Ocala Highway Expansion Overcomes Subgrade Challenges with Geosynthetic Solution
Key Highlights
- A multi-tiered geosynthetic system provided a cost-effective and efficient solution to stabilizing and reinforcing a roadway over loose soils.
- MIRAFI RSi-Series features soil reinforcement, confinement, separation and filtration in one single product.
- Cost-effective roadway design over soft subgrades and poor soils is a common engineering challenge.
OVERVIEW
The City of Ocala has seen significant growth in the past decade, spurring increased traffic congestion. To alleviate these challenges, the city planned a road extension along the northwest side of Ocala that would include a new four-lane, divided highway. This portion of the project was built on a new embankment constructed through a gravel pit of an active mine.
CHALLENGE
During construction, careful planning and coordination were required to minimize disruptions to the mining operations. This involved close collaboration with the mining company to schedule work around peak mining activities while ensuring the safety of both construction workers and mine employees.
The newly planned route traverses a section of land that consists of deep fill placed over a large pit used during mining operations. Construction began in the summer of 2024, during a period of heavy rainfall that saturated the subgrade and created weak, rut-prone soils. These soft areas posed significant challenges, especially where the planned route crossed deep fill over the former mining pit. Voids, loose soils, and long-term settlement could adversely affect the performance of the roadway as well as its lifespan.
SOLUTION
To address concerns about voids, loose soils, and long-term settlement, engineers implemented a multi-layer geosynthetic stabilization system using 25,000 yd² (20,903 m²) of MIRAFI® RSi-Series. These high-performance woven geotextiles are engineered to integrate the five key performance properties essential for for roadway reinforcement and stabilization performance: high modulus, separation, confinement, high water flow and product identification. Its unique weave pattern allows RSi to combine high reinforcement strength with high water flow for improved performance.
Cost-effective design of a road or working platform over soft subgrades and poor load-bearing soils is a common engineering challenge. Utilizing a high-performance woven geotextile like MIRAFI RSi-Series that features soil reinforcement, confinement, separation and filtration with one single product, provides a significant cost savings compared with other materials. For example, when a geogrid is used in this application, a nonwoven geotextile separator is required. The use of only one product reduces the laydown area, installation time, and installation cost by half.
Instead of removing 2 ft to 4 ft (0.6 m to 1.2 m) of existing material as required in conventional construction, the MIRAFI RSi design provided a faster, more efficient solution. A two-layer system was implemented. MIRAFI RS580i was used to provide initial stabilization and MIRAFI RS380i was then used to reinforce the roadway base. This approach quickly created a firm, compacted platform, offering both reinforcement and separation to ensure long-term roadway performance while saving time and materials.
The new highway will significantly enhance the region’s transportation network, supporting economic growth and improving the quality of life for the community. The highway features modern infrastructure, including advanced drainage systems, sound barriers, and pedestrian walkways to ensure safety and convenience for all users. Additionally, the design incorporates environmentally friendly practices, such as the use of recycled materials and the preservation of surrounding natural habitats.