A two-mile stretch of Overland Park's Antioch Road, from 151st Street to 167th Street, was in dire need of improvement due to increased traffic demand spurred by residential growth and a new Blue Valley School District complex.
The progressive Kansas community made this $13.6 million project a top priority during the 2009 construction season, requiring a coordinated effort among all involved to deliver on the key objectives of improving traffic flow and safety in an increasingly busy corridor that serves a rapidly growing section of southern Overland Park.
Of primary concern was to provide safer access to a multi-school complex, which generates a traffic volume of 3,000 vehicles per day. Projected traffic through this corridor is expected to nearly triple from 9,000 to 26,000 vehicles a day over the next 20 years.
The project involved widening an existing two-lane roadway to a four-lane, median-divided thoroughfare. A wide median was constructed to accommodate a six-lane roadway in the future with minimal encroachment on adjacent properties.
The new road construction consisted of a 10-inch full-depth fractionated recycled asphalt pavement (FRAP) over a six-inch open-graded aggregate drainage base. The top eight inches of subgrade were fly ash modified to further enhance pavement life. A new traffic signal was installed at the 159th and Antioch intersection (just north of the school complex) to further improve capacity and safety.
The project team managed traffic control and construction phasing to minimize disruption to the traveling public during construction. Antioch Road serves as the only access to the three-school campus, so student access and safety was a major element of the phasing effort.
Adopting new mix designs
The project included considerable use of temporary pavements designed to carry relatively high traffic volumes during the various construction phases. The city and primary contractor, O'Donnell and Sons Construction, partnered on the design of the asphalt used for the temporary pavement to test various asphalt mix designs containing varying contents of recycled materials.
This testing was used for an engineering study that was independently reviewed by two respected materials engineering firms. The research led the city to adopt a new Superpave asphalt specification that allows the use of both fractionated recycled asphalt pavement (FRAP) and recycled asphalt pavement (RAP). A notable feature of the specification is that it allows high percentages of FRAP in the mix. The study demonstrated that with careful control and design, FRAP, and to a lesser degree RAP, pavements can actually outperform mixes with all virgin materials.
Because the research was completed and reviewed prior to the conclusion of permanent paving on the project, Antioch Road became the first high-volume thoroughfare in Overland Park to use the new specification with a Superpave surface mix that utilized 35% FRAP.
As a bonus, that negotiated change saved the city $62,000 on this project alone, more than paying for the research that led to the new environmentally-friendly specification.
The project earned both a national and local project of the year award from the National Asphalt Pavement Association, recognizing the quality work performed by O'Donnell and Sons on a project over 50,000 tons.
O'Donnell's 'going green' initiative
After the project was bid with all virgin material specified, O'Donnell and Sons requested the city consider incorporating recycled asphalt mixes into the project. This was new territory for the city, having never specified recycled mixes.
The city and contractor took advantage of the temporary pavements required during construction to test various recycled mix designs. Satisfied with how those test designs performed, the city approved the change to incorporate recycled content into the permanent mix designs used in constructing the new roadway.