A Fresh Start at the End of World War II
Texas and the rest of the nation rejoiced when World War II ended in 1945. Victory energized the population as the war improved the economy. Life suddenly felt very different from the Great Depression in the 1930s. The road ahead was ripe with opportunity. The Texas Highway Department (THD) changed the state’s highway system in this post-war era more than any other time in its history.
A Real Roadblock
Construction stalled during the war due to serious shortages of concrete, steel, and manpower. As soldiers returned and the population of drivers increased, people were on the move. The Texas transportation system was a real roadblock. In 1945 Texas had more dirt roads than paved. These outdated roads meant that drivers risked unsafe bridge crossings or getting stuck in deep mud during the rainy season. Texas growth created a critical need for a new network of roads and bridges. It was a challenge as big as Texas.
THD Ensures Safe Crossing into a New Era
THD anticipated this transportation problem and planned for it during the War. Gone were the days of wartime shortages. With new funding from the federal government, plans for roads and bridges were put into motion.
In order to connect Texas’ many rural communities, the farm to market road (FM road) system became a THD priority. THD began building 36,000 miles of roads that connected farmers and ranchers with growing cities. The project helped rural communities become less isolated and bring their products to market.
With that many new roads THD had another challenge – building all of the river and stream crossings for the new or upgraded routes! Bridges that were safe and quick to build were badly needed, not just on FM roads but on new freeways and improved city streets as well.
From Postwar into the Future
Between 1945 and 1965 cooperative research teams at THD, the University of Texas at Austin, and Texas A&M University rose to the challenge. These collaborations produced many innovative ideas. Some were completely new, while some were based on work done elsewhere in the country and adapted to the needs of Texas. The teams also took advantage of technological advances like prestressed concrete, neoprene pads and high tensile bolts.
Combined with the know-how of the engineers, new technology allowed for the creation of brand new bridge designs. The bridges could be built inexpensively, safely, and quickly. In fact, two new types of bridges were invented right here in Texas: the pan-formed girder bridge and the FS slab bridge. Thousands of these types of bridges were built all over Texas.
THD engineering even allowed for clever adjustments to market pressures. For example, when the Korean War created another steel shortage, engineers focused on building prestressed concrete bridges. When steel was available again, engineers designed lighter and stronger steel bridges that used less steel and were cheaper.
TxDOT Continues THD’s Legacy
THD’s hard work paid off. By September 1965 Texas had over 15,000 new bridges – that’s a rate of 2 bridges a day for two decades! The pre-war sparse network of muddy roads that took years to upgrade were a thing of the past. THD’s bridge program supported growing communities, made valuable connections between rural and urban areas, and helped Texas become an economic powerhouse. Today, the Texas Department of Transportation (TxDOT) keeps going Beyond the Road as it continues to support connections that matter to Texans.
Post-1945 Bridge Highlights
To learn more about some of the most unique of these historic bridges from 1945–1965, see the Post-World War II Bridge Highlights.
Glossary of Terms
All-Welded Construction Bridge: A bridge on which all the connections are welded—no rivets or bolts are used. All-welded construction helped THD cut down on using expensive rivets between 1945 and 1965.
Beam/Girder Bridge: A type of bridge structure. Girders and beams are both long pieces of iron, steel, or concrete that are used to build the support structure of a bridge. Girders are bigger, longer, and deeper than beams.
Bearing Plate: A component of a bridge’s supporting structure. It is located between the deck of a bridge and its piers, or upright supports. The plate covers the ends of the piers and lets the different parts of the bridge move slightly against one another without causing damage.
Concrete: A building material made out of stone mixed with other components such as gravel. In Texas it is common to mix limestone, a local material, along with ash and gravel.
Concrete Box Girder: A bridge type that uses hollow concrete boxes as its main support. This type of bridge was not frequently used between 1945 and 1965 in Texas.
Concrete Pan-formed Girder: THD developed this bridge type after World War II. Concrete was poured directly into large steel molds called pans to make girders and beams (instead of using steel or iron). The concrete was poured on-site (cast-in-place). Pans were reusable, and concrete is inexpensive. Many farm to market road bridges between 1945 and 1965 are concrete pan-formed girders.
Farm to Market (FM) and Ranch to Market (RM) Road: Roads in rural areas. Also known as a secondary road system. Texas is the only state in the Union with its particular system of farm to market roads.
FS Slab Bridge: A bridge type developed by THD after World War II. These reinforced concrete slab bridges have high curbs that are poured in one unit with the slab, which allows the curbs to act as small girders and help carry the load. Also known as concrete slab. Fun fact: despite being created in Texas, no one today knows for sure what “FS” stands for.
High Tensile Bolts: A cheaper and easier to install alternative to rivets. These bolts are made of carbon steel and are heat treated to increase their strength.
Interchange: A series of roads passing over others on bridges with ramps to connect them. They allow vehicles to move from one road to another without having to stop. Interchanges can be two-, three-, or four-levels high.
Prestressed Concrete: Concrete with taut steel wires, known as tendons, running through it to improve its compressive strength. Prestressed concrete uses a limited amount of steel but is incredibly strong, which means bridges can be longer and sustain more weight. Prestressed concrete can be created with either post-tensioning or pre-tensioning. Post-tensioned concrete requires stretching the steel and attaching it to an anchor on site. To create pre-tensioned concrete, the steel is stretched and held under stress until the concrete is poured. Pre-tensioned concrete was precast before arriving at the job site and was more commonly used in THD bridges.
Neoprene Pads: Also known as neoprene bearing plates. Constructed of high-grade synthetic rubber to support heavy loads on longer bridges. Developed by a THD engineer in 1958, they are used on bridges all over the world today because they are more durable and economical than steel bearings.
Rivets: A metal pin that holds together two plates of metal. Its headless end is beaten with a hammer to spread out to a size larger than the diameter of the hole to make a second head. By the early 1950s, welding and high tensile bolts began to replace rivets because these technologies were less time and labor intensive than riveting.
Span: A distance between two bridge supports.
Steel: An extremely hard building material. It is an alloy, or combination, of iron, carbon, and other elements.
Texas Department of Transportation: Known today as TxDOT, it was previously known as the Texas Highway Department. Founded in 1917, TxDOT is charged with the construction and maintenance of roads, rail, aviation, and public transport throughout Texas.
Welding: The process of joining pieces of metal. The surface of the metal is heated to an extremely high point and then hammered or pressed together.