The growing suburb of Overland Park, KS, located in the Kansas City metropolitan area, has historically been known as a top city in which to live. It has been recognized more than 10 times in the past 15 years for being an intelligent, safe and family-oriented city — including recently as one of National Geographic Adventure magazine's "50 Best Places to Live and Play." Part of achieving the city's good reputation, and keeping its nearly 168,000 residents pleased, is Overland Park's commitment to keeping its streets in good shape.
For years, Overland Park maintained its streets using chip seal because it is inexpensive and provides a durable surface. In the Overland Park area, chip seal costs approximately $1 per square yard, whereas micro surfacing costs approximately $2 per square yard — depending on which aggregate type you use. In comparison, a 2-inch mill and overlay together costs approximately $12 per square yard for residential streets.
Starting in 2006, the city switched from chip seal to micro surfacing. Although chip seal is a less expensive option, the city's residents felt the surface was too rough and the potential for free-flying rock could be harmful. The city already used micro surfacing on its thoroughfare roads and was familiar with the smooth, asphalt-like surface it provides for residents. The type of micro surfacing used (Type I, II or III) is based on the street classification.
Overland Park specified a "continuous run paver or approved equal" and a "hydraulically adjustable spreader box" in the project specifications for its 2007 micro surfacing programs. With streets that vary from 24 feet to 36 feet in width, it is important to have equipment that is maneuverable. Without this equipment, contractors are forced to make several passes in some areas, creating overlaps of the material and an uneven surface.
"Many contractors are hesitant to use a continuous run machine on residential streets because of its weight and the belief that it has less maneuverability than truck-mounted units," says Matt Laipple, EIT civil engineer and project manager for Overland Park's pavement maintenance programs. "Most of our residential streets are at least 6 inches thick, so we have not had any trouble with the weight of a continuous run machine, provided the street has a stable base. We also find that, with a good crew, the machine is very maneuverable and works around the city's obstacles without any problems."
Ballou Construction Co., based in Salina, KS, won the 2007 bid to micro surface streets in the north half of Overland Park. The company used a full-size Bergkamp M1 continuous paver and a variable-width spreader box to successfully micro surface nearly 1.2 million square yards of the city's residential, collector and thoroughfare streets north of Interstate 435. The job included approximately 240 residential and collector streets and seven thoroughfare roads — including two of the city's busiest thoroughfares: Quivira Road and 75th Street.
"Micro surfacing provides a quick in-and-out job that sets very fast," says Rex Eberly, Ballou's vice president and project manager of the Overland Park resurfacing project. "There is no loose aggregate, less dust, and the surface is nice and smooth. The latex modification of the emulsion is durable, lasting at least six to eight years. Overall, it is one of the best surfaces for the money."
The use of a continuous paver and a unique public relations program were key factors that allowed the project to go smoothly. Because of the job's complexity and potential impact to the citizens' daily travels, Overland Park required that the contractor implement an intensive public relations program. The city specified that the contractor maintain a clear line of communication with residents and that residents be alerted 48 hours prior to work being started.
Additionally, residents were provided with a map of their neighborhood, showing locations where the streets would be closed and where it was safe to park. Public relations requirements were provided within the project specifications, and the work was compensated by the inclusion of a bid item for the same.
Ballou Construction Co. has been in the micro surfacing business since 1980. It has approximately 90 to 100 pavement surfacing employees who have performed work in Kansas, Minnesota, Nebraska, New Mexico, Oklahoma, and Texas, and has built a good reputation with many cities in those states.
When completing the Overland Park project, Ballou focused only on micro surfacing and subcontracted the chip seal work. It placed approximately 431,000 square yards of Type III micro surface on thoroughfare roads and 752,000 square yards of Type II micro surface on residential and collector streets. This equates to what Overland Park considers to be 65 center lane miles — one center lane mile equals a street approximately 24 feet wide and 1 mile long.
A mixture of approximately 86-percent aggregate, 12-percent emulsion and 2-percent cement was used — with water added as needed, depending on the temperature outside. On hot days more water is required, but on cooler days it takes very little water to create a good mixture. In total, Ballou used 10,800 tons of aggregate, 318,000 gallons of emulsion and 211 tons of cement.
The continuous paver teamed with mobile support units to constantly lay the micro surface without stopping, thus eliminating starts and stops that create bumps for residents. The mobile support units carried aggregate, emulsion and water that were continuously transferred to Bergkamp's M1 continuous paver. The use of a variable-width spreader box allowed the crew to quickly adjust the width of the box to fit the varying shapes of the roads.
"The variable-width spreader box adjusts widths on the fly, which makes it easy to do tight jobs," says Eberly. "The combination of the box and the M1 continuous paver, which is very maneuverable, makes for a great team when resurfacing residential, collector or thoroughfare streets. Allan Jensen, the project superintendent, and his crew are very familiar with this equipment and the process, and were a major key to this job's success."
The contractor faced one main obstacle — the weather. Every day it rained, the crew was forced to stop working. In some stretches the job was stopped for multiple days in a row, requiring Ballou to rework its schedule and communicate the delay with the local residents. And, as with every job, the crew had to be extremely aware of its surroundings to avoid injury and damage.
"Micro surfacing is a safe and green process that doesn't create many environmental issues," says Eberly. "However, we are still very careful and take additional precautions when resurfacing near lakes, streams and other bodies of water."
Overland Park follows a specific procedure to determine which streets need maintenance. Each year, the city examines about half of its streets, so that every street in Overland Park is examined at minimum every two years. The city looks at the same spots in each pavement section, and tallies how many cracks, raveling spots, potholes, and other pavement defects exist. Based on the finds, city engineers calculate a Pavement Condition Index (PCI) to determine a deterioration curve and help decide when the pavement needs maintenance.
Many different things can affect each street's PCI, including the subsurface conditions, traffic volume, maintenance history, and sun exposure. In some cases, the city's residents don't see the need for preventative street maintenance because they can't physically see major damage on the street.
"Preventive maintenance should be handled before the street begins to develop significant problems," says the city's Laipple. "Once deterioration starts, it goes so fast that many times it is too late for maintenance when you notice the need. I like to compare it to your house's siding. When the siding on your house shows a little peeling paint, you don't tear it all off just because it needs paint. You protect the house from the elements by painting it before it deteriorates to the point that it is no longer serviceable. Streets are the same way. They don't need a new, expensive asphalt overlay if you preserve them before they get bad, which saves the city money and enables us to better keep all of our streets in very good condition."
On average, Overland Park performs maintenance on each street every seven years — at seven, 14 and 21 years old. Generally at about 28 years, streets are milled and overlaid with asphalt. The city plans its maintenance programs up to two years prior to the actual work being performed.
Upon completion of the project, Overland Park sent out a survey to each resident that was affected by the micro surfacing program. Both Ballou and Overland Park received very high marks from the residents. Overall, they were extremely happy with the construction workers' and city staff's attitudes and responsiveness, as well as the quality of the job. It seems certain that both the public relations program and the equipment used on the project were major contributors to this success.
"When done correctly, micro surfacing is very popular with our residents," says Laipple. "We plan to use the same public relations program in the future, and I can't complain about the final product. A Bergkamp representative stopped frequently just to make sure everything was running smoothly. The Bergkamp micro surfacing equipment was very maneuverable, and the final appearance looks much like an asphalt overlay."
Bergkamp manufactures all of the continuous paving units, mobile support units and spreader boxes that Ballou uses. Currently, it uses five M1 continuous pavers, 20 mobile support units and five variable-width spreader boxes on its resurfacing projects.
Editor's note: Eric Pulley is marketing coordinator for BMG, Fort Wayne, IN.