The Alabama Department of Transportation (ALDOT) faced a significant challenge in widening a section of Interstate 85 (I-85) while simultaneously adding a median barrier wall. This project aimed to address the growing traffic demands in the region and enhance safety by preventing crossover accidents. A critical aspect of this challenge was ensuring that traffic flow could be maintained during the construction process.
ALDOT undertook a strategic approach to address this challenge, which involved the installation of a variable height Contech Slotted Drain™ system within the center of the median barrier wall during construction. Slotted Drain was chosen to effectively capture sheet flow in the lower areas of the crossover in order to prevent hydroplaning. A key consideration was the need to withstand repeated impact from HS20 loading conditions, which led to the use of heavy-duty slotted drain components. To reinforce the durability of these slotted drains, shear studs were welded to the sides of the grates before encapsulation with 750 psi flowable fill concrete. Moreover, ALDOT took the initiative to optimize the slope of the pipe to enhance the hydraulics of the drainage system.
Contech Engineered Solutions, a well-established infrastructure solutions provider, played a pivotal role in this project. The decision to collaborate with Contech was based on their extensive experience and a proven track record of successful partnerships with ALDOT on similar projects. Contech’s expertise in providing high-quality drainage solutions made them a reliable choice for the I-85 widening project.
The construction process began with the contractor trenching and grading the ditch bottom in the median. Subsequently, they installed the Slotted Drain system, taking extra precautions to ensure it could withstand the heavy traffic loads and the impact from vehicles. The final step involved backfilling the area with 750 psi flowable fill concrete, ensuring the stability and longevity of the drainage infrastructure.
The successful installation of the Slotted Drain system had a significant impact on the safety and efficiency of this section of I-85. By capturing sheet flow and effectively managing storm water runoff, the project mitigated the risk of hydroplaning and enhanced the overall safety of the interstate. The decision to use the crossover construction method minimized traffic disruption on this busy section of the interstate, allowing for a smoother flow of vehicles throughout the construction process.
Through meticulous planning and the use of innovative drainage solutions, ALDOT has not only widened I-85 to address the growing traffic demands but also created a safer and more efficient roadway for commuters. This project's success has provided ALDOT with the capacity to add more lanes in the future, further accommodating the increasing traffic in the region. The collaboration with Contech has demonstrated the importance of strategic partnerships and the effective use of advanced drainage technologies in infrastructure development. ALDOT's commitment to enhancing the state's transportation system has resulted in a safer, more accessible, and future-ready I-85.