Wherever the roads are primarily to provide service to the bordering 
lands, there are no imposed restrictions on access and all other traffic ser- 
vice standards are lower, in varying degree, than on the controlled access 
highways. Therefore the class of highway, established by its purpose, must 
be kept in mind throughout each of the stages of location and design to prop- 
erly, esthetically, and economically fit each highway into the many and vari- 
ous complex combinations of the configurations of the ground, its surface 
drainage, and man's uses of the land for effective movement of motor vehicles 
with convenience, comfort, and safety. 
In actuality, as aerial surveys are employed throughout each stage in 
highway engineering, the principles just presented are kept in mind by each 
specialist on the highway team and are utilized by him, as applicable in whole 
or in part, while he performs his particular portion of the work. Therefore, 
in developing this paper, aerial surveys could not be separated from the actual 
performance of the engineering and other work required. Moreover, in their 
broadest sense and extent, aerial surveys can be used beneficially in many 
ways, each separate way being chosen according to its applicability and to 
need--need for qualitative information, for quantitative data, and for ascer- 
taining and demonstrating significant relationships. These needs include 
illustrating situations, circumstances, problems, and their proposed solu- 
tions; and in obtaining in appropriate form a factual record for review, when 
and where essential, to ascertain the completeness and adequacy of solutions, 
and to make revisions, as necessary, when or where new requirements and/or 
changed situations or circumstances occur. 
It seemed pertinent first to discuss the nature of aerial photographs and 
of aerial surveys as used in highway work. Next, in an amplification of the 
specific working procedures in applying aerial surveys in the stages of highway 
engineering, each use-stage is preceded by a statement regarding the objectives 
and work accomplished through the advantageous employment of aerial surveys by 
the engineer specialists on the highway team. Within each stage there follows, 
in somewhat chronological order, the specific procedures which are, or can be, 
employed by the highway team in the performance of its engineering work. This 
is begun with the preliminary engineering stages--the stages in which the char- 
acter, quality, continuity, and lasting utility of a highway are determined by 
ascertaining and utilizing position, physical dimensions, and applicable qual- 
itative information--and concluded with some uses of aerial surveys in highway 
construction, maintenance, improvement, and reconstruction. Finally, a pres- 
entation is made regarding the procurement by contract of aerial photographs 
and photogrammetrically compiled maps. 
NATURE OF AERIAL PHOTOGRAPHS AND AERIAL SURVEYS FOR HIGHWAYS 
The uses of aerial photographs and aerial surveys for highway engineering 
are manifold. The great number of varied ways in which these means are aids 
to the highway team in ascertaining, solving and demonstrating its problems 
and their proposed solutions will be more easily understood if the nature of 
aerial photographs and aerial surveys for highways is first reviewed. 
Aerial Photographs 
  
When obtained at the appropriate scale, as governed by accuracy and detail 
requirements, aerial photographs are the basic source of qualitative informa- 
tion and quantitative data. The qualitative information is obtained by photo- 
graphic interpretation and analyses, and the quantitative data from photogram- 
metric measurements and delineations, including maps. Aerial photographs are 
records of the status and conditions within an area on a Specific date, and are 
easily adaptable and usable, both directly and indirectly, when and where 
necessary.