Bridge Lifting Operation in Buffalo, New York

Problem

In Buffalo, NY, New York State Thruway Authority (NYSTA) contacted URETEK and reported that two approach slabs at the North and South sides of the Youngs Road Bridge above the thruway had settled up to 3” across the span of the roadway. NYSTA also noted that a local contractor without roadway experience had previously tried unsuccessfully to bring the slabs back to grade and, while doing so, partially damaged the slabs.

Analysis

A visit to the site determined that this bridge’s sleeper slab design provided an unusually small footprint for the transition from the approach to the roadway. Due to the smaller footprint and the previous damage, this job had gotten a lot more complicated from an operations standpoint. URETEK’s on-site supervisor and his operations team’s experience was vital in preventing any further damage while bringing the sleeper and approach slabs back to grade as much as the structure would allow.

Solution

For the bridge stabilization effort, URETEK used the URETEK Deep Injection® (UDI) process and the patented URETEK 486 STAR® polymer to stabilize the soils under the roadway. Dynamic Cone Penetrometer (DCP) testing assessed preinjection soil conditions in each work area and confirmed the operations team’s injection plan. Crews then drilled injection holes on 4’ centers and installed injection tubes at three elevations. The team injected the highly expansive, high strength, lightweight, water-resistant URETEK 486 STAR polymer through the tubes and into the soils beneath the base to fill the voids & stabilize them. Injection continued until 1mm of movement was detected at the roadway’s surface, confirming adequate soil stabilization. Eventually, proper lift was achieved.

Result

NYSTA was delighted with the result of URETEK’s work. The operations team brought the bridge back to within a ½” of the original grade. The approaches were also lifted at the transition areas so that snowplow drivers could better operate the vehicle without fear of damaging the blades of the plows. For traffic in Buffalo, URETEK provided a repair solution that restored motorists’ smooth ride, and the life span of the bridge was increased at a fraction of cost and labor.

URETEK Deep Injection® (UDI)

Widely referenced throughout our industry, UDI involves the injection of structural polymer into base and subgrade soils to increase the load bearing capacity. This is achieved by injecting the polymer through small holes drilled directly through the pavement structure to depths determined by site-specific analysis. Our URETEK 486 Star® material flows easily into voids and weak zones within the soil mass below. Through a controlled chemical reaction, the expanding polymer compacts surrounding soils and applies a controlled pressure on targeted areas of the affected pavement above. If needed, a multi-injection design plan is utilized to gently return the pavement to its original grade. The composite material quickly cures into a strong, dimensionally stable, and water-resistant geo-material, providing years of reliable service.

URETEK 486 Star®

URETEK 486 Star® polymer is a two-component, high-density, expanding thermoset polyurethane system. It was developed to be the ideal solution for under-sealing, void filling, lifting of settled pavement, stabilization and stiffening of weak soils, and for encapsulating and sealing buried infrastructure. URETEK 486 Star® is environmentally inert, non-toxic, and resists underground water erosion or weakening due to its industry-leading hydrophobic properties.