46 
alinement (horizontal and vertical) and the highway cross sections, are com- 
bined by appropriate programing and used in the computers to ascertain the 
volumes of excavation and embankment, to achieve the best balance in use of 
earth materials, to determine where and how much borrow is required, and to 
compute the overhaul on excavation and borrow. All needed determinations are 
accomplished quickly, once the basic dimensional data and design criteria are 
appropriately recorded and converted into computer language. Electronic com- 
putation methods are especially applicable for the solution of each highway 
engineering problem which is extensive and complex, contains many sequential 
repetitions utilizing numerous types of input data, and the answer to which 
must be compared with the answers to several similar problems, such as ascer- 
taining grading and other quantities on numerous alinements (horizontal and 
vertical) and positions thereof, including the use of variable width medians 
and variable levels for the opposing traffic lanes of divided highways. 
Actually, an electronic computer is an effective repository of initial 
input digital data and contains a specific scheme for associating, classify- 
ing,and arranging that data; and the means of accomplishing the desired asso- 
ciation, classification, and arrangement, and of giving the arranged data as 
output to the suppliers of the initial data. Consequently, the highway engi- 
neering users of high-speed electronic digital computers are on "the uphill 
side” of any problem that can be defined in detail mathematically and can be 
programed. Among such users of electronic computers, it is recognized there 
is need for knowledge concerning the programs that are available and are appli- 
cable to specific engineering problems. Exchanging programs, after they have 
been prepared and tested by use, is beneficial to all concerned. But once an 
electronic computer program has been prepared, all input data must be arranged 
in precisely the same form as initially established; also output data will be 
recorded in the form devised according to concepts first attained regarding 
ultimate needs. Should conditions or situations be encountered subsequently, 
which are different from the original concepts, essential changes are made in 
the computer program. Input data are altered and output data achieved which 
are commensurate with the new requirements. The users of existing electronic 
computer programs, however, should be on guard and be aware of the circum- 
stances in which & particular computer program may not fulfill specific require- 
ments. 
One of our next needs from electronics is automatic plotting from digital 
data on punched cards, perforated tape, magnetic tape, or appropriate combi- 
nations thereof. This might be accomplished by use of & precision coordinato- 
graph electronically guided and operated to plot control points, contours, 
planimetry, profile and cross sections, and other representations, as needed. 
PROCUREMENT OF AERIAL PHOTOGRAPHS AND 
PHOTOGRAMMETRICALLY COMPILED MAPS BY CONTRACT 
Aerial surveys for highway engineering purposes would have been more dif- 
ficult, slower in getting started and becoming accepted practice, and retarded 
in enlargement of the scope of their applications, had it not been for photo- 
grammetric engineering firms being ready and willing to take the aerial photo- 
graphs, make the essential ground control surveys, and compile the maps needed 
by highway engineering organizations. The availability and willingness of 
these firms, however, were not assurances that highway departments would obtain 
from them exactly what would be the most serviceable photography and maps. 
Reasons for this situation were that, in the beginning, highway engineers were 
not as well aware, as desirable, with the potentialities of aerial surveys. 
Also, specialists on the staffs of photogrammetric firms were not always aware 
of what the highway engineer needed for use in each of the several stages of 
highway engineering. 
An uncertain highway engineer would ask for advice from a representative 
of a photogrammetric engineering firm. On such occasions, the forthright