Committee members in attendance:
The purpose of this meeting was to discuss any concerns, or clarify any issues, associated with the Preliminary Plans submittal.
Since the last meeting of the committee to discuss this project, the town has indicated that there is a need for the bridge to be able to carry 40,000 lbs. as the town has been, and will continue to, transport salt and sand trucks over the bridge. This led to discussion relative to the load rating table presented on page 2 of the plans. The load rating for the floorbeams in shear is listed as 9 ton. The consultant will investigate whether use of glu-lam can increase the load rating sufficiently. Also, the trusses had not been analyzed by Lichtenstein Consulting Engineers due in part to the general inherent strength of town lattice trusses as well as the relatively short span length. The report prepared for the bridge in 1995 by McFarland Johnson, Inc., however, did state that the truss should be able to carry 20 ton in like-new condition using a plate girder model analysis. It was agreed that Lichtenstein Consulting Engineers would analyze the trusses in detail. Analyzing the trusses will also help to determine how much rot can be tolerated in the truss members. At present, it is not anticipated that any lattice members will need to be replaced. John Weaver suggested taking some floor beam deflection measurements as well; the most meaningful measurements would be derived after removal of the existing distribution beams.
It was requested that consideration be given to replacing bolts at their connections with the chord with trunnels where they were trunnels originally. It is felt that this should strengthen the connections. General agreement that trunnels should be used where we can at the bottom chord connections.
Chris Slesar indicated that the area surrounding the bridge is very sensitive archaeologically. He would like to see the staging for the equipment needed for the substructure work to be on the road surface. There does not appear to be a problem with this.
Many different preservative/fumigant/color treatments are proposed for the structure. The bridge is currently painted red. NOCHAR can be pigmented, but this will mostly be used inside. There is another product, Andek, that is a fire retardant that can have color added. To obtain a paint-like exterior appearance, the clear coat must be topped with an opaque acrylic stain.
The preliminary plans show tongue and groove siding to replace what is presently on the bridge. It is not felt that tongue and groove siding is the original type of siding. Different types of siding were discussed. If planking is used, moisture content can be specified. General agreement that tongue and groove should not be used; Scott Newman will make recommendation on best system to use.
CONCLUSION: The consultant will re-analyze the floor system for use of glu-lam as well as the trusses. A summary will be prepared and distributed for comment to the committee members and others that were in attendance. Scott Newman will make a recommendation for the type of siding to be used. The town still needs to indicate if any type of lighting is desired on the bridge.
[This article was originally posted June 8, 2002]