REPORT OF COMMISSION VII 
G VI1-49 
of the proposed route with regard to topography, build-up areas, cultivated 
areas, estate boundaries, and other factors which appear more or less clearly 
from the photograph without the application of special photographic interpreta 
tion techniques. 
In the forested areas of both Norway and Sweden, photography is used ex 
tensively in selecting routes for logging roads. 
These photographs are also used as field maps for the personnel constructing 
the roads. Since in these areas, aerial photography is regularly taken for forest 
estimation purposes, prints are readily available for road planning. 
THE HIGHWAY PLANNING PROCESS 
In the United States, both photogrammetry and photographic interpretation 
are becoming more and more an integral part of the highway planning process. 
Many of the State highway departments maintain photogrammetric sections 
in which photogrammetry and photographic interpretation are accomplished. 
Also the various types of specialist engineers who participate in highway design 
and construction are becoming trained in the use of photography as a base for 
their various analyses. 
Pryor (1954) lists the eight stages in the highway engineering cycle in which 
aerial photographic analysis is used: 
1. Planning; 
2. Reconnaissance of area and determination of route possibilities; 
3. Reconnaissance of route alternatives and their comparison in selecting 
the best route; 
4. Preliminary survey of the selected route for design of the location and 
preparation of plans; 
5. The location survey staking of the highway on the ground for construc 
tion; 
6. Condition and inventory surveys; 
7. Maintenance and betterment surveys; 
8. Surveys for highway improvement and reconstruction. 
Mr. Pryor, in the same paper, gives a most concise and informative descrip 
tion of the procedure followed in analyzing photography to provide information 
for use in these engineering phases. This section of his paper is reproduced below. 
Note that while certain photogrammetric techniques are involved, the process 
as presented here is basically one of photographic interpretation. 
“Sequential steps in the full employment of photogrammetry in each stage will 
usually follow a logical pattern. These steps are not rigid. Deviation is possible whenever 
situations and exigencies require it. Usually the steps are eight in number. Progressively, 
they will provide, in both qualitative and quantitative form, nearly all that is needed 
for making most highway engineering decisions. 
“The first step is identification or recognition of images on the aerial photographs. The 
identification is restricted generally to those images which will have an influence on deci 
sions for specific purposes. 
“The second step is often inseparable from identification or recognition. It is 
interpretation of the images, their pattern, their relationship one to another and to the 
highway engineering problems they represent. 
“The third step is number. This is the count of all identified and interpreted images 
either individually or by groups, which must be considered in making decisions while 
solving the highway engineering problems. Like the first and second steps, the third 
and fourth are often inseparable. 
“Essentially, step four is the measurement of position, shape and size—usually