Present at Meeting:
Sean James provided a PowerPoint presentation to supplement a previously distributed Engineering Study summary report. Following is a very brief summary - more detail can be found in the engineering report. Please note that since the October 24th meeting, the Town of Randolph was provided an overview of the report and issues and has indicated their position on some items. The major item is that the Town requests that the bridge be rehabilitated to support an H6 loading which has been agreed to by committee members. Updates are shown in italic print to reflect this.
Roof System: It is the intent to salvage the existing metal roof. It is assumed that approximately 8 rafters will need replacement and 1 will need repair. The roof boards appear to be in good shape with no action necessary. It is recommended that wood blocking be installed between the support beam and the top chord of the trusses at 16 locations adjacent to each kingpost for which there in no crossbeam. It is also recommended that additional'X' bracing be added along the top chord between existing crossbeams.
Truss System: Approximately 2 member of the north king post need replacement as well as 4 truss diagonals which have split ends to support the current H4 loading. As an H6 live load capacity will be accommodated, more replacement or strengthening - approximately 8 additional diagonal members - will be needed. It is estimated that approximately 10% of the chord members will need replacing. Some other repairs such as with epoxy and through bolts may be necessary. Some minor amount of siding may need replacement as well as the siding on the portals.
Floor System: Complete replacement of the decking with 3" x 8" planks is recommended. As the bridge will be rehabilitated for an H6 capacity, all the existing 4" x 10" floorbeams will be replaced with new Douglas fir 4" x 12 3/4" floorbeams. In addition, a new wood curb is recommended.
Substructure: Abutments are in good shape. Some repairs will be needed to the abutment stems and all 4 wingwalls. Remaining cracks should be sealed; graffiti removed and weep holes installed.
General: There is a dry hydrant located at the southeast corner. It is proposed that fire retardant and insecticide be applied. As well, a Protectowire system is recommended by the consultant but the Town has indicated they don't want this.
General Discussion: It was suggested that the Town be asked whether or not snowmobiles use the bridge; if so, runners may be warranted. Also, will curbing hinder the farmer who regularly uses the bridge? In that there is a very low traffic count and it doesn't appear that there is a need for the bridge to carry heavy vehicles (there aren't any homes on the other side of the bridge), there appears to be an opportunity to perform minimal repairs with no structural changes due to loading and traffic. In many cases changes are needed to meet current traffic needs, so this appears to be a good opportunity to minimize change and work. Nancy questioned paving the approaches – others agreed that it would alter the setting and is not desired. Also, does the curbing need to be treated? Opposition to the use of weathering steel guardrail was voiced. Some like it, other don't. Can we use steel-backed timber guardrail – not sure there is room for the posts. Could steel posts be used? Could decking be of oak? It will last longer. 4" x 8" decking was suggested.
It was agreed that an oak deck would be used with no runners. Also, no paving of the approaches. Non-treated curbing would be installed. Approach rail is needed but the type is still undecided.
Chair, Historic Covered Bridge Committee
[This article was originally posted February 9, 2008]