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SH 161 Overview Image in Grand Prairie, Texas

Finding Innovative Solutions When Traditional Subgrade Stabilization Methods Are Not Feasible

Project Background

SH 161 (IH 20 to South of Egyptian Way), Grand Prairie, Texas

State Highway (SH) 161, is an essential component of the President George Bush Turnpike (PGBT), a 52-mile toll road, forming a partial loop around Dallas, Texas running through the northern, northeastern and western suburbs.  SH 161 is a toll road from Irving to Grand Prairie, Texas. HVJ Associates® provided the pavement design, working as a subcontractor for Professional Service Industries, Inc. (PSI), for the main lanes and ramps for this new, 6.5-mile toll road from IH 20 to South of Egyptian Way for this North Texas Tollway Authority project.

Practice: Civil and Pavement Engineering

Sector: Road

Location: Grand Prairie, Texas

Services: Roadway Pavement and Subgrade Treatment Design

SH 161 Overview Map Image

The Problem

The project was located entirely on Eagle Ford Shale, which is known to be highly expansive material requiring treatment for a durable pavement.  Further, the formation is known to have high sulfates and chlorides which limited subgrade stabilization options.

The Goal

Manage the unsuitable subgrade soils cost-effectively with methods consistent with achieving the project schedule.

Our Solution

Traditional subgrade stabilization with cement or lime was not feasible due to the risk of pavement damage.  In subgrades with high sulfate and chloride concentrations, these materials react to form ettringite, which expands under the pavement after construction. This expansion can cause dangerous pavement undulations. A new North Texas Turnpike Authority design method was used to evaluate the swell potential of in-situ soils and design subgrade treatment. Options were to remove or replace or moisture treat to reduce the shrink-swell potential of the pavement subgrade and improve long term performance.

The depth of removal and replacement proved economically unfeasible. Subgrade treatment using moisture conditioning was a better option, providing suitable pavement support while eliminating the need to excavate, remove, and replace significant volumes of material. In addition to cost and time savings, this alternative significantly reduced traffic and environmental impacts of the project during construction.

 

The Results

SH161 (PBGT) was selected by Engineering News Record (ENR) as the Best Highway and Bridge project for 2013 in Texas and Louisiana.

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