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The capable and proficient locator had had years of experience in recon- 
naissance, preliminary, and location surveys; in highway design; and in high- 
way construction and maintenance. For lack of time, he seldom determined route 
alternatives to compare one with another. His justifications for directly mak- 
ing one route determination only were that highway location was an art acquired 
by experience and sustained by inherent aptitudes. 
Based on what the locator saw, on what his previous personal experiences 
were in highway location, and on his own judgment, he flagged on the ground for 
preliminary survey the route he considered to be the most practicable. The 
locator, of course, had ground survey parties to make the preliminary survey 
where he designated. They ran the traverse, measured its profile and the cross 
sections, made other essential measurements, and kept field notes thereon; and 
noted the character of topography, ground conditions, drainage, land use, and 
the like for utilization in design. 
Of course, when a highway location was determined solely by working on the 
ground, its quality could not be verified by others except by their reviewing 
it on the ground and making such additional route determinations as were nec- 
essary for achieving adequate comparisons and evaluations. This in effect 
meant a repetition of virtually all work completed by the initial locator. 
Such procedures were costly in both time and money. Consequently, the quality 
of route locations so determined, and their acceptance, were based largely on 
the reputed competence of the particular locator. But in actuality, even a 
highly competent locator might not be able to determine the best location, 
because of time limitations, weather conditions, or other interfering factors 
beyond his control. 
Weaknesses in the preceding practice have sometimes been revealed through 
comparisons made, not by direct intent, but because of a succession of 
unplanned events, such as follows: (1) need, before constructing the highway 
on the initial location, of extending the route beyond one or both of its orig- 
inal termini; or (2) postponement of construction for lack of funds and subse- 
quent changed conditions requiring better curvature, gradient, and cross sec- 
tion standards to satisfy needs for increased traffic services; or conversely, 
demanding construction of a road in minimum time and for the limited funds 
available, regardless of the extent to which standards must be reduced; or 
(3) the original locator could not complete the initial location work because 
he transferred, retired, resigned, or became indisposed. The succeeding loca- 
tor, before continuing rou where the preceding locator had ended his work, 
had to become familiar with conditions and accomplishments in relation to the 
old and new requirements. He had to review and, in some instances, duplicate 
a small or major portion of the previous locator's work before he could begin 
to perform the work required of him. Such review and duplication, whether 
accomplished on the ground or by utilization of aerial surveys, sometimes 
revealed the original route location was badly positioned in whole or in part, 
or at least could be improved. 
Whenever the route reviewing and additional surveying were done by aerial 
methods over a broad area from one terminal point to the other, the opportunity 
was afforded for easily and quickly determining every feasible highway location 
alternative. Thus many alternatives could be compared and the best one ascer- 
tained. Upon comparing the best route, as determined by aerial methods, with 
the original route location made by ground methods, it frequently became evi- 
dent that the quality of the latter's service standards were deficient and its 
positioning on the ground inferior to other possibilities. Before needed exten- 
sions and revisions could be made appropriately and economically, it was desir- 
able, and sometimes essential, to abandon part or all of the first surveyed 
route and locate another. Thus, it is evident that when engineers were working 
without the aid of aerial surveys, they were extremely handicapped, especially 
were ‘they lacking in time and capacity, if not funds, to make the thorough and 
comprehensive surveys that are now possible by aerial methods.