Full-Lane Coverage Micromilling Pavement-Surface Quality Control Using Emerging 3D Line Laser Imaging Technology

Abstract

Facing pavement preservation challenges as a result of funding shortages, the Georgia Department of Transportation (GDOT) has developed an innovative micromilling resurfacing method to cost-effectively preserve its pavements. The cost saving is significant: approximately $60,000 per lane mile. To ensure that a smooth micromilled surface texture provides a good bond and water runoff capability, which is the key in this new method, a new, stringent ridge-to-valley-depth (RVD) specification has been established for quantitatively evaluating micromilled surface quality. This paper explores the possibility of using emerging three-dimensional (3D) line laser imaging technology to develop a full-lane quality control method that can measure RVD, provide quality control covering a full lane, and identify problem areas. A lab test was first conducted to critically assess the accuracy of the proposed method by using an artifact: a wood panel with V-shaped grooves of a known depth to simulate the ridges and valleys on a micromilled surface. Results show that the proposed method is very promising and can measure RVD with an error of less than 0.4 mm (0.016 in.). A field test was conducted by using Georgia Tech’s sensing vehicle to collect 3D range data at two 0.8-km (0.5-mi) segments on a micromilling resurfacing project on I-95. Results show that the RVDs in the transverse direction can effectively and quantitatively differentiate between smooth (mean RVD=2.9 mm; 0.114 in.) and rough (mean RVD=4.8 mm; 0.189 in.) micromilled surface textures. A case study shows that other problem areas on the micromilled surface, such as underlying cracks and isolated rough spots that will lead to premature failure, can also be identified by using the proposed method, so proper pretreatment methods (e.g., deep patches or crack sealing) can be effectively applied before resurfacing to ensure the longevity of the pavement. At the end of the paper, conclusions are made and recommendations are discussed for future research.