Validation of photogrammetric monitoring for trenchless construction applications

A primary concern of owners specifying trenchless installation and rehabilitation methods are surface movements during construction. Surface heave or settlement can occur as a result of contractor methodology, design, or geotechnical conditions. Performing quality assurance during and after construction provides owners with an understanding of what surface movements have occurred and if remedial action may be required. Traditional methods utilized to measure ground surface movements include surveying triangulation, geometric leveling, and global positioning system (GPS) surveying. This paper presents a procedure to utilize photogrammetry in the measuring of ground movements and examines its precision and accuracy in simulated field conditions. Utilizing consumer-grade digital single lens reflex (SLR) cameras, photogrammetry does not require highly trained personnel, takes less time, and costs less money than traditional methods. Accuracy is determined by comparing measurements taken with photogrammetry to those taken with traditional rod and level. The results are compiled and analyzed to determine the accuracy and precision of photogrammetry in measuring ground movements.