Historic Structures

Livermore Truss Bridge, Wilton New Hampshire

Date added: September 15, 2016 Categories: New Hampshire Bridges

The Livermore Bridge is the only known example of a timber, half-through, pony lattice truss in North America. Crossing Blood Brook at an almost north-south axis, the 52' -3" long bridge, measured from outside edge to outside edge of the truss siding, forms a dangerous "T" intersection with State Route 101. The abutments are irregular granite blocks. Granite faced concrete wings dating to the 1990s project from the old abutments and support the bottom chords. A dry-masonry ramp made of mid-sized granite boulders supports the Russell Hill approach.

The approximate dimensions of the truss sheathing, exclusive of the galvanized standing seam "roof covering, are 8'-l 1" x 2'-3-l/2". Because the standing seam metal "roof and the vertical siding both protect and conceal the top chords, it is not possible to determine if the top chords are identical to the four 3" x 12" bottom chords. Lattice members are 3" x 10" with two 2" diameter trunnels per web intersection. Three trunnels secure the connections at the bottom chord. A distinctive feature of the bridge is the middle chord, consisting of two 14-3/4" -15-3/4" x 3" planks that support 6" x 12" x 20' deck beams. Numerous close, but unevenly spaced, 3" thick stringers support the 16'-1" long deck planking. The two systems, namely knee braces and lower-lateral bracing stabilize the structure against racking and horizontal sway. Knee braces, with bird's mouth notches on one end to accommodate the bottom chord and toe nailed into the deck beams on the other end, are approximately 3" x 6" or a bit smaller. The lateral bracing system is made of 1" diameter wrought-iron rods with forged eyes and rings.

Except for the loss of a section at the northwest end of the bottom chord caused by rot and an epoxy and steel-plate repair, the visible sections of the bridge seem in remarkable condition.

The bridge is currently posted for 6 tons and restricted to passenger vehicles. Russell Hill Road is being rerouted to a new crossing substantially downstream. The new bridge will permit emergency vehicle access to a new development project along Russell Hill Road without replacement or substantial alterations to the Livermore Bridge.

Inspection of the bridge yields limited insight into the confusion over the extent of Turtle's 1937 work. As is often the case with timber bridges, the planking, stringers, deck beams, and knee braces, being intentionally expendable, are of comparatively recent vintage. The lattice members possess a remarkable uniformity of finish and show no evidence of repairs. This might be attributed to an initial or subsequent creosote treatment. This uniformity also raises the possibility that they are Tuttle's work and not reused from an earlier structure damaged by flood. On the other hand, the innermost timber of the upstream middle chord does have a different finish (perhaps it is unplaned or cut with a vertical saw) suggesting either a different source or a replacement.

The history of the Town lattice has been documented extensively elsewhere. Patented in 1820 by Ithiel Town, the lattice truss bridge type uses a network of diagonal planks pinned together at their intersections and further secured by horizontal chords of the top and bottom of the truss. Pinned connections eliminated complicated joint carpentry found in other types of timber bridges. The high structural redundancy of the Town truss reduced loads in the individual members and had the additional advantage of distributing loads throughout the structure in case of local failure. Lattice trusses in timber were widely used in New England, and metal versions were popular Europe.

In light of the properties of the Town lattice, a carpenter of Tuttle's extensive experience should not have had particular difficulty constructing or repairing the Livermore Bridge. It is an open question whether he designed it or copied the remains of a damaged bridge. New Hampshire had many examples of lattice trusses available for his inspection in 1937. The Boston and Maine Railroad built the three other surviving ponies in New Hampshire. Further research may show whether the Livermore Bridge is a rare survivor of a once common type or a rare survivor of a rare variant of a common type. Whichever the case, the Livermore Bridge is the only remaining highway timber pony truss in New Hampshire.

Marjorie Standish Moors, nee Devlin, was a remarkable person. More than a widow of a Boston stockbroker, more than one of the many "summer people" with second homes in Wilton Center and the Town of Wilton in general, she took an active interest in the people and community around her. On her death in 1962 she left substantial bequests to long-term staff of her Wilton Center estate, the First Unitarian Congregational Church of Wilton Center, and numerous animal charities.

While such interests may have been common or even expected of a widow in her position, Moors also took an interest in the crossroads just below Wilton Center where she owned property. In the eighteenth, nineteenth, and probably well into the twentieth century, two roads ran down the hill from Wilton Center and crossed what is now called Blood Creek. From there the road, now known as Russell Hill Road, ran along the heights in early New Hampshire fashion to what are now the Towns of New Ipswich and Greenville. In the late 1700s, Rev. Jonathon Livermore built a dam and a sawmill just above the Blood Creek-Russell Hill Road crossing. Besides her role in the bridge, Moors also preserved the sawmill and had its masonry dam repaired after the floods of 1936.

The newspaper accounts and town reports are tantalizing, but unclear, about the extent of the work on the Livermore Bridge that Mrs. Moors financed. The Milford Cabinet, quoted above, speaks of "rebuilding" and "preserving," but town records speak of "bridge construction." When it comes to fiscal expenditure, the records are clear: Fred Tuttle and Nehe Pajanen were paid $3278.11 and $224.05 for labor and materials, respectively.

Tuttle, a WWI Army veteran, was a carpenter like his father. Together with his brothers, he built many houses in Hillsborough County, New Hampshire. His heirs sold his house and disposed of his papers, so the extent of his bridge building work remains unknown. Whether he repaired or built de novo, Tuttle left a remarkable structure worthy of a century of lattice bridge construction and of Moors' benefaction.