During the period 1960—64 the application was stabilized in several
countries and different working-procedures or systems were developed.
There were no longer any questions on the possibilities of using pho-
togrammetry in highway design. Instead the problems of fitting the in-
formation sources into the design procedure occupied a great deal of the
development capacity.
The procedure of highway design is all over the world today separated
into three different phases, namely preliminary location survey, prelimi-
nary design and final design.
The requirements of terrain-information differ between these three
phases. It is easily understood that the requirements of details become
stronger towards the last phase and also that in the first and second
phase a survey of the area in question is more adequate.
From those points of view it is quite obvious that photogrammetry has
been more utilized in location survey and in preliminary design. The
requirements of accuracy in planimetry and in elevation have been quite
fulfilled and the photographs themselves have afforded all necessary
terrain details. In the Swedish system e. g. the Balplex-model has be-
come an excellent aid for locating different alternative centerlines, with-
out time-consuming and expensive mapping. (14), II: 5.
Final design
In the phase of final design, however, the development of the appli-
cation has been more weak. This fact may be due to several reasons.
One reason is, that it is very difficult to fix accuracy specifications
for the terrain datas in the final phase. These specifications must content
requirements of accuracy as well for mass-quantities as for construction
oO
USA but on an international level the specifications still remain un-
elements. Requirements have been published in some countries e. g.
solved.
The extremely rapid growth of computors and computing systems has
also meant a great step forward in rationalizing the design procedure
and maybe most of the development capacity has been devoted to that
field, and therefore the remaining capacity has not been enough for
activity in the field of photogrammetry.
À third reason is that there still remains a large research work for
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