National Register adds Bynum Bridge to North Carolina Historic Places

Raleigh, NC – The Bynum Bridge in Chatham County was among the seven places in North Carolina to be added to the National Register of Historic Places. The Bynum bridge was among the properties reviewed by the North Carolina National Register Advisory Committee and was subsequently nominated by the North Carolina State Historic Preservation Officer and forwarded to the Keeper of the National Register for consideration for listing in the National Register.

Bynum Bridge 2020
Bird’s eye view of Bynum bridge (photo by Gene Galin 2020)

The listing of a property in the National Register places no obligation or restriction on a private owner using private resources to maintain or alter the property. Over the years, various federal and state incentives have been introduced to assist private preservation initiatives, including tax credits for the rehabilitation of National Register properties. As of Jan. 1, 2020, over 3,933 historic rehabilitation projects with an estimated private investment of over $3.043 billion have been completed.

Bynum Bridge, Bynum, Chatham County, listed 4/23/2020

Constructed between 1922 and 1923, Bynum Bridge is the longest unaltered reinforced concrete tee beam bridge remaining in North Carolina. It spans the Haw River at Bynum, a small rural textile mill village established in the 1870s, and formerly carried Bynum Road, once the primary route between the Chatham County seat of Pittsboro and the university town of Chapel Hill in Orange County. In 1952 a new bridge was constructed 500 yards upstream for US 15-501, bypassing Bynum. The old bridge continued to serve local traffic until 1999, when for safety concerns it was blocked to automobile traffic and used solely as a pedestrian bridge. Bynum Road remains a secondary road on either side of the bridge, designated SR 1713 on the east and SR 1871 on the west. The heart of the old village of Bynum with houses, church, and stores liesalong the hillsides above the East side of the bridge. The 1,000-acre Lower Haw River State Natural Area lines both sides of the river with public access and hiking trails on the East side. The county-owned Bynum Beach Access Area lies along the west side of the river near the approach to the bridge.

At its completion in May 1923, the bridge was considered state-of-the-art design and engineering. The reinforced concrete tee beam bridge has a length of 806.1 feet stretching across nineteen spans of about 43 feet each. Only one tee beam bridge in the state is known to have been longer, and it was built 30 years later and replaced in 2001, leaving Bynum Bridge the longest to remain. The deck has a width of 17 feet across three longitudinal beams, typical of the earliest tee beam bridges, and lies about 17 feet above the rocky riverbed below. The bridge has high integrity, retaining all of the major original elements of its tee beam form. This type of bridge was introduced to the state highway system in 1919 and used extensively until the 1950s. Tee beam construction entailed the casting of concrete abutments on either bank of a crossing, with freestanding cast piers placed up to 50 feet apart between the abutments if more than one span was required. Wooden formwork encasing steel reinforcing rods was assembled for pouring the superstructure, which consists of three or more longitudinal beams, a deck, and usually solid parapets flanking the sides of the deck (figure 1). These were cast together as one integrated unit for each span, supported by the abutments and piers. After the concrete cured, the wooden formwork was removed and used to construct the next span.

Bynum Bridge retains the original piers, beams, deck, and parapets in all spans. Like most tee beam bridges built purely for strength, safety, and durability, Bynum Bridge has little architectural adornment, with the exception of the recessed panels in the parapets flanking the roadbed. The road surface is asphalt.

The only noticeable alteration to the bridge has been the installation of handrails atop the flanking parapets, added as a safety feature when the bridge was converted to pedestrian use in 1999. Rows of five vertical metal bollards were placed at the approaches on either end as barriers to automobile traffic. An eight-inch water pipe is suspended alongside the south beam under the deck, installed prior to 1980 to connect the Chatham County water system with the Town of Pittsboro water system. This may be upgraded in the future to accommodate a large development planned south of the river, but will be done to respect the structural integrity of the historic bridge.

Named for the Saxapahaw (also called Sissipehaw) tribe of Native Americans who once lived along its banks, the Haw River rises in Guilford County, N.C., and flows southeast into Alamance County and then Chatham County where it joins the Deep River to form the Cape Fear River. The river has long been important to the history of the Piedmont region of North Carolina.

About 1860 the Bynum family built a flour mill on the Haw about six miles northeast of the Chatham county seat of Pittsboro. An 1870 map of Chatham County shows a bridge crossing the Haw at “Bynum’s M.” (Bynum’s Mill).

In 1872 brothers Carney and Luther Bynum founded Bynum Manufacturing Company to produce textiles, and the site developed into one of the many nineteenth century rural textile mill villages that harnessed the fast-flowing waters of the Haw and Deep Rivers in the central Piedmont. The road through Bynum was the principal route between Pittsboro and Chapel Hill in Orange County, home to the University of North Carolina. As seen in old photographs, by 1879 a major covered bridge with a latticed timber truss was erected at Bynum adjacent to the site of the present bridge.

Through the second decade of the twentieth century, counties were largely responsible for construction of most roads and bridges, with little coordination across county lines, and “the state became a haphazard patchwork of roads to nowhere.”With the introduction and proliferation of automobiles in the first decades of the century, road conditions were dire. Most roads were dirt or clay, and narrow wooden bridges were unsuitable for motorized traffic. In this period the number of licensed cars doubled every two years. In 1909 there were 1600 licensed vehicles in North Carolina, but by 1919 the number had reached 109,000.

The “Good Roads Era” of highway building in North Carolina began under Governor Locke Craig, elected in 1912, and in 1915 the state legislature established the State Highway Commission. The Federal Roads Act of 1916 provided increased funding for roads and bridges and promoted the adoption of standardized road and bridge designs nationwide. In 1919, the Good Roads Associationproposed a bill that would develop a network of hard-top roads to connect all the county seats and principal towns. The Doughton-Conner-Bowie Act of 1921 approved state control of approximately 5,500 miles of hard-surfaced roads in North Carolina, and called for linking the state’s 100 county seats, principal towns, principal state institutions, and the highways of adjoining states. In that year Governor Cameron Morrison and state lawmakers issued $50 million in bonds and a one cent gasoline tax to create a system of roads connecting counties, launching the first organized statewide road and bridge improvement campaign in North Carolina history. By 1927 $100 million in bonds were approved, and North Carolina emerged as the “Good Roads State.”

State Highway Commission engineers worked closely with the engineers from the federal Bureau of Public Roads. The first North Carolina Chief Bridge Engineer was William L. Craven, who served from 1917 to 1944. Prior to taking the post, Craven had fifteen years of experience working with bridge companies in Pennsylvania, Virginia, and North Carolina.

The construction of Bynum Bridge was made possible as a result of the 1921 bond issue. The bridge was part of North Carolina State Project No. 99, which created State Route 175, later to become US 15-501, connecting Pittsboro to Chapel Hill. The bridge itself was State Project No. 400. R.M. Walker and Company from Atlanta, Georgia was awarded the $50,000 contract with Chatham County to construct the bridge. The project was designed and overseen by staff of chief bridge engineer William L. Craven of the NC State Highway Commission. The Chatham Record from March 10, 1922 recorded this contract: “Contract Let – The contract has been let by the county commissioners for the building of the Bynum Bridge over the Haw River on the state highway, which is to be concrete reinforced with steel. The contract was let to a bridge force of Atlanta, GA., and was let for $50,000. Work will begin about the first of April.” The firm broke ground before June 16, 1922 and completed the bridge on May 18, 1923. A photograph made during construction shows the west end of the bridge nearly abutted the 1879 covered bridge, which was removed soon after completion.

The bridge was the primary crossing over the Haw River at Bynum for 30 years. By 1936 old State Route 175 was designated US Highway 15-501.14 As traffic increased, the N.C. Department of Transportation made plans to reroute US 15-501 to a newer bridge over the Haw. By modern standards, Bynum Bridge was considered only one and half lanes wide. In 1952 a new bridge was erected 500 yards upstream for a rerouted US 15-501, within sight of Bynum Bridge. Local traffic continued to use Bynum Bridge until 1999, when NCDOT determined the bridge’s concrete and steel reinforcement were eroding, and recommended the bridge be closed.

The cost of a new bridge was considered unjustified because of the relatively low volume of traffic and the nearby alternative crossing on US 15-501.15

After much public debate regarding fate of the old bridge, ultimately NCDOT agreed to keep the bridge open for pedestrian use. The presence of the water pipe suspended from the bridge connecting the county and Pittsboro water systems, and the likely cost of its relocation, appears to have been a factor in the decision.16 Vehicle barriers were added at either end, and a railing placed atop the flanking parapets as a safety feature. It remains under the ownership of NCDOT.

With its proximity to the Lower Haw River State Natural Area and the county-owned Bynum Beach Access Area, the bridge has since become a focal point for nature-related activities and special gatherings and events for people in Chatham County and beyond. It is much used and enjoyed by pedestrians, cyclists, wildlife observers, walking groups, families and stargazers. Many well-attended public events take place on Bynum Bridge. Several stargazing groups including the Chapel Hill Astronomical and Observational Society and the Bynum Astronomy Club use the bridge as an ideal gathering place to search and enjoy the dark skies. The National Audubon Society reports that of the many bird watching areas in the N.C. Piedmont, “few are better than the Bynum Bridge area in Chatham County.”

Bynum bridge pumpkin (photo by Gene Galin)

The Bynum Bridge Fest is an annual art show where local artists can sell their work on the bridge. “Pumpkins on the Bridge” in October is a much beloved annual event that features hundreds of carved and candle-lit Jack-O-Lanterns placed on the bridge from dusk until midnight. A community potluck meal is held on the bridge every 4th of July. Bynum Bridge is a favorite site for photographers, painters, musicians, writers and other artists.

Bynum bridge art (photo by Gene Galin)

It is somewhat ironic that Bynum Bridge, which was built to serve communities with increased automobile traffic, has become a favorite spot for residents to get away from traffic and experience a connection to nature. Since it is handicap accessible, the bridge allows everyone this opportunity. Although Bynum Bridge no longer serves as a major transit point between county seats, it still connects communities and people, and helps connect all with the beauty of nature. Generations have stood on Bynum Bridge daydreaming, wishing, thinking, working out a problem, sharing a romantic moment or simply watching the Haw River roll on toward the sea. As one Bynum resident noted, “That river has heard lots of laughter and carried away many a tear.”

Reinforced Concrete Tee Beam Bridges in North Carolina

With the exponential growth of motor vehicular traffic in the second and third decades of the twentieth century, transportation agencies at all levels of government sought methods, designs, and materials for roadway and bridge construction that would accommodate rapidly increasing volumes of traffic and provide safety, durability, economy, and relatively quick construction. Though concrete has been in use since Roman times, the late nineteenth century saw the introduction of reinforced concrete for many types of structures, with steel rods embedded in concrete for additional strength and increased length of spans between supports. By the 1910s, advances in engineering led to a variety of standardized concrete bridge designs promoted by the federal Bureau of Public Roads (later the Federal Highway Administration) for federal-assisted highway projects. State agencies like the North Carolina State Highway Commission, founded in 1915, often copied or adapted federal designs for state projects as well as those receiving federal assistance.

One of the most popular designs for reinforced concrete bridges was the tee beam, which has cast-in-place, longitudinal concrete beams with integral concrete deck sections across the tops of the beams. The beams, deck, and parapets flanking the deck are poured together as a unit within wooden formwork assembled on site, which is removed when the concrete cures. The beam-and-deck superstructure rests atop vertical concrete abutments and piers that are cast separately in advance. In cross section the beams are deeper than their deck sections, which produces the T-shape that gives them their name. The first designs consisted of three longitudinal beams (Bynum Bridge has three beams), but by the late 1920s the standards were updated for wider roadways, and later examples usually consisted of four or more beams. They were generally used for single spans 25 to 60 feet long, but multiple spans allowed for the construction of much longer bridges. The Federal Highway Administration classifies tee beams as type 104, with the “1” indicating reinforced concrete, and “04” the tee beam configuration.

Tee beam bridges were first used in the North Carolina about 1910 by counties, cities, and railroads. The form became one of the most commonly used State Highway Commission designs, with standard plans first prepared in late 1919. Hundreds of tee beam bridges were built along highways across the state between 1920 and the 1950s. The great majority were of four or fewer spans of less than 250 feet in length. The tee beam was a popular design because it was more economical for lengths in excess of 25 feet than were concrete arch or slab bridges. But like all cast-in-place concrete bridges, tee beams were labor intensive owing to the requisite wooden form work and they had increasingly high labor costs, especially for multi-span bridges. By the early 1960s the N.C. Department of Transportation was phasing out the tee beam in favor of prestressed concrete beam bridges and other designs.

An inventory of historic bridges on the North Carolina highway system was completed in 2005. Of 5,057 bridges included in the survey, 795 were identified as tee beam bridges constructed between 1920 and 1960. Of these, almost 200 were built by 1923. Other tee beam bridges may have existed that were removed before the inventory, and some included in the inventory have since been removed, but the project database provides a picture of the extent and variety of tee beam construction in the state. Bynum Bridge was not included in that inventory, apparently because it had been closed to vehicular traffic in 1999. But the inventory reveals the status of Bynum Bridge in the era of tee beam construction.

At 806.1 feet, Bynum Bridge was by far the longest of the first generation of tee beam bridges built before 1924, of which only one other is known to remain that exceeds 500 feet. The inventory indicates it was the second longest ever constructed, surpassed only by a White Oak River Bridge (#660030) of 875 feet at Swansboro in Onslow County, constructed in 1952 at the end of the era of tee beam bridges. That bridge, and a sister tee beam bridge of 768 feet (#660025) constructed at the same time and connected by an island in the White Oak River, appear to have been replaced or heavily overbuilt in 2001. The closest known competitor that still stands is the French Broad River Bridge at Hot Springs in Madison County, at 527 feet in length, built in 1951. For its age, length, and high integrity, Bynum Bridge is eligible at a state level of significance as North Carolina’s most prominent example of an important early twentieth century bridge type.

Source: National Register of Historic Places Registration Form