1. An extremely precise field survey used as the true 
values for comparison of other methods. 
2. A field survey by standard highway design procedures. 
3. A survey using cross section data derived from a 
photogrammetric 2 ft. contour interval map. 
4. À survey using cross section data read directly in 
the photogrammetric stereo model, 
The test results showed conclusively: 
1. Earthwork computed from photogrammetric cross 
sections without adjustment to field surveyed 
elevations varied from the true quantities by 2 1/2 
to 3 per cent. 
2. Earthwork computed from cross sections deduced from 
a 2 ft. contour interval map was as good as that i 
obtained from cross sections read directly in the d 
stereo model, Io 
3. Earthwork computed from photogrammetric cross p 
sections, which were adjusted to a center line Lh 
profile surveyed in the field, varied from the true 
quantities by 0.5 per cent. 
4. Earthwork computed from adjusted photogrammetric 
cross sections was closer to the true values than 
that obtained from normal field survey methods. 
It should be noted that in the standard procedures out- hl 
lined, the center line profile is surveyed in the field before d 
the cross section data are read from the large scale photo- ul 
grammetric stereo models. There is little room for doubt, | 
therefore, that highway designs produced by the photogrammetric- 
electronic methods are sufficiently accurate to meet all re- 
quirements, 
  
  
ECONOMY a 
A completely integrated photogrammetric-electronic system 
is complicated. It requires efficient management and careful 
balancing of system components and programs. Cost comparisons j 
obtained by various organizations may be expected to vary con- I 
siderably depending upon their efficiency and the extent to | 
which they have implemented the system. However, the California | 
tests provided some significant figures: li 
  
  
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