A Covered Bridge is defined as a bridge in which the trusses, sides, and roofs are
made of wood, creating a complete enclosure; they were built that way to
protect the structural integrity of the bridge that, left exposed, would
otherwise have a useful life of only 10-15 years.
These Structures were built throughout the world during 19th century. In
the United States, Philadelphia lays claim to the first bridge, built in the early
1800s, that spanned the Schuylkill River by 30th Street. Eventually,
nearly 12,000 covered bridges were in operation. By the 1950s, the hat number
shrank to less than 1,500 as more affordable and durable materials came into
existence.
Pennsylvania has 219 Covered Bridges the most of any State
Early
Timber covered bridges consisted of horizontal beams laid on top of
piles driven into the riverbed below. This construction method meant that the
length between bridge spans was limited by the maximum length of each beam;
development of the timber truss circumvented that limitation and allowed
bridges to span greater distances than those with beam-only structures of
stone, masonry or timber arch structures.
European
Truss Bridges used king and queen post configurations. Some early
German bridges included diagonal panel bracing in trusses with parallel top and
bottom chords. Wood deterioration upon exposure to weather was addressed with various
forms of coverings. Beginning around 1820, new designs were developed, such as
burr, lattice and brown trusses. By mid-century, the introduction of wrought
iron and cast iron led to metal rather than timber trusses, except in areas
where large timber remained plentiful.
Ask us about our anchor locations from which you can
best base your travel movements, mindful that you are likely to visit three to
four places in a compressed period of time, typically 7 to 10 days, and
experience multiple interests that range from cultural to culinary, wellness
and the environment.
Smart
Trip Planning Logistics Locations Costs Time and Personalized Solutions
Connect with Tema
for
Covered Bridges Travel Itineraries
Local
Knowledge Global Reach
tema@arezza.net |skype arezza1