TxDOT Research Library - TxDOT Research Project

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Best Practice for Flexible Pavement Structure Widening Projects

Project Summary

TxDOT has experienced problems with construction quality and performance on narrow widening projects (i.e., adding a 2- to 5- ft shoulder). The State of Texas has approximately 40,000 lane-miles of FM roads with 9- to 10ft wide lanes. [MapZapper 2011] In addition, approximately 20%, 26% and 36% respectively of roadways with 9', 10' or 11' lanes have either no shoulder or a 1' shoulder. [Machemehl 2006] These roads are potential candidates for lane or shoulder widening to improve safety performance and increase capacity. However, due to constraints regarding construction equipment limitations, material selection options and compatibility, construction methods and other issues, there can be problems with narrow widening projects. These challenges include inadequate compaction at the base layer joint interface, drainage within the pavement and at the pavement surface, either high, or, depressed surface layer construction joints and potential safety concerns. To effectively overcome these challenges, TxDOT has initiated this project to prepare a compendium of best practices and lessons learned regarding narrow widening projects. The primary goal of this project is to identify best practices for improving pavement performance on projects involving widening of narrow pavement structures. The objectives of this project are to: 1. review and document literature and current practices used by TxDOT districts, transportation agencies in other states and abroad, contractors and equipment developers; 2. seek to understand the mechanisms and actions that result in either poor or good pavement widening construction quality and pavement performance based on the literature, case studies, an expert panel Workshop and interviews; 3. develop a compendium of widening best practices, lessons learned and associated specifications / Design Standards that demonstrate the greatest potential; 4. conduct a training Workshop with case studies to assist districts in making the most effective design decisions, develop appropriate design details, and manage and inspect the construction of widening projects; and 5. prepare a comprehensive report that documents the information obtained during this study.

Project Number

0-6748

Status

Completed

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