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2. ROUTE LOCATION 
In the route location stage the main considerations of the high- 
way network must be defined. The highway network has to be deve- 
loped in close relation to long-range plans for development of 
communities and land use. 
For this reason it is more important to get general and compre- 
hensive rather than detailed accurate information about topo- 
graphy, geology and land use over the wide areas that are in- 
volved. 
Topographic maps or aerial photographs in medium scales are the 
most common sources of topographic information. In Sweden there 
are two types of official maps that are generally used in the 
route location stage. One is the Topographic Map in the scale of 
1:50 000 containing contour lines with 5 m interval. The other 
is the Economic Map in the scale of 1:10 000. These maps are 
still being produced by the National Land Survey, and the whole 
of Sweden will not be covered with these maps until 1978. Econo- 
mic Maps include property boundaries but if produced before 1961 
they do not contain contour lines. This means that for rather 
large areas there is a lack of suitable maps. 
To overcome this problem aerial photography in the scale 1:30 000 
is carried out by the National Land Survey. The country is divi- 
ded into regions and for most regions the photography is repeated 
every seventh year. 
These photographs are being used where official maps are missing 
or are old. 
The evaluation of the photographs is made with simple photogram- 
metric instruments. Normally mirror stereoscopes are being used. 
Using Balplex Plotter, an instrument with optical projection, an 
overall view of the entire stereo model or a set of models is 
obtained. The Economic Map (1:10 000) is used for absolute orien- 
tation of the models. Sometimes it is necessary to make a supple- 
mentary field survey to get additional planimetric and elevation 
control. 
The topographic analysis of the area, including preliminary mea- 
surements of longitudinal profiles along feasible route locations 
may then be made directly in the stereo model. The result is often 
presented directly on the Economic Map. 
In 1974 a new public regulation on geodetic, photogrammetric and 
cartographic applications was issued. This means among other 
things that a close cooperation is requested between different 
public organizations acting in the same geographical area in 
questions concerning fundamental geodetic work, aerial photography 
and map production. 
This fact together with the fact that an essential part of road 
investments is allocated to communities will probably have the 
effect that a new type of basic maps for general planning purpo- 
Ses e.g. route location is needed.