17e. 17th’S 25th ANNIVERSARY

Medallion Name17th’S 25th ANNIVERSARY

Significance – Denver owned and operated asphalt plants, so the city committed to paving their roads in high-maintenance asphalt concrete beginning 1912. In contrast, Colorado went with concrete road paving techniques. Finally, the convergence of state highways into Colorado convinced the city to go with more economical concrete streets in 1950.

Inscription – On December 10, 1975, 17th Street celebrated its 25th year as a concrete street. Anniversary invitations were engraved in Old English and former Governor John Love led the champagne toast.

In 1950, amid great City Council debate, 17th Street was the first concrete street in Downtown Denver. The initial cost of $188,000 was considered extravagant, yet it required no repairs for its first 25 years.

Location – 39°44’41.4″N 104°59’22.0″W

Details – There are always festivities on streets, but to celebrate a concrete street, well that’s an entirely different tale. If taken into consideration at all, streets are thought of as little more than road surface or pavement; a durable surface material laid down on an area intended to sustain vehicle traffic.

And why celebrate a concrete street? Concrete streets were late in coming to Denver. Truly, the first street in the United States to be paved with concrete was Court Avenue in Bellefontaine, Ohio, in 1893. The first mile of concrete pavement in the United States was on Woodward Avenue in Detroit, Michigan in 1909. Following these pioneering uses, the Lincoln Highway Association was established in 1913 to oversee the creation of one of the United States’ earliest east-west concrete-paved roadbed transcontinental highways for the new automobile.

The automobile era had driven into Denver, and the city needed to decide how best to improve and pave its urban grid. Experimenting with four separate materials, the city surfaced four blocks of Speer Boulevard in 1910. On successive streets, city crews alternated between asphalt concrete, tar concrete, a patented type of bituminous concrete known as “Amiesite” and tar concrete placed over an existing Macadam-style crushed and compacted stone base. Denver owned and operated asphalt plants, so the city committed to asphalt concrete when it paved eight additional blocks of Speer in 1912. From 1916 to 1918, the city paved thirty-five to forty blocks with asphalt and asphalt concrete.

Utilizing City assets is a prudent fiscal idea, as there are pros and cons for both concrete and asphalt roads:

  1. Concrete roads are more durable than asphalt roads.
  1. Frequent repairs are not needed for concrete roads when compared to asphalt roads. Extreme weather conditions are liable to damage asphalt roads more than concrete roads.
  1. Maintenance is easier with asphalt roads. Maintenance of a part of the asphalt road is possible.
  1. Concrete roads are not damaged from oil leaks, like asphalt roads.
  1. It takes less time to lay an asphalt road than a concrete road.
  1. Asphalt roads have better skid resistance and provide good traction. Snow melts faster on asphalt roads than on concrete roads.

Concrete is kind of a miracle material that hardens over time. The earliest large-scale users of concrete technology dates back to the Roman Empire. The Colosseum in Rome was built largely of concrete, and the concrete dome of the Pantheon is still the world’s largest unreinforced concrete dome. After the Roman Empire collapsed, use of concrete became rare until the technology was redeveloped in the mid-18th century.

While Denver was opting for asphalt, Colorado, as well as the rest of the country was going for concrete. The state learned after the 1918 problematic paving of the first Federal-Aid concrete road in the state went from Denver to Littleton. Beginning in the 1920s, federal aid paid for practically every concrete road in Colorado. These roads measured 18 feet wide, 6 inches thick at the sides and 7.5 inches thick at the center. Because of Bureau of Public Roads regulations, all pavements in Colorado had traverse joints every 30 feet and were laid on a two-inch sand cushion wherever the soil had a large percentage of clay. Most of Colorado’s soil is sandy loam. Colorado also used a 4-foot wide and 6-inch deep sand or gravel shoulder on the sides of the road. A 1923 BPR review noted “the pavements in Colorado are today in good shape. The only defects are minor in character, due to poor construction such as slight unevenness or roughness at the joints, or irregularities in the slab itself.”

As the 1920s progressed, the state built more concrete roads. An abundance of raw materials and available labor convinced engineers to use the durable concrete at every opportunity. A 1923 Highway Department audit found that the cost of concrete paving in Colorado averaged $2.22 per square yard, lower than in thirty-five other states.

The heyday of concrete-highway construction in Colorado lasted from the late 1910s to the 1930s.

During this period, builders used three standard mixes for construction: Class A and Class B concrete

and a paving mix for concrete roads. The paving mix consisted of one part cement, two parts fine aggregate (sand), and three parts coarse aggregate (gravel or crushed rock) mixed with enough clean water to form a stiff, workable substance. The Colorado Department of Highways used different mixes of concrete to form bridges, culverts, headwalls and spillways.

Concrete roads were converging on Denver. In 1948 work commenced on Denver’s Valley Highway, which we now know as the section of I-25 that through the Denver metro area. Once that was underway, grading work and ballast began for the 10.7-mile of the Denver-Boulder Turnpike. Asphalt was deemed a cost-inefficient and obsolete method of road construction. After consternation and arm twisted, Denver succumbed to paving their streets with concrete.

The city is in good company. Today, concrete is the most widely used human-made material. It can be formed into massive structures like the Hoover Dam and the Panama Canal, which are both made with reinforced concrete.

Quiz Questions

What is concrete?

What are some differences between concrete and asphalt?

Why did the United States need to pave roads?

Why did Denver initially decide to pave the city with asphalt concrete?

How do available funds and resources influence state and government decisions?