Snow Hill Covered Bridge, Rockdale Indiana
Constructed in March of 1895, Snow Hill Covered Bridge is a fine example of a small-scale Howe Truss timber bridge. The Howe Truss was rarely used on Indiana wooden truss bridges; the more conservative Burr Arch type was the favorite of the most important builders. Only about 22 Howe Truss bridges are thought to stand in Indiana. Snow Hill Bridge was an important passageway to Johnson Fork Road, which leads eventually to the Cincinnati area, the biggest market for local farmers.
Snow Hill Covered Bridge uses a Howe Truss to bear loads up to 12 tons (current rating). The concept of the Howe Truss was invented by William Howe in 1840. As was often the case with the empirical design process used by engineers in the early 19th century, Howe built upon the ideas of others. He borrowed the use of diagonal members from the Long and Town Trusses, but strengthened the resulting lattice work with vertical iron bars which which also allowed members to be lighter. The Howe Truss has often been cited as a significant step towards all metal bridge construction. Indeed, it is interesting that the Snow Hill Bridge would have been erected using the Howe Truss as late as 1895. The 1890s were the heyday of the all-metal truss bridge in Indiana, although a good number of traditional timber bridges continued to be built in rural counties of Indiana, where successful builders were able to convince county commissioners of the practicality of their designs.
One might also note that the Howe Truss was very popular in Franklin County. Nearly all known vehicular spans in the county were Howe Trusses; several were built in the 1890s. The only other remaining wood bridge in the county today, the Stockheughter or Enochsburg Bridge, is also a Howe Truss span. It would appear that the county commissioners favored the Howe Truss. Whitewater Canal Aquaduct is also in Franklin County. Although not truly a bridge, but rather an aquaduct, it utilizes the Burr Arch Truss.
It would appear that Snow Hill Bridge was erected by local builders who had knowledge of the Howe Truss bridge type. According to County Commissioner's records, the substructure was started in October 1894 by John H. Horn, a local mason whose family owned property about one-half mile from the bridge on Snow Hill Road. William Butts, a local carpenter, erected the timber bridge with the help of area laborers. Work was completed in March 1895, the total cost being $1,422.50. Neither man is thought to have built any other timber bridges. The name of the bridge comes from Lemuel Snow, a Revolutionary War officer and owner of the high ground west of the bridge (Snow Hill).
Bridge Description
Snow Hill Covered Bridge, 1895, is located in Whitewater Township, Franklin County, in the extreme southeast corner of the county, only 1 3/4 miles from the Ohio-Indiana border. The bridge is also known as Johnson Fork Covered Bridge; this is how county commissioners' records refer to the structure. Area residents have long since used the name Snow Hill. Surrounding terrain is gently rolling and the bridge spans Johnson Fork, which merges with Whitewater River about 2 miles south of the site. The bridge carries Snow Hill Road across the stream and joins it to Johnson Fork Road on the east bank.
The Howe Truss type bridge rests on stone abutments with wing walls. Additionally, the west abutment was partly reinforced with concrete in 1929, and in 1987, concrete piers which reduce the effective span were placed about 10 feet from the abutments.
Snow Hill Bridge is an 8-panel, 75-foot-long Howe Truss structure. True to the Howe Truss formula, paired diagonal wood members slant in one direction while the sandwiched single member slants diagonally in the other direction. All double diagonals slant westward. Overhead X-braces are single members linking each top chord to the opposite top chord. A similar web of X-braces on the underside of the bridge links the bottom chords. Both top and bottom chords are composite members formed of sandwiched planks held together by iron nuts and bolts with washers.
The use of iron joining bolts and tie rods is common in the Howe Truss, and Snow Hill Covered Bridge is no exception. Paired vertical iron bars mark the upper and lower meeting points of the doubled and single diagonals (the division point between panels). Iron nuts and washers joining the verticals to the upper and lower chords allow the bridge to be adjusted if necessary. The vertical bars provide support in tension. Iron bars also link the top chords overhead, and the bottom chords underneath. Iron shoes are used to anchor the diagonal braces.
The gable roof has a slight overhang and the exterior walls are covered with vertical board and batten siding. The siding does not extend to the eaves, leaving an open clerestory across each flank of the bridge. Portals are plainly detailed, with a portion of the wood board and batten siding wrapping around to the first three or so feet of the interior walls. The upper corners of the portal opening are rounded. Portals have been painted white, while the flanks are barn red. Dates 1885 (incorrect) and 1987 (rehab date) are crudely painted in black on each portal gable end.
Since construction in March 1895, Snow Hill Covered Bridge has been altered several times. In 1928, openings were cut into each side for automobile traffic visibility. An elderly local farmer tells an anecdote that in 1929, he helped build a concrete abutment on the Snow Hill side of the bridge to strengthen the stone abutment. Mostly due to the openings cut through in 1928 exposing the trusses to the elements, but aggravated by missing siding and a deteriorated roof, the bridge had deteriorated by the 1980s. A truck carrying a bulldozer disregarded load limit signs and damaged the bridge in crossing in 1986. In the same year, the bridge was deemed unsafe and closed to traffic. With much community support, a restoration project was initiated. Several sections of lower chords had to be replaced. Six diagonal braces were replaced, and the contractor had to recast two of the iron diagonal member shoes. The flooring was replaced. Originally, it was a wide plank floor, now the floor is 2" X 4"s laid on edge. The siding was repaired with wood which matched the original poplar siding. A new asphalt shingle roof was installed. The abutments were sandblasted and repointed. New concrete piers were installed about 10 feet in from the abutments, increasing the load limit of the bridge to 12 tons. Lloyd Brown was the contractor for the repairs and Jim Barker of AECON Engineering was the engineer.
Looking from Johnson Fork (1994)
Looking from Snowhill side (1994)
