TOMORROW'S ROADS TODAY - Maryland State Highway ...
TOMORROW'S ROADS TODAY - Maryland State Highway ...
TOMORROW'S ROADS TODAY - Maryland State Highway ...
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59<br />
or Bethlehem Steel types would be acceptable. The metal beams and girders also could be<br />
ordered by length and weight depending on the bridge design requirements (length and width of<br />
bridge, traffic volumes, crossing type). Unlike the bridges from the 1930s, the new bridge<br />
parapets were higher and closed so that drivers would be less distracted by looking through the<br />
parapets at the scenery beyond the bridge.<br />
However, since 1965, many of these bridges have also been altered by widening or<br />
redecking with new parapets. In the 1980s, many bridges had the parapet endposts replaced with<br />
trapezoidal shapes to increase driver safety at the approaches to the bridges. Another change was<br />
to add safety fencing across the bridges. The SRC made all of these changes in response to<br />
growing traffic and concern for driver safety on the associated highways. These types of<br />
alterations preclude these bridges from being able to convey their significance as mid-twentieth<br />
century bridges.<br />
By the 1950s, standardization was not a new innovation and did not result in a markedly<br />
different bridge design from those bridges built in the 1930s. The SRC began to use Standard<br />
Plans for its bridge designs in 1912 with plans for concrete slab and metal girder bridges. By the<br />
1930s and early 1940s, the SRC did not rely on the earlier Standard Plans, but began using<br />
standardized bridge elements to design and construct rolled and plate girder bridges for crossings<br />
that did not require a specialized solution. One change from the 1930s was that the bridges were<br />
no longer encased in concrete. Instead, the metal beams would be exposed but painted. Not<br />
using additional concrete enabled the SRC to further reduced the cost of bridge construction. In<br />
the case of concrete bridges, the SRC continued using reinforced concrete to design and<br />
construct slab, beams, girders and rigid frame bridges for crossings that did not require a<br />
specialized solution. These bridges were less expensive to construct because they were not the<br />
decorative arched bridges that were frequently built during the early part of the twentieth<br />
century. Prestressed concrete bridges were first built during the 1948-1965 period, but not<br />
universally incorporated into all concrete bridges on the state system.<br />
Bridge building was one of the most expensive undertakings for the transportation<br />
agency, and standardizing as much of the process helped to control the costs and construction<br />
time. Through the post-war period, SRC continued its earlier practices from the 1930s and 1940,<br />
building plate and rolled girders and reinforced concrete bridges that enabled the agency to<br />
produce similar designs for many new crossings. The large number of similar bridges<br />
demonstrates how the SRC made practical use of standardization to build the new highway<br />
system.<br />
The mid-century bridges were not constructed as the single most important element of the<br />
highway system, nor were they unusual designs. Rather, the bridges were constructed as an<br />
integral part of the associated highway, and there were many bridges on each highway that<br />
crossed other roads, railroads, and bodies of water along the route. Although the SRC<br />
constructed many bridges and highways during this period, that is not an exceptional event.<br />
During this same period, other state Departments of Transportation such as Delaware, New<br />
Jersey, Virginia, Nebraska, Tennessee, Oregon and California were constructing similar bridges<br />
and highways in order to keep up with growing traffic on state highways. The steel beam and<br />
girder bridges and reinforced concrete bridges constructed during this period by the SRC became<br />
a common resource found on every highway in the state and in many other states as well.