when the result of the evaluation consists of a map with con-
tours. The scale of the map is generally 1:10000 or 1:5000 and
the contour interval 10 or 5 m. Second order photogrammetric
equipments as Kelsh Plotter, Aviograph Wild B8 are mainly used
for the mapping.
A traffic-technical and traffic-economical analysis is required
as a basis for the choice between the different terrain corri-
dors. This analysis takes into account not only the influence of
the cost of construction and vehicle operation for the alterna-
tive solutions but also the fitting of the highway network into
the development of the community.
Such analysis are, however, not discussed in this report as they
do not have any essential influence on the system of the photo-
grammetric application.
1.2 Preliminary Design
The first part of this design stage consists of a systematiza-
tion and actualization of the result from the route location
stage concerning the actual terrain corridor. The result of the
design work of this stage is a centerline, analyzed in such de-
tail, that it is ready for setting out in the terrain. This means
that the actual alternative centerlines within the terrain corri-
dor are investigated concerning their preliminary horizontal and
vertical alignment, so that their cost functions, construction
and vehicle operation, can be analyzed together with their effects
upon the development of the community. Therefore, in this design
stage the requirements on a survey over wide areas within the
terrain corridors must be combined with requirements on geometri-
cal quality of the terrain data, that are adapted to the real
needs.
Areal photographs from 1500 m - 2000 m flying height are gene-
rally used in the preliminary design stage, depending on the in-
formation requirements. These image scales are more related to
the requirements on an overall view of wide areas than to the
requirements on geometric accuracy. Experience has, however, up
to now, shown that these photographs, evaluated in suitable
equipment, using a suitable technique, give an acceptable com-
promise between an overall view and geometrical accuracy.
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