The Gilpin's Falls Covered Bridge is a Burr arch through truss

Burr Truss

The Burr Arch Truss — or simply Burr Truss or Burr Arch — is a combination of an arch and a multiple kingpost truss design. It was invented in 1804 by Theodore Burr, patented on April 3, 1817, and used in bridges, usually covered bridges....

 wooden covered bridge

Covered bridge

A covered bridge is a bridge with enclosed sides and a roof, often accommodating only a single lane of traffic. Most covered bridges are wooden; some newer ones are concrete or metal with glass sides...

 near North East

North East, Maryland

North East is a town in Cecil County, Maryland, United States. The population was 2,733 at the 2000 census.-History:The Turkey Point Light Station was listed on the National Register of Historic Places in 2002...

, Cecil County

Cecil County, Maryland

Cecil County is a county located in the U.S. state of Maryland. It is part of the Delaware Valley. It was named for Cæcilius Calvert, 2nd Baron Baltimore , who was the first Proprietary Governor of the colony of Maryland from 1632 until his death in 1675. The county seat is Elkton. The newspaper...

, Maryland

Maryland

Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

, United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. The bridge was constructed by local Cecil County bridgewright Joseph George Johnson in the autumn and winter of 1860/61 across Northeast Creek. The bridge was erected adjacent to and upstream of Samuel Gilpin's mills and dam and crosses the millpond formed by it. This bridge has a span of 100 feet and a total length of 119 feet with its shelter panel overhangs, is 13.5 feet wide and is closed to all vehicular traffic.

The structure was restored in 1959 by the State Roads Commission and the Historical Society of Cecil County. In 2010 the bridge was rehabilitated by Engineers: Wallace, Montgomery & Associates LLP, Kinsley Construction, and specialist bridgwrighting subcontractors, Barns & Bridges of New England, The Truax Timberwright Woodworks and New World Restoration

Gilpin's Falls Covered Bridge was listed on the National Register of Historic Places

National Register of Historic Places

The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...

in 1978.

Construction Details

The Gilpin's trusses, floorbeams, ties and lateral bracing systems are framed almost entirely of Eastern White Pine. (Pinus strobus) A species typically favored for wooden bridge framing in areas of the country where it was found, for its strength to weight ratio. So favored for this purpose, it was commonly imported into areas where it was unavailable as an indigenous species, (minimizing dead load a strategy for increasing capacity for live load) Original rafters were quite easily identifiable from those replaced after the 1958 roof collapse, and were (as are the newly replicated replacements) framed with Tulip Poplar, (Liriodendron tulipifera) also a lightweight species favored by the bridgewrighting community where available. Replicated rafters, like their predecessors, are tapered over their length, one inch wider at their tail than at the ridge. This likely not an ascetic choice, but done as part of an overall strategy to minimize dead load. The original floor beams were replaced sometime in the 1920s, the bridges final decade of service, with mixed species Ash and Oak. This as an attempt to increase load carrying capacity. The only original White Pine floorbeam to escape replacement, was the one found at centerline of truss which was tenoned through the king post at midspan. All others were bolted to the sides of their adjacent posts, and were easily replaced. This strategy seems to have failed, (the bridge was bypassed in the following decade) and the additional weight was part of the why the bridges framing became severely distorted in the decades of neglect to follow. These hardwood replacements had heavy infestations of Deathwatch and Powderpost Beetles (Bostrichoidea) and were again replaced with timbers of appropriate species in the recently completed restoration.

External links

• Gilpin's Falls Covered Bridge, Cecil County at Maryland Historical Trust
• http://cecilcounty.wordpress.com/2010/01/17/joseph-george-johnson-built-covered-bridge-that-stood-test-of-time/