TERRAIN DATA FOR EARTHWORK QUANTITIES

AN EXPERIMENTAL STUDY WAS CONDUCTED TO DETERMINE THE RELATIVE ACCURACY AND COSTS OF VARIOUS METHODS OF OBTAINING EARTHWORK QUANTITIES. FIELD SURVEYS AND PHOTOGRAMMETRIC SURVEYS WERE MADE OF THE TEST SITE. FIVE STATISTICAL MEASURES OF ACCURACY ARE SHOWN FOR EACH OF THE SURVEYS. OF THESE, THE ARITHMETIC MEAN HAS BY FAR THE GREATEST EFFECT ON ON THE ACCURACY OF EARTHWORK QUANTITIES. IT IS COMPUTED BY DIVIDING THE ALGEBRAIC SUM OF THE INDIVIDUAL ERRORS BY THE NUMBER OF POINTS TESTED. ANOTHER MEASURE OF ACCURACY IS THE STANDARD DEVIATION OR MEAN SQUARE ERROR. IT IS DEFINED AS THE SQUARE ROOT OF THE AVERAGE OF THE SQUARE DEVIATIONS FROM THE MEAN. STUDY AND ANALYSIS OF PHOTOGRAMMETRIC ERRORS IN NUMEROUS LARGE-SCALE CONTOUR MAPS HAVE INDICATED THE FOLLOWING CHARACTERISTICS: (1) THERE ARE RELATIVELY FEW LARGE INDIVIDUAL BLENDERS IN PHOTOGRAMMETRIC MEASUREMENT, (2) SYSTEMATIC ERRORS ARE NOT CONSTANT BUT TEND TO VARY FROM MODEL TO MODEL AND EVEN WITHIN INDIVIDUAL STEREO MODELS, (3) THE ARITHMETIC MEAN OF THE ERRORS OF A REPRESENTATIVE SAMPLE PROVIDES A GOOD INDICATION OF THE AVERAGE OF THE SYSTEMATIC ERRORS. DATA DEVELOPED BY THE STUDY LEAD TO THE FOLLOWING CONCLUSIONS: (1) THE MOST IMPORTANT FACTOR IN THE ACCURACY OF EARTHWORK QUANTITIES IS THE VERTICAL ACCURACY OF THE SURVEY MEASUREMENTS, (2) PHOTOGRAMMETRIC SURVEYS ARE SUBJECT TO RELATIVELY SMALL SYSTEMATIC ERRORS, (3) USE OF PHOTOGRAMMETRIC SURVEYS FOR PAY QUANTITIES IS QUESTIONABLE UNLESS THEY ARE CHECKED BY STATISTICAL COMPARISION WITH AN ACCURATE FIELD PROFILE, (4) THE GREATEST SAVING IN MANPOWER IN OBTAINING EARTHWORK QUANTITIES WHICH CAN BE ACHIEVED IS DEVELOPMENT OF A METHOD OF UTILIZING PHOTOGRAMMETRIC QUANTITIES FOR PAYMENT, (5) ADJUSTED QUANTITIES FROM ALL OF THE PHOTOGRAMMETRIC SURVEYS WERE WITHIN LIMITS GENERALLY CONSIDERED TOLERABLE FOR PAY QUANTITIES, AND (6) THE METHOD OF ADJUSTING PHOTOGRAMMETRIC QUANTITIES BY USE OF A CENTERLINE PROFILE APPEARS TO HAVE CONSIDERABLE POTENTIAL VALUE AS A MEANS OF OBTAINING PAY QUANTITIES WITH A MINIMUM EXPENDITURE OF MANPOWER.

Media Info

  • Monograph Title: Photogrammetry: developments and applications, 1959
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00202715
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Sep 9 1994 12:00AM