Determination of Improved Pavement Smoothness When Using 3D Modeling and Automatic Machine Guidance

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FHWA Publication No.: FHWA-HRT-21-021
FHWA Contact: Matthew Corrigan, HRDI-20, (202) 493–3365, Matthew.Corrigan@dot.gov

INTRODUCTION

In recent years, the use of AMG technology in constructing pavement structures has increased with growing market-led adoption by construction contractors. Efficient construction is a key benefit of using this technology and has led to its rapid adoption in paving; this efficiency results in cost savings, safety improvement, consistent paving-layer thicknesses, and higher material yields. As SHAs deploy specifications, guidance, and manuals to manage and support the use of AMG technology and related construction-inspection automation for grade control, more questions are being asked about how else construction outcomes might benefit from this technology. Improved initial pavement smoothness has been touted as a potential positive construction outcome resulting from the use of AMG technology–equipped machineries (i.e., pavers and graders) because of their superior vertical-grade control and accuracy. However, proof of this benefit is not documented.

In the context of this study, AMG technology is defined as using positioning devices, specifically Global Navigation Satellite Systems (GNSS), laser-augmented GNSS, and/or robotic total stations, on construction equipment (e.g., scrapers and paving machines) for machine guidance and to establish machine control to grade either all layers of a pavement structure for concrete-pavement projects or to subgrade layers for asphalt-pavement projects. Non-AMG technology, then, is defined as using traditional construction equipment to control the grade of pavement layers (e.g., all layers of a pavement structure for concretepavement projects and subgrade layers for asphalt-pavement projects).

Initial pavement smoothness is an important aspect of a pavement structure's functional service life. As a proven paving adage goes, "If you build the pavement smoother, it will stay smooth longer." Capitalizing on the ong-term benefits of achieving better initial pavement smoothness has been a goal of both the concrete- and asphalt-paving industries for decades.