Bridges: A Brief Historical Overview Essay

Modern bridges are built using a combination of iron, cables and concrete and range from smallscale bridges to mega structures that span large lakes, seas and mountains. The French and Swiss engineers are responsible for the development of reinforced concrete arch bridges at the end of the nineteenth century. In the United States, the Viennese engineer Joseph Melan developed the system of reinforcing arch bridges with trusses that was used to build the first bridge of its kind in 1889. The Pennsylvania General Assembly hired Theodore Burr to construct the first ColumbiaWrightsville Bridge between 1812 and 1814 that was 1730 m long and 9 m wide (Jackson, 23). The bridge had twin carriages, 54 piers and a wooden roof with openings at the sides for viewing the surroundings covered it (Klein & Hoogenboom, 205). The material used to construct the first bridge was stone and oak timber. The bridge accommodated traffic across the Susquehanna River for about 14 years before it failed due to severe weather.

Figure 1 The first Covered YorkLancaster Interstate Bridge

John Evans and James Moore constructed a second bridge between 1832 and 1834 that was 1710 m in length and 8.5 m in width. Like the first bridge, it was constructed using stone and oak timber (Caswell & William). The bridge had 27 piers, 2 towpaths, a walkway and a carriageway. During the Civil War, Union militia started a fire on the bridge with the intention of defending it against the Confederates but instead they destroyed the entire bridge. The bridge was the only way across the Susquehanna River for 25 miles on both the north and south and thus presented an opportunity for the Confederates under General John B Gordons command to prevent the advance of the Southern troops into Wrightsville. The confederates rigged the bridge with explosives to prevent the Southerners from capturing it. The explosives failed to detonate and the Union troops set fire to the bridge ruining it.

Figure 2 Third ColumbiaWrightsville Bridge destroyed by a hurricane

The Pennsylvania Railroad started the construction of the third wooden Howe truss covered bridge in 1869 and finished in the same year. Unlike the bridges before it, the materials used included steel, stone and wood. The bridge failed in 1896 after a catastrophic hurricane. A fourth bridge, the Pennsylvania Railroad Iron Bridge was constructed between April 1897 and May 1897 and it was considered the worlds fastest bridge built at the time. The bridge made of steel trusses consisted of 61m long prefabricated sections. A unique feature of the bridge was its resistance to fire, and severe weather that had destroyed the bridges before. The Iron Bridge remained in operation until 1958 and it was later dismantled to collect scrap.

Figure 3 Railroad Bridge

However, the vehicular traffic shared the bridge with trains and on completion of the Lincoln Highway in 1925 this led to a large traffic snarl up by the bridge, as vehicles had to wait for trains to cross the bridge first.