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(645) 
report is based. Special mention is extended to the representative of the Victo- 
rian Railways of Australia, to Professor Donald J. Belcher of Cornell Univer- 
sity, and to Mr. W. T. Pryor of the Bureau of Public Roads. 
Bibliography. 
Belcher, D. J. et al, “Highway Research Board Bulletin 46,” December, 1951. 
Colwell, R. N., K. E. Bradshaw, H. T. U. Smith, Ragnar Thoren and C. A. T. 
von Frijtag Drabbe, “Report of Commission VII (Photographic Interpre- 
tation) to the Intern. Society of Photogrammetry,” Photogrammetric Engg., 
Vol. 18, No. 3, pp. 375-452, June, 1952. 
Lundahl, A. C. et al., *Panel on Photographic Interpretation," Photogrammetric 
Engg. Vol. 18, No. 3, pp. 452-508, June, 1952. 
Pryor, William T. et al.; Symposium: “Photogrammetry as Applied to Highway 
Engineering," Photogrammetric Engineering Vol. 17, No. 1, pp. 111-180. 
March 1951. 
U.S. Geological Survey, *Aerial Photography of the United States," Fifth Edi- 
tion, 1951. 
USE OF AIR PHOTO INTERPRETATION FOR AIRFIELD 
ENGINEERING !) 
Maxim M. Elias. ?) 
Value of air photos. 
Air photos are valuable tools for the engineer and the geologist; they save 
time, effort, and materials when applied to siting, planning, and directing air- 
field construction. Air photos provide: (1) rapid coverage of large areas, (2) in- 
formation on areas inaccessible on the ground or accessible only with difficulty, 
and (3) a broad perspective and coordinated view of a site area. 
Where sites are to be selected from a large area, air photos are valuable for 
the initial reconnaissance. The entire area can be covered rapidly, and large 
parts that are obviously unsuitable can be eliminated from consideration. The 
more laborious ground search can therefore be limited to a few of the most 
likely localities. A preliminary estimate of the engineering problems of the area 
can be made from air photos and will further aid in planning the ground work 
and selecting the localities to be investigated. An approach to the analysis of 
broad areas of the United States was made in the studies on air-photo identifi- 
cation of soils produced in 1946 and 1948 for the Civil Aeronautics Administra- 
tion of the U. S. Department of Commerce (references 2 and 4). 
The greatest need for aerial photos is for surveying areas that are 
inaccessible on. the ground, such as those in arctic and desert regions. In the 
rugged Alaskan terrain, the Corps of Engineers, U. S. Army, and the U. 5. 
Geological Survey have made extensive use of air photos at airfield sites as well 
as for other engineering and scientific investigations (reference 1). 
Air photos are invaluable in time of war when military engineering projects 
1) Publication authorized by the Director, U.S. Geological Survey. 
2) Geologist, U.S. Geological Survey.