For people traveling from the northeast quadrant of Arkansas to Oklahoma, US-64 through Vilonia is a popular cut-off to avoid going through Little Rock. However, one high school, a middle school and 2 elementary schools are all located right on US-64, a serious safety concern with the traffic volume. The average daily traffic volume of 7,000, including 16% trucks, easily exceeds the local population of just over 3,900. The Vilonia Bypass was designed to alleviate this issue and accelerate travel time. A previous project for the Arkansas State Highway & Transportation Department (AHTD) constructed the bridges.
Schedule & Complexity
Bid in March, 2010, the project was afforded with a 300 working day schedule. The biggest challenge to the project schedule was delivered in the form of a tornado. The April, 2011 tornado that went through Vilonia hit the jobsite and, among other things, turned over trailers, damaged equipment, uprooted trees, porta-jons and traffic control devices. A drunk driver apparently trying to flee the tornado ran into the ABG paver, causing severe damage. Heavy rains continued for several weeks thereafter.
Construction & Innovation
The bypass provided 10 miles of Portland Cement paved four lane highway with asphalt tie-ins at both ends. The major scope of work included 306,500 SY of 9" and 109,000 SY of 6" dowelled PCCP, 212,000 tons of Aggregate Base Course (Class 7), 115,000 Tons of Cement Stabilized Base, 6,900 Tons of asphalt bondbreaker, electrical and traffic signalization, drainage and erosion control, earthwork and pavement marking. Two concrete box culverts, a 5-barrel 10'x5'x55' and a 6-barrel 10'x6'x65', were also included in the project.
The contractor began the project by building haul roads into the project so all deliveries were able to bypass the town and not add to the congestion. This allowed access to the jobsite from both ends, eliminating potential conflicts with on-going construction activities. AHTD accepted a value engineering concept proposed by the concrete paving contractor to reconfigure the tie-ins at the existing highway. This replaced a large quantity of designed asphalt paving with PCCP, provided a better construction flow and accelerated the paving schedule.
Class 7 aggregate base course was placed at varying thickness, as needed and topped with 6" of cement stabilized crushed stone base. This was followed with a 1"asphalt bondbreaker and finished with 9" of dowelled PCCP. The mainline concrete was placed at 26' wide, using a Guntert & Zimmerman 850 slipform paver equipped with an automatic dowel bar inserter and tie bar inserter. The 6' median and 8' outside shoulders were paved using a Gomaco 6300 paver in tandem with an RTP 500 material spreader to place 6" of dowelled PCCP over class 7 aggregate base. A Rex, Model S Central Mix plant was used to batch the concrete, which was hauled to the paver in tandem dump trucks.
A project-specific Quality Control Plan was prepared and implemented by the project Quality Control Team. Per the project specifications, the concrete paving contractor hired a certified Quality Control Firm to perform separate, independent testing. AHTD performed companion QA testing. All results were shared continuously, allowing any necessary adjustments to be made. The attention to detail led to the project receiving 100% of the available incentive.