43 
Table 6. — Accuracy in measurement of profile and cross sections 
  
  
  
Feet Meters 
Not to exceed scale, Not to exceed the 
Error in feet to one inch, denominator of the 
of finished maps by representative frac- 
tion expressing scale 
of finished maps by 
  
  
  
Mean 1/600 1/24,000 
Average 1/200 1/8,000 
Maximum 1/60 1/2,400 
  
  
  
  
  
Accuracy and completeness tests of planimetric maps, 
and profile and cross sections 
Principles applying in the direct procedure to the accuracy of planimet- 
ric features and their tests are also applicable to planimetric features in 
this similar phase of indirect procedure. 
The accuracy of profile and cross sections is determined by accurate 
ground-surveyed traverse on each of several randomly selected cross sections 
and segments of the centerline, and by an accurate profile measured on the 
ground along each of such traverses. 
Engineering use of photographs, planimetric maps, 
and profile and cross sections 
In this second engineering use, in the indirect procedure, of photographs 
and planimetric maps compiled from second photography of the route, profile 
and cross sections measured from the stereoscopic models are also used. The 
aerial photographs, plenimetric maps, and profile and cross sections are used 
simultaneously in some steps and alternately in others. As in the direct pro- 
cedure, the photographs are examined stereoscopically and interpreted and 
analyzed to obtain the needed qualitative information. The planimetric maps 
and staked centerline provide data on position and direction, and the profile 
and cross sections of the ground contain the essential dimensions regarding 
shape, size, and position needed in design of the highway gradients, includ- 
ing vertical curves, the positioning of the highway cross sections at sta- 
tioning points and breaks in ground line slope, and computation of grading 
quantities. Also, as in the direct procedure, the service standards estab- 
lished by the class of highway govern in detail all engineering work subse- 
quently performed. 
Since the position and shape of the centerline was designed in the first 
phase of this indirect procedure, it is changed in this second phase only when 
the additional, more detailed, and larger scale dimensional data and qualita- 
tive information, now available, prove such is necessary. 
Subsequent designing of the highway is a continuation of the design accom- 
plished in the initial design phase. The design of the highway's physical, 
geometric, and esthetic aspects, by comparison procedures, is largely confined 
to completion of the detailed design, making refinements, balancing grading 
quantities where feasible, and computing &ll construction quantities. 
In designing the highway, the principles and sequential procedures are 
essentially the same as in the direct procedure, except that the profile and 
cross sections used are those measured photogrammetrically on the stereomodels