What is a Timber Covered Bridge
A timber-covered bridge is a technical name for a specific kind of structure, not just any bridge with a roof. Covered bridges are defined by a timber truss (or frame) that distributes the weight of the load-bearing deck. The truss design determines how long a span it can have and how complex it is to build. This makes them different than simple timber beam bridges or other similar structures. Typically, covered bridges are structures with longitudinal timber trusses which form the bridge's backbone.
Of course, to be a timber-covered bridge, that truss must also be covered. With its roof, deck, and siding, most covered bridges create a nearly complete enclosure. The covering of the bridge is designed to actually protect the bridge from the weather and extend its lifespan.
Uncovered timber bridges typically have a lifespan of only 20 years because of the effects of rain and sun, as well as snow and ice in the colder regions. A timber-covered bridge, however, could last as long as a century before major restoration or replacement is necessary.
As the early settlers who arrived in North America began moving inland, there was a need for building bridges to cross the streams and rivers that blocked their trails. Originally, local entrepreneurs established ferry services charging to be ferried across, the more difficult crossings. Early timber-covered bridges in America were often owned by companies or private people, and they charged others to cross them. Today, most existing timber-covered bridges in America are owned by cities, counties, and townships and people can travel across them for free, though a few are still owned privately.
Wooden bridges were the norm, mainly for the low cost of building materials. Timber-covered bridges date back to a time in history when almost everything was made of wood because of its abundance. Working with wood, like any material, has its advantages and disadvantages. Timber is lighter than stone and cheaper than iron or steel, but still very strong. However, wood also deteriorates faster.
Protecting the wood truss and deck from the weather was the fundamental reason for covering a bridge, but there were other reasons as well. Adding siding and a roof reinforces the truss and strengthens the bridge, as well as allowing builders to build longer bridges. Not only that, it provides shelter for those caught out in a storm, as well as a place for local gatherings.
Popular myths abound explaining why bridge builders began putting covers over bridges. Some people believe that the sides prevented horses from shying at the sight of rippling water. Some believe that since barn builders often constructed covered bridges, they automatically added a roof by the force of habit. Some even have speculated that the timber cover was intended to prevent travelers from knowing what kind of town they were entering before it was too late to turn around.
Traditionally, timber-covered bridges were painted red, as red paint was cheap. Before paints became common and affordable, farmers still needed a way to protect their barns. To solve this problem, they mixed together three things they had plenty of - skimmed milk, lime, and rust (iron oxide). This mixture created a red, paint-like coating that protected the wood and helped keep the barn warmer in the winter. Therefore, covered bridges were typically painted red because it was less expensive.
Even in their sometimes dilapidated or poorly restored condition, many of the remaining covered bridges are still in use on public roads today, reaffirming that these venerable structures are more than just quaint leftovers of the past. They are an integral part of social, cultural, and engineering heritage that merits preservation.
While most covered bridges are not part of the national highway system because they do not meet modern safety standards for roads, plenty of cities and towns allow them to be used for vehicular traffic. A handful of places limit them to pedestrian traffic only, because of safety concerns. Even though most covered bridges are only one lane, there have been a handful of two-lane bridges. Regretfully, only five of them still exist. Most timber-covered bridges are designed for cars, wagons, or foot traffic; some of them are made for trains. These railroad bridges can accommodate the extra weight of a train because they are fortified with heavy timbers and double latticework on the siding.
Covered bridges have always been wrapped with romanticism. Back in the day, these majestic structures spanning small brooks and mountainous rivers were the perfect place to go courting. Consequently, they earned the alluring nickname of “kissing bridge.” The nickname spread across the nation. And it is easy to understand why, as most covered bridges are surrounded by a peacefulness tied closely to our past.
There used to be more covered bridges. The whole world is down to only about 1600 timber-covered bridges still standing on our planet. The high cost of maintenance, their limited utility, and a lack of concern about history have caused a vast majority of our bridges to disappear. Sadly, vandalism is another cause of their vanishing.
The good news is this romantic appeal of covered bridges is a modern phenomenon. In the past, these bridges were viewed as simply utilitarian. But, since people began moving away from farm life and rural areas, and into the bustling cities, the often pastorally located covered bridges began to remind us of a past we were beginning to forget.
Fans of covered bridges have formed societies and organizations dedicated to the preservation of these lovely bridges. With their help, many bridges are still strong and standing. It only takes driving across one and looking for a place to park to understand this romantic relationship between bridge and man.
There are numerous bridge festivals held across the country, as well, by fans of covered bridges, to bring awareness to the need to preserve them, and simply to celebrate them. The best-known bridge festivals in the United States are in Washington County, PA; Switzer, KY; Ashtabula County, Ohio; Parke County, IN; and Columbia-Montour County, PA.
The festival in Parke County, Indiana is the largest covered bridge festival in the nation, being conducted each October in a county that bills itself as the Covered Bridge Capital of the World. The county may be correct in that estimation. Parke County has thirty-two covered bridges, each of which is rich with history and stories about the people, industries, and weather that have affected them over the centuries. Most of Parke County’s covered bridges were built between 1856 and 1920.
For more information on timber-covered bridges visit:
- Theodore Burr Covered Bridge Society of Pa. - - - www.tbcbspa.com
- Dale J. Travis Covered Bridges - - - www.dalejtravis.com/bridge/cbridges.htm