Bridges have historically provided necessary links in the transportation network, allowing people to get together, making possible the movement of raw materials and finished goods. Three Connecticut bridges recently listed on the National Register of Historic Places illustrate changes in bridge building in the late 19th and early 20th centuries.
Two employ the age-old technique of assembling cut stone into arches. Such bridges were costly, requiring extensive labor to quarry, shape and assemble the stones. But in some cases the durability of stone was worth its cost.
The oldest of the three bridges is the Burton Brook bridge, in Lakeville (in the town of Salisbury), built in 1873. The bridge serves Main Street (U. S. 44), once the Albany Turnpike, the principal east-west route across the northern part of the state. Heavy traffic levels dictated not only construction of local marble, but also the bridge’s generous 29-foot width—far wider than was typical for the time. This has also allowed the bridge to continue to serve modern traffic.
Also of stone is the Perry Avenue bridge in Silvermine, a part of Norwalk, built in 1899. At the time, Silvermine was a small village with a few small industries. The bridge crosses the Silvermine River just downstream from a mill dam, and the possibility of flooding seems to have justified stone construction. In the 20th century the community attracted a group of artists, many of whom drew or painted the bridge.
An alternative to stone construction was steel. Lighter and more flexible than stone, stronger than timber, and able to be mass-produced more cheaply in factories, steel bridges proliferated in the 19th and earlier 20th centuries. The wide variety of early steel bridge types gradually settled down to a few standard types. One was the “Parker modified through truss,” as seen in the Depot Street bridge in Beacon Falls. Patented in 1870 by Charles H. Parker, this design modified an early truss design by arching the top chord. The arch shape was more expensive to fabricate, but used less steel and—most important at a time when vehicles were becoming heavier and heavier—it was stronger.
The Depot Street bridge replaced an earlier structure that was becoming inadequate. Located in an industrial town, the bridge was crucial to shipping raw materials in to the factories and finished goods out, as well as to allowing employees to get to work.
The different structural systems determined the bridges’ appearance. Obviously, stone arches are heavy and solid looking, as the Burton Brook bridge demonstrates. But imaginative builders weren’t always restricted. The Perry Avenue bridge, with its shallow arch and low parapet walls topped by railings, manages to look much lighter and more graceful. Steel truss bridges are characterized by the ever-shifting interplay of structural members as one travels across them. They also provide a sense of enclosure, while still allowing views of the water and surrounding countryside.
How bridges were paid for also changed over time. In the latter part of the 19th century, most Connecticut bridges were still paid for by the towns, and town politics consequently played a role in determining what kinds of bridges were built and where. In Salisbury, the town selectmen voted in 1874, just a year after the Burton Brook bridge was completed, that from then on all town bridges were to be constructed of timber, not stone.
There were, however, other sources of funding. When an earlier Depot Street bridge was washed out in 1855, the American Hard Rubber Company, needing a replacement as quickly as possible, undertook to build it—closer to the factory.
In the 20th century, funding was more likely to come from the state, or even the federal, government. The new Depot Street bridge was constructed by the Connecticut Highway Department, and the town contributed only about one-fifth of the cost. The rest came from the state and from a federal Works Progress Administration grant.