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is required over limited areas. The requirements on geologi- 
cal-geotechnical information follow the same principles in 
the design process. 
In the practical work it is not always possible or convenient 
to keep strict limits between the different design stages for 
every project, due to local conditions and problems. It is, 
however, for efficiency in design, important to arrange and 
plan the process along the main principles. 
As mentioned above the application of photogrammetry to High- 
way Design depends on whether there exist topographic maps of 
an acceptable quality and at a suitable scale. The principles 
that are discussed below presuppose that no acceptable topo- 
graphic maps exist or are available. In practice the different 
stages may then be coordinated using the maps that do exist. 
1.1 Route Location 
The main considerations of the highway network or of the single 
road are defined in this stage. Therefore a preliminary fitting 
of the requirements of the forecasted traffic to the topographi- 
cal an geological conditions of the terrain is needed in order 
to optimize the total cost function. The actual cost function 
is principally divided into construction cost and cost of ve- 
hicle operation. These two cost functions are correlated with 
the alignment of the road in the terrain. 
In the route location stage it is a question of principles be- 
hind the forming of the highway network or the laying out of 
the single road and therefore a preliminary analysis of the 
topography and geology of the terrain is for the most part suf- 
ficient. This analysis must, however, cover very wide areas to 
give the possibility of evaluating all alternative solutions. 
The terrain studies can be made by photo interpretation of the 
geology and topography combined with preliminary measurements 
of longitudinal profiles along the different possible center- 
lines. 
One of the main tasks of the analysis of the terrain in the 
location stage is to delimit areas, that because of their