Use of Automated Machine Guidance within the Transportation Industry (2018) / Chapter Skim
Currently Skimming:
Pages 95-108
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 95... ...
NCHRP Project 10-77 95 CHAPTER 9: ACCURACY OF AMG PROCESSES During various stages of the project life cycle, accuracy is a key issue, particularly surrounding the following areas of the project: • Initial data collection for developing existing surface terrain • Development of DTM and EED • AMG processes, procedures, and end-user competencies • QA/QC reported practices • Heavy and fine grading equipment operations • Paving equipment operations The survey conducted as part of this research specifically targeted these areas to gather input from contractors, software/hardware vendors, and agencies (See Chapter 3)
|
From page 96... ...
NCHRP Project 10-77 96 Frequency of the errors (by Error # shown in Table 9-1) and strategies for error detection and mitigation are detailed in Table 9-2.
|
From page 97... ...
NCHRP Project 10-77 97 Table 9-2. Frequency of Errors and Suggested Detection/Mitigation Strategies Error # Frequency Detection Mitigation Strategy Daily Seldom Project Duration Random 1 √ F Field QC Training and standardized protocols 2 √ Design phase Use of advanced surveying techniques, such as digital photogrammetry or LIDAR *
|
From page 98... ...
NCHRP Project 10-77 98 A frequent problem reported with GPS-based technologies is limited availability of satellites (and, consequently, poor signal attenuation) when operating close to structures, trees, or underground environments.
|
From page 99... ...
NCHRP Project 10-77 99 Table 9-3. Summary of Different Position Measurement Technologies System Accuracy Range User Cost Reference Conventional GPS (no corrections)
|
From page 100... ...
NCHRP Project 10-77 100 Table 9-4. Comparison of different types of construction machines (after Retscher 2002)
|
From page 101... ...
NCHRP Project 10-77 101 Pr ob ab ili ty D en sit y Pavement Layer Thickness Desired Target Deviation of mean from target Non-Uniform Support Conditions Uniform support conditions Figure 9-1. Conceptual Illustration of Comparison between Pavement Layer Thickness with Uniform Support Conditions and Non-Uniform Support Conditions Using AMG AMG Control for Single Phase versus Multiple Phases of Project Evaluations of accuracy are primarily based on assessment of one phase of the project or one machine.
|
From page 102... ...
NCHRP Project 10-77 102 where m repeated measurements obtained at a given location for I number of times by J number of operators or material types or support conditions or travel direction, using estimates from two-way analysis of variance (ANOVA) results (see Table 9-5)
|
From page 103... ...
NCHRP Project 10-77 103 on Project 3 cannot. While change in travel can increase the reproducibility error, having RTK-GPS can help significantly minimize the error.
|
From page 104... ...
NCHRP Project 10-77 104 Figure 9-4. CS74 smooth drum roller setup with SBAS-GPS on Project 3 with sloping gravel road Assessment Plan The research team developed an evaluation matrix of the several factors discussed above (machine related, technology related, and human related)
|
From page 105... ...
NCHRP Project 10-77 105 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 E le va tio n (m ) 257 258 259 260 261 262 263 264 Pass 1 - Downslope Pass 9 - Downslope Pass 2 - Upslope Pass 10 - Upslope Measurement Error based on one direction = < 1 cm Measurement Error based on both directions = 2.4 cm Project 1: CS74 with padfoot shell kit and RTK-GPS 0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 E le va tio n (m )
|
From page 106... ...
NCHRP Project 10-77 106 Table 9-6. Summary of repeatability analysis results on GPS elevation measurements on three earthwork project sites with and without RTK-GPS mounted on roller compactors Project Direction Elevation Range (m)
|
From page 107... ...
NCHRP Project 10-77 107 Table 9-8. Example Qualitative Assessment matrix of Accuracy Factors for Various Application Categories C at eg or y Machine Type Machine Related Errors Technology Related Errors Human Error M at er ia l T yp e Su pp or t C on di ti on s Sp ee d of O pe ra ti on T er ra in Sl ip L ow A cc ur ac y G P S (n o co rr .)
|
From page 108... ...
NCHRP Project 10-77 108 • Sources of errors contributing to the overall AMG accuracy were identified as an outcome from the AMG Phase I Workshop and were related to frequency of error, means for detection, and mitigation strategies to overcome the error. Survey outcomes from contractors, vendors, and agency personnel on factors contributing to the overall accuracy of AMG are crossreferenced to the findings from the workshop results.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.