OR201-OR20 Interchange

An ODOT interchange improvement project converted a three-way stop sign intersection into a roundabout interchange. The designs called for both rigid and flexible pavement sections. The project encountered silty subgrade that was pumping due to saturated conditions. The contractor built a section with three layers of TX160 that used ballast stone in the base and aggregate base in the section above. The design was unable to pass Oregon’s stringent proof roll requirement of 0” of deflection for a pavement section, so a fourth layer of TX160 was placed in the upper aggregate base layer to complete one segment of paving.

Tensar engineers designed a new section using Tensar+ design software. The new design used advanced large aperture InterAx NXL geogrid to stabilize the 4” minus ballast rock material. The upper section was then stabilized with two layers of InterAxNX850 and aggregate base. The higher-performance InterAx products were able to better stabilize the section to pass proof roll. The rest of the paving sections were built with the new three-layer design, saving both time and cost all while outperforming four layers designed with an older generation geogrid.