determined that the existing decking is inadequate to
support the HS20 loading described earlier in this report.
• Replace the decking with new PT 412 DF Select Structural decking
Girders: The existing girders appeared to be in good condition at the time of our site visit and
appear to be adequate to support the proposed loading based on our analysis. The girders bear
on concrete abutments with sufficient bearing area for the proposed loading.
• When the decking is replaced, assess the top surface of the girders for wood rot.
250 4th Avenue South, Suite 200
Edmonds, WA 98020
ph.425.778.8500 1 f.425.778.5536
www.cgengineering.com
Flynn Residence Bridge Assessment
CG Project No. 20320.10
October 8t", 2020
Page 2 of 4
2/2020
DISCLAIMER
This observation is the professional opinion of CG Engineering PLLC based on the information available during this assessment or evaluation.
This report does not warrant or guarantee that all conditions were discovered at the time of the observation. This report was prepared subject
to the standard of care applicable to professional services at the time the services were provided.
250 4th Avenue South, Suite 200
Edmonds, WA 98020
ENGINEERING ph.425.778.8500 1 f.425.778.5536
www.cgengineering.com
Flynn Residence Bridge Assessment
CG Project No. 20320.10
October 81", 2020
Page 3 of 4
Photo 1-Bridge looking towards Talbot Road
Photo 2 - Bridge South Elevation
C �
ENGINEERING
250 4th Avenue South, Suite 200
Edmonds, WA 98020
ph.425.778.8500 1 f.425.778.5536
www.cgengineering.com
Flynn Residence Bridge Assessment
CG Project No. 20320.10
October 8t", 2020
Page 4 of 4
Photo 3 — Decking Wood Rot
Photo 4 — Girder Bearing Condition
C �
ENGINEERING
250 4th Avenue South, Suite 200
Edmonds, WA 98020
ph.425.778.8500 1 f.425.778.5536
www.cgengineering.com