Starrucca Viaduct
Part of one of the earliest major railroad links between the Eastern seaboard and the Midwest. It spans Starrucca Creek at Lanesboro in northeastern Pennsylvania. It is 1,040 feet long from abutment to abutment, about 90 feet above the ground and about 25 feet wide at the top. The bridge has 17 semi-circular arches of 50-foot diameter supported on slender piers. Downward from the smallest cross section at the root of the arches, the piers increase in width both parallel and transverse to the direction of traffic. The thirteen full-height piers are supported on concrete spread footings three feet thick. The footings bear on hardpan at a depth of no more than 9 feet below the ground surface. For the three shorter piers at the ends of the bridge, the stone masonry was laid directly atop the surface of the hardpan. The piers and the arches are built of stone. The arches support outside parapet stone walls and three inside parallel longitudinal brick walls. In turn, the five walls carry the bridge floor including a flagstone base and ballast.
The viaduct was designed by Julius W. Adams and built by his brother-in-law, James P. Kirkwood. First class railroad builders, they came from different backgrounds. Kirkwood, born in Edinburgh (Scotland) in 1807, completed his formal education by the age of 12 and two years later was apprenticed to a surveyor who founded a firm with a large practice serving railroads and canal interests. At 25, Kirkwood moved to the United States where he soon became a resident engineer on railroad construction in western Massachusetts. Adams was born in Boston in 1812 into the family of presidential fame. He won an appointment to West Point but resigned after two years to work on the construction of the Paterson & Hudson River Rail Road in New Jersey. In the ensuing years both Kirkwood and Adams participated in the building of several rail lines. In later years both settled in Brooklyn and developed consulting practices in new branches of civil engineering: water supply for Kirkwood and sewage systems for Adams. Both were founders of ASCE and served later as ASCE presidents, Kirkwood as the second and Adams as the sixth. The viaduct was located on the New York & Erie Railroad, a project that promised to open up a broad, virtually untapped corridor between the existing railroads and canals of Pennsylvania and New York. After ground was broken in 1835, repeated delays caused the real work on the 445-mile line from Hudson to Lake Erie to get underway only in 1846. The construction of the viaduct was started in the spring of 1847 and a contract with Messrs. Beard & Collins to build the viaduct was dated August 7, 1847. The job was to be completed by the end of 1848. The contractors showed so little energy or appreciation of the magnitude of the task to finish within one year that the job was taken from them in the spring of 1948 and turned over to Kirkwood who was hired by the Erie as superintendent of the construction. Kirkwood took the job with the understanding that time was of essence and cost was no object.
To cross the Starrucca Valley, a massive fill was considered at first with a stone arch over the creek, but good borrow pits were unavailable because much of the area was underlain by hardpan. A stone viaduct was decided upon, made of rubble laid in beds of cement mortar since the countryside abounded in flat stone about 3 inches thick. When a quarry a few miles up the Susquehanna Valley was opened Adams learned that blocks of stone 9 to 18 inches thick could be had in quantity, and adjusted his plans accordingly. A track ran 4 miles up the Starrucca Creek from the viaduct site to the quarry from which came most of the stone used in 1848. The remainder was hauled from other quarries by wagon. The material was fine-textured gray sandstone, locally called bluestone. It was laid in mortar made of Rosendale cement mixed with sand and lime. This natural cement came from a works opened in 1828 at Rosendale, New York.
The labor force in May 1848 is said to have numbered about 800. To finish the viaduct in a single season, the false work was largely built ahead of time, a full set of wooden centering was made for every arch, manpower and equipment were provided in excess, and the entire plant was kept in first-class working order to the placing of the final stone. In time the false work for the viaduct ña combination of trestle, scaffolding and arch centering ñstood 90 to 100 feet above the valley. A large quantity of the lumber was provided by a local businessman and a large number of small operators were engaged by Kirkwood to cut stone and lay masonry. The first locomotive crossed the viaduct on December 9, 1848 and the official inauguration took place after Christmas. Nearly two and a half years later the railroad was finished to Lake Erie. The inaugural excursion left New York on May 14, 1851, with President Millard Fillmore, Senator Daniel Webster and other dignitaries among the participants. At Susquehanna Depot, sixteen locomotives saluted the party with their whistles. Today, said Webster when the excursionists stopped at Elmira for the night, the locomotive has overcome mountain steeps and walked over the tops of forest trees. Tomorrow it will climb other hills, cross other valleys, and, at last, rest by the waters of Lake Erie”. Originally, the viaduct carried one track of broad 6-foot gage placed on 3 feet of stone ballast over the flagstone. As the time went on, the gage was changed 10 the standard 4 feet 8 1/2 inches, the surfacing above the flagstone waterproofed and increased in overall thickness, and a second track added. The size of the locomotives crossing the structure increased from 15 1/2 tons to the maximum of 422 1/2 tons. Major maintenance items required pointing of joints and, in 1961, sandblasting of the entire structure. After a century and a half of service, the viaduct continues to serve its original function and is expected to do so into the foreseeable future.
The superstructure of the aqueduct is supported on parallel wire cables, one on each side of the bridge, seated on cast iron saddles mounted on squat stone towers that stand about four feet above the top of the trunk described below. Each of the 8 1/2in-diameter cables is composed of 2,150 wrought iron wires spun in place and anchored to eye bar anchor chains. The chains are encased in cement grout to exclude air and moisture and thus prevent rusting, and embedded in stone masonry anchor blocks. The cables are wrapped continuously with a tight fitted wire. The flume was of heavy wood construction holding about 6 feet of water. It was 17 feet wide at the bottom, 19 feet at the water line and 20 feet at the top. Its sides were built up of two thicknesses of 2 1/2 inch untreated white pine plank, laid tight on opposite diagonals and caulked up to the waterline, in effect forming rigid, solid lattice-trussed webs. The floor was of double plank placed on transverse double floor beams which hung from 1 1/4 inch-diameter wrought iron rods.
These suspender rods doubled over the cables in stirrup form, and their bottom ends were threaded for the floor beam nuts. They were supported on the cables by means of small cast iron saddles clamped to the cables and prevented from sliding by spacer bars where needed. An 8-foot towpath was cantilevered out from each side of the flume, level with its top. The stiffness of the woodwork, including the flume and the two towpaths, was such that it was capable of sustaining its own weight, leaving the cables to carry their own weight and the water load. The aqueduct superstructure was 535 ft long, with three spans of about 131 ft and one of about 141 ft. Its flume was wide enough to accommodate boats of 130-ton capacity. Placed in service after the last deepening and widening of the canal was completed in 1852, these large boats had the advantage of being river worthy, thus eliminating the need for transshipment on reaching the Hudson. The last boat moved over the waterway in 1898. The Delaware River aqueduct was then purchased privately and converted into a highway bridge. A fire in 1932 destroyed the woodwork on a portion of the structure. A simple floor system was substituted and the toll bridge reopened to the public, giving over four decades of further service. Faced with mounting maintenance costs, the last private owner closed the bridge and in 1979 sold it to the National Park Service. After temporary repairs, the bridge was reopened to pedestrians in 1980. Studies of the soundness of the structure preceded a more permanent rehabilitation which also restored the basic historic aspects of the bridge. The permanent rehabilitation was completed in 1995 and the bridge was reopened to vehicles.
