Every three years, those involved in the construction industries head to Las Vegas to attend ConExpo-Con/Agg and witness first hand the changes and innovations in road-construction equipment. Every succeeding show is larger and more elaborate, as the industry and its equipment are constantly progressing.
Traces of ConExpo date back to 1909, when the event, known as the “Road Show,” was held in Columbus, Ohio, and was considered to be a “hazardous experiment” in which its 40 exhibitors were able to display “amazing new devices” that could “do the work of 15 horse-drawn units,” according to historical records.
The early shows were held annually but became a biennial event starting in 1934. The 1938 show in Cleveland featured both indoor and outdoor space and was a huge success.
Show activity halted during World War II but returned in 1948 after an eight-year absence and three years of planning and preparation. The 1948 Road Show held at Soldier Field in Chicago was the largest and most diverse show to date, reflecting the post-war ambiance of growth and enthusiasm.
The post-war boom brought significant changes to the road construction equipment industry as it grew to meet demands. After the 1957 show, the event was held on a six-year basis to accommodate its large size and the elaborate planning that was necessary. In 1963, the show changed its name to the Construction Equipment Exposition, and in 1969, the name ConExpo was officially adopted. The 1975 show in Chicago was the first to be open to overseas companies and featured an international business center.
ConExpo 1987 and ’93 were staged in Las Vegas to accommodate the increasing exhibit space needed and the growing numbers of attendees. In 1996, ConExpo joined forces with the Con/Agg exposition and became known as the ConExpo-Con/Agg show and would be held every three years.
Just as the ConExpo show itself has evolved over the years, so has the equipment it has showcased. From horse-drawn rollers and steam-powered equipment to the standardization of diesel fuel, road-construction equipment has changed drastically over the past century.
Learning to crawl
In 1904, Benjamin Holt, founder of Holt Manufacturing Co.—Caterpillar Inc.’s largest predecessor—developed the first tract-type crawler tractor. The crawler tractor was originally developed for agricultural use and did not get involved in construction applications until the 1920s. When Holt developed his crawler tractor, “up to that time, large-scale agriculture required machines that were more powerful than just a simple team of horses to handle the implements in the field,” Tom Berry, archivist for the Historical Construction Equipment Association, told Roads & Bridges. “Steam tractors were developed and came into use for farming and agriculture. Some of these machines got to be quite sizeable to generate the power required to do some of the work.”
In the Sacramento San Joaquin River Delta region of Stockton, Calif., the rich agricultural land and soft soil created problems, such as tractors sinking into the earth. “These tractors of sufficient power needed to do the weight weighed so much that they began sinking into the soft, spongy soil,” said Berry. “They tried different ways of working around it. Some were equipped with just ludicrously oversized wheels for flotation.”
Some of these oversized wheels were up to 45 ft wide and 12 ft in diam. and eventually became impractical. Holt came up with the idea of mounting a tractor onto a continuous belt that traveled on the ground, providing power to the belt to give it its forward motion. “The advantage of the belt was that it spread the machine’s weight over a larger surface of the ground and gave it better flotation on that kind of ground conditions,” Berry said.
When the machine was introduced in 1905, a member of the press saw it being demonstrated and thought it reminded them of a caterpillar in motion; hence the name caterpillar tractor was applied to the machine.
In the 1920s, crawler tractors were introduced into the construction industry when people began experimenting with dozer blades and other such attachments for their tractors, which have been standard issue ever since.
Holt’s competitor, a man named C.L. Best, also developed a line of similar tractors around the same time. In 1925, Holt and Best combined their operations and formed the Caterpillar Tractor Co., the giant of the American construction equipment industry today.
A century of paving
As the first roads were being constructed in the late 1800s, the term “macadam” was used for asphalt pavement, and it was originally placed by hand. Starting in the early 1900s, it was laid by a spreader that traveled on steel forms laid along the edges of the pavement.
The big breakthrough for asphalt paving came in 1931, when Blaw-Knox introduced the self-propelled Ord Finisher. This paver had a “mechanism to allow different heights of the materials to be placed, which was a new design feature,” Scott Wiley, marketing manager for large pavers at Ingersoll Rand, told Roads & Bridges. “Before that, they would have to reset the forms to get the next lifts.”
In 1932, the Foote Co. of Nunda, N.Y., (purchased by Blaw-Knox in 1948) introduced the Adnun paver—the first self-propelled non-form riding finisher used for placing asphalt and stone and one of the first laydown machines to eliminate sideforms.
Blaw-Knox introduced the Paver Finisher PF-90 in 1954, the first pneumatic rubber-tired asphalt paver. With the development of the highway system in the 1950s, pavers evolved to keep up with the demands of the industries. The PF-90 demonstrated the separation of the material-handling portion of the paver from the propel system. This separation allowed for better control of the material and better pavement performance being laid behind the machine.
Another evolution of the PF-90 was the automation grade-slope systems in which, “you could take some variability out and lay material more precisely, for both grade and slope,” said Wiley. “So we had smoother and more consistent roads.”
In 1968, Blaw-Knox became the first company to offer a full-width paver on pneumatic tires. That same year, they also were the first to introduce 40-ft paving widths on pneumatic rubber tires.
Ingersoll Rand purchased Blaw-Knox from the Clark Equipment Co. in 1995, and is celebrating its 75th anniversary of creating road-building equipment this year.
Paving and creating concrete
While the earliest concrete pavers date back to the late 1800s, the first major innovation came in 1907 with the development of a new type of mixer in which the skip was over one end of the machine and the concrete was discharged out the other end.
“That was important because that way they could just pull the [mixer] along the road as pavement was being mixed and poured and it discharged the concrete behind it as it was moved,” said Berry. With the other types of mixers, “the flow of materials went across the machine’s direction of travel, so they had to constantly shovel back and forth and go through a lot of extra work.”
In 1918, concrete pavers were mounted on crawlers, similar to the crawler tractor, which gave it more mobility and the ability to move itself. Up until the 1960s, the concrete paving machines traveled on forms that looked like steel rails along the roadbed. During the 1960s, slipform pavers became standard technology in which the paver “moved along the roadbed and moved the forms along with it as it moved,” said Berry.
The 1960s also saw the introduction of central-mix batch plants, where concrete was mixed at the batch plant and then hauled by transit mixers or trucks to the paving site, and then the concrete was spread by the paving equipment. This method has pretty much been standard ever since.
GOMACO was founded in 1965, and is a leader in concrete paving technology today. The development of their cylinder finisher to meet the needs for finishing wider bridge decks of the highway system established GOMACO as a recognized name in the construction equipment industry and has since evolved into their current C-450 concrete finisher.
In 1969, the expanding GOMACO offered the C-450 on tracks and combined it with a slipform paver. GOMACO went on to revolutionize curb-and-gutter construction in 1970, with the development of the GT-6000 curb-and-gutter trimmer/slipform, which enabled simultaneous trimming and pouring, allowing contractors to achieve 200 ft of production in a half-hour’s time.
GOMACO expanded its paving line with the GP-2500 full-width slipform paver for interstate and mainline paving, and in 1984 they introduced the GP-5000, capable of slipforming mainline and airport pavements in widths up to 50 ft. GOMACO’s current product line includes equipment that will slipform and finish concrete slabs up to 150 ft wide.
Rolling through the years
As more and more roads were being built across America in the late 1800s, compaction equipment was developed to create these roads and their subsurfaces. Rollers have had a long history of use in the U.S. A steam-powered roller was used on New York City streets as early as 1869, and in 1878, Aveling & Porter manufactured the first “classic” steam roller.
“The earliest rollers were drawn by horses or oxen,” said Berry. “They were steam powered after that,” he added. These machines were often called steamrollers, even after steam was replaced by internal combustion in the 1920s.
Soil compaction technology was largely improved with the sheep’s foot roller, which was widely used in the early 1900s. This type of roller had a steel drum with metal pegs on it that would tamp the soil as it rolled along. The metal pegs were designed to compact the dirt just as a herd of horses or oxen would. “In fact,” said Berry, “these pegs were configured to look something like animal hooves.” These rollers were pulled by a team or tractor, and some are still used today.
Starting in the 1950s, rollers were set up to be self-propelled by mounting a diesel engine to the back of it. In the late 1950s, but taking off in the 1960s, vibratory compactors became commonplace. These had steel drums that were similar to the sheep’s foot rollers and three-wheeled tandem rollers, but inside the drum was a whirling eccentric that would impart a vibrating motion to the drum and the operator could then control both the speed of the vibration and the vibrating force. With this technology, operators “could get the best compaction results for working on asphalt or gravel or dirt,” said Berry. “That’s pretty much standard technology now.”
In many cases, the equipment’s original design concept is still used today. Such is the case with tandem rollers, which were developed in the early 1900s. These rollers used two full-width drums for compaction, and are still used today for compacting asphalt pavement.