Historic Bridge Committee Meeting

November 22, 2013

Warren Covered Bridge (45-12-15) Rehabilitation Project

The following is from the executive summary of the findings by DuBois & King Consultants and the VTrans inspection team presented at the meeting held in the VTrans Dewey Conference Room led by J.B. McCarthy, and DuBois & King Engineers, attended by the Historic Covered Bridge Committee members (including VCBS members John Weaver and Joe Nelson).

The Warren Covered Bridge . . . has experienced deterioration to several components, most notably the west abutment. Recent VTrans inspection reports have stated that the covered bridge roof is in need of replacement, bearing blocks have developed decay, and the West abutment has heavy concrete facing deterioration. The Town has received a Transportation Enhancement Grant to fund replacement of the west abutment and other necessary repairs.

DuBois & King has performed a site inspection, reviewed inspection records, completed a hydraulic and hydrologic study [and] developed construction cost estimates and identified a series of alternatives.

The results of the hydraulic and hydrologic study were that the existing bridge is sized to pass the 100-year storm with at least 1 foot of freeboard. The recommendations made for the rehabilitation of the bridge are:

• Replace west abutment with new exposed face with wingwalls on cast-in-place concrete pad on bedrock in existing abutment location
• Repair east abutment bearing seat cap by pumping grout under the base
• Fill scour hole at east abutment and repair cracks on the northeast wingwall
• Replace downstream west bank retaining wall in disturbance area
• Replace cedar shakes on north side of roof
• Replace bolster beam bearing blocks of main truss (12 total)
• Replace bearing beam bearing blocks (8 total)
• Replace 9-foot length, 4-foot height of siding at each of four corners of bridge
• Replace two rotted stringers at west end bay
• Evaluate capacities of decayed stringers to ensure load capacity, shave off decayed portions to prevent further moisture penetration
• Replace approach railing and signing

Because the total cost of all the improvements exceeds the Town's funding, DuBois & King will work with the town and VTrans to prioritize the improvements.

Note: The VCBS attendees recommended that the Town use steel standing ridge roofing rather than cedar because of the experience of the Town of Johnson losing their bridge to snow load: Cedar shingles do not shed snow readily.

For the complete DuBois & King project study, go to: http://www.vermontbridges.com/warren_covered_bridge_report_draft - november 2013.pdf.