This document discusses best practices for flexible pavement widening projects. Widening projects are undertaken to improve safety by reducing edge failures, provide greater traffic separation, and enhance pavement performance by addressing issues like rutting and drainage problems at the edges. Construction challenges include narrow work areas, variable subgrade support, drainage issues, and limitations on equipment. Failures can occur due to differences in the old and new pavement structures, improper joint construction, insufficient compaction and settlement, moisture penetration issues, and drainage or slope stability problems. The document proposes a webinar to gather input from transportation agencies, contractors, and equipment manufacturers on successful and unsuccessful pavement widening projects to identify good practices and standards.

1. 0-6748: Best Practice for Flexible Pavement
Structure Widening Projects
Introduction

2. Project Purpose
• Objective: identify best practices for
improving pavement performance on projects
involving widening of narrow pavement
structures

3. Reasons for Widening
• Reasons:
– Improve safety
• Edge failures & vehicle control
• Greater traffic separation
– Enhance pavement performance
• Edges deteriorating from softening due
to poor drainage
• Reduce rutting due to tire loads at edges
Other Reasons?
• Narrow widening: adding 1 - 6 ft.
width to shoulder

4. Construction Challenges
• Narrow work areas
• Variable subgrade support
• Surface and subsurface drainage
• Potential need for acquisition of additional ROW
• Keeping time short per task to maintain traffic flow
• Narrow widening equipment not worth purchase
• Project choices can depend on funding source
– CAT1, CAT8, RMC, In House

5. Failures
• Difference between old and new structure
– Differences in thickness, material properties, and
compaction
– Can result in:
• Rutting in existing or new pav’t
• Uneven settlements
• Cracking
• Different load bearing capacities for both structures
(Varin & Saarenketo, 2012)

6. Failures
• Joint construction and location
– Should not be placed under/near wheel path
– Traffic loading can cause reflection cracking
(Varin & Saarenketo, 2012)

7. Failures
• Settlement
– Sufficient compaction of new structure
else, differential settlement could occur
(Varin & Saarenketo, 2012)

8. Failures
• Moisture penetration
– Should:
• Maintain lateral drainage within pavement structure
• Proper Selection of base materials key
• Good Construction Inspection
– Else, can cause:
• Moisture penetration - base, subgrade softening
• Swelling and heave of heavy clays
(Varin & Saarenketo, 2012)

9. Failures
• Drainage
– Maintain sufficient pavement surface drainage
– Can result in:
• decreased bearing capacity
• Edge deformation
• Ponding of water (accelerates deformation - safety)
(Varin & Saarenketo, 2012)

10. Failures
• Slope stability
– Should ensure stability of side
slopes (inner & outer)
– Problems if ROW space is limited
– If steep inner slope:
• Could result in poor compaction of
widened section
– cause shear failure & edge
deformation
– Structure widening a challenge

11. Workshop Webinar
• Webinar Purpose:
– Obtain expert opinions
– Experience in pavement widening projects
• TxDOT personnel & transportation agencies
• Industry representatives
• Contractors
• Construction equipment manufacturers

12. Workshop Webinar
• Contractors, construction equipment
manufacturers & suppliers, & construction
industry representatives
– Identify construction projects performed well/not well
– Good practices
– Guidelines, specifications, standards
– Equipment
• TxDOT Districts
– Discuss projects that performed well/not well
– Good practices
– Guidelines, specifications, standards