Assessment of the Trimble MX7 for Use in Creation of Alignment Files for the Intelligent Compaction and Paver Mounted Thermal Profile Methods

The objective of the work was to validate the Trimble MX7 system for use in collecting infrastructure information for creation of in-place alignment files for use with intelligent compaction and paver mounted thermal profiling technologies and also to provide the capability to collect other asset information along the roadway. One project per district; where conventional survey methods were already used to capture the in-place center alignment; was selected for verification of the Trimble MX7. Additionally; a project with photo targets was also used for more accurate verification of the system with highly accurate known points on the roadway. From these verification runs; the average position error of the Trimble MX7 trajectory in the X; Y; and Z direction was found to be 2; 2 and 3 cm; respectively. Forward intersection and reference plane extractions methods were used to extract the centerline feature. It was found that the forward intersection method provided more accurate feature extractions. On average; the difference between the MX7 and photo targets using the forward intersection extraction method was 0.26 ft (3.1 inches); while the 95 percent confidence interval was between 0.2 ft (2.9 inches) and 0.3 ft (3.2 inches). Similar position error results were also found when comparing the MX7 positions to alignment files created using conventional survey methods. It was concluded that the MX7 has the needed horizontal accuracy to capture the in-place centerline for use in creation of alignment files for the IC and PMTP methods.