National Register Nomination Information:
The Stone Arch Bridge spans Mink Brook with a radius of 17 ½ feet. The vault, 24 ½ feet wide, is constructed of random granite rubble laid with a relatively tight and consistent mortar joint. The arch voussoirs are rock-faced ashlar measuring approximately 12 inches by 18 inches high with varying thickness or depths of the individual stone pieces.
It is not known conclusively if the 6 inches thick concrete caps that top the span's stone side walls are original to the structure or not. Presently the assumption is that they are not, and that they are instead more recent alterations made in an attempt to protect the masonry from weather and its destructive side effects. This assumption is based in part upon the knowledge, gleaned by old photographs, that the "sister" bridge to this one that spanned Mink Brook on the West Lebanon Road had masonry side walls capped only with flat surfaced granite blocks about 6" thick. Older area residents do not recall the concrete being original to the walls, rather recalling only flat stone pieces. Also, because there was no concrete used in this bridge's structural construction, unlike the sister bridge's reinforced concrete arch, it seems highly unlikely that concrete would have been introduced strictly for making caps to top these old two side walls. Other than the apparent addition of these concrete caps, and the obvious paving of the road many years ago, the bridge presents itself as originally designed and constructed.
STATEMENT OF SIGNIFICANCE
The Great Hollow Road Stone Arch Bridge is eligible for the National Register under criterion A for transportation. It possesses integrity of location, setting, design, workmanship, materials, feeling, and association for the period 1914-1946, the date of construction to the 50-year cut-off. This durable and cost-effective bridge was constructed at a time when the Selectmen were coping with the need to replace the Town's aging wooden bridges with structures of greater permanence able to carry the increased loads of the automobile age. In addition, this crossing is an important one linking the Etna/Hanover Center/Mink Brook Valley with urban Lebanon. It is one of the only two stone bridges in Town, the other being a 19th Century bridge of pier and lintel construction.
By the second decade of this century, the effects of the newly dawning automobile age were already starting to be felt on the nation's highways and bridges. Hanover, like most rural communities, was no exception and Town records from this period indicate that the Town's Selectmen were grappling with the problems of the community's aging wooden bridges and the increasingly heavier loads that were being placed on them. The 1915 Hanover Town Report, written after several of the major bridges on principle roads into Town had been replaced during the summer of 1914, summed up the situation well:
"The two bridges over Mink Brook on main highways, had long been in a poor condition. The requirements of modern automobile travel, road rollers, Standard Oil Co.'s wagons, and the unknown requirements for traction engines in the future called for unusually wide and strong bridges. The foundation and abutments of the old bridges were only of dry masonry, had been heaved by frost and were in such bad shape that entire rebuilding was necessary from the bottom up. The problem was to get permanent bridges, good for all the future, if possible."
Until comparatively recently, the principle highway access into Dartmouth College and the Hanover village area, coming from the south, was not present day NH Route 120, but rather Great Hollow Road coming from Lebanon, and then the Greensboro Road west to Lebanon Street. This route required crossing over Mink Brook immediately south of the Great Hollow Road's intersection with the Greensboro and Etna Roads.
With all this in mind, the Town Selectmen chose to simultaneously replace both the above referenced bridge, and the comparably aging structure crossing Mink Brook on the so-called West Lebanon Road (now NH Route 10), during the summer of 1914.
Wooden replacement bridges were ruled out of the question by selectmen because of their lack of durability and maintenance costs. Therefore, the Town decided to receive cost estimates for spans constructed of heavy plate steel girders with concrete floors and abutments, a truly state-of-the-art bridge design for that time. However, this type of construction was determined to be out of the realm of possibility due to the high costs and tight local budget.
Because Dartmouth College was offering the Town, free for the taking, the massive pieces of cut stone from the foundations of an old bank building that they were demolishing on North Main Street, the Selectmen then chose to consider constructing two stone arched bridges, one of the West Lebanon Road and the other on Great Hollow Road, both crossing Mink Brook. Once again, the Town took prices for the proposed work from outside contractors, and the price was still determined to be too high.
Therefore, the decision was made to employ local labor and talent, with the Town acting as its own contractor. As mentioned previously, the two spans were replaced during the summer months of 1914. The West Lebanon Road Bridge ended up costing a total of $3,171.50 and was constructed of dressed stone facing a 28 foot reinforced concrete arch. The Great Hollow Road Bridge cost less at $2,193.08, and was constructed totally of stone. The 1915 Town of Hanover Annual Report provides a detailed record of the cost of both bridges, as well as a brief report of the discussion by the Board of Selectmen that brought the new bridges into being, titled "The Stone Bridges."
Of the two bridges, the West Lebanon Road span was short lived. In 1940, the State of New Hampshire relocated to the east and straightened that section of the road that runs across the lower area of Mink Brook and its meadows. The construction drawings dating March 2, 1940 called for its removal and a new stone bridge constructed approximately 100 feet easterly of the old road. Today, not a trace of the old span remains.
On the other hand, the Great Hollow Road Bridge was far more fortunate. In the years following its construction, what is now referred to as NH Route 120, or locally known by the name Mount Support Road, became the primary road between Hanover and Lebanon. As a result, the overwhelming increase in traffic volumes that have occurred in recent years has not dictated this bridge's destruction and replacement. Hence, the structure remains not only as a remnant from early years of the automobile age, but also as an example of a type of bridge construction not very common even when originally constructed more than 80 years ago.
MAJOR BIBLIOGRAPHICAL REFERENCES
Town of Hanover Annual Report, 1915
A History of the Town of Hanover, N.H.; by John King Lord; The Dartmouth Press; 1928
Hanover, New Hampshire, A Bicentennial Book; Essays in Celebration of the Town's 200th Anniversary; Edited by Francis Lane Childs; Hanover, 1961
FORM PREPARED BY:
Frank J. Barrett, Jr., Town of Hanover Code Administrator
Town of Hanover Municipal Building
41 S. Main St., P.O. Box 483
Hanover, NH 03755
DATE ENTERED: March 11, 1996
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