and grade lines, cross sections, and mass diagrams. The com- 
puter determines each of these items in terms of x and y 
coordinates which can be plotted on paper. 
An electronic drafting instrument, such as the Benson- 
Lehner Electroplotter Model H (Figure 3) or Electronics 
Associates Line Plotter, accepts coordinate data on cards or 
tape and automatically plots the points and connects them by 
straight lines at the rate of up to twenty lines per minute. 
The next step in increasing the efficiency of the highway 
planning exercise was to make use of the time tested technique 
of aerial triangulation to eliminate much of the field survey 
required to control the photogrammetric mapping. This procedure 
uses the photographs themselves to extend control from a few 
ground points known at the ends of the flight to provide suf- 
ficient control for the mapping of all stereoscopic models in 
the strip. It requires the use of a so-called first order 
plotting instrument. The ground coordinates determined by such 
an instrument characteristically exhibit a systematic error 
which can be eliminated by fitting a polynomial error surface 
to the instrumentally determined coordinates of the given 
ground points. This is another exercise for the electronic 
computer. 
This is about the state of the art as presently employed. 
The degree of sophistication of programs varies from company to 
company, and is often dictated by the capacity of the computer 
employed. It might be well to list the computing programs which 
are employed in the procedure. 
1l. Computation and adjustment of field traverse and 
level nets. 
2. Adjustment of aerial triangulation performed in 
first order plotter. 
3. Computation of horizontal and vertical curves. 
4. Computation of longitudinal and transverse profiles. 
5. Development of design template for each cross 
section, taking into account berms, ditches, side 
slopes, and superelevation. 
6. Computation of cross section areas and slope stake 
coordinates. 
7. Computation of earthwork volumes between cross 
sections, and seeding areas.