oints: 
E 6) 
(7) 
(8) 
from : 
(9) 
cions 
^ this 
ne 
ated 
dient 8 % 
ent. 
12 
"8 
2 
Traverse AB, gives the shortest connection between road points 
l and 12. Its total length is 1041 m. with gradients between 
- 8% and + 8 % (see table 1). If for example a route had been 
selected with a constant gradient, then the road would have 
been much longer. Tracing AB, (see fig. 3) is 1275 m long with 
a very gently gradient of approximately 1 %.uphill. 
Such profiles of alternative traverses allow a comparison between 
section lengths, gradients, obstacles, etc. before a field check 
is carried out. An analysis of the cost for the construction of 
the roads, and the cost for the transport of the timber by trucks 
is necessary in order to decide upon the most economic route. 
Only the best traverse is interpreted in detail on the aerial 
photographs and tested out in the terrain 
Conclusion 
The procedure of road design and profile construction is very mich 
simplified when carried out with the help of large scale topographic 
mans or orthophotomaps with contours. Unfortunately such maps are 
often not available in less developed countries, and their construct- 
ion may be impossible because of lacking funds or facilities. 
In view of the great need for improving the infrastructure of so 
many forested areas aerial photography provides a relative cheap 
means to obtain the desired information for the planning of a 
road network, The aerial photographs should have a scale not 
smaller than 1 : 15,000,in order to allow sufficient discrimination 
between ground and forest canopy. The photography should be taken 
with a minimum on tip and tilt, so that rectification is not 
necessary. Through parallax measurements under a mirror stereoscope 
it is possible to design a road system,zeven in steep terrain. 
The techniques proposed in this paper allow a skilled ifterpreter 
to draw up a well documented proposal for the layout of a road 
network, that serves the multiple interests of the forest manager. 
Literature 
Chandra, R., 1976. Accessibility in tropical forests. 
Working paper on accessibility studies. 
FAO meeting, Rome. 
FAO, 1976 Reports on accessibility of tropical forest 
resource surveys. Nr.1, Madagaskar; Nr. 2, 
Argentina; Nr. 3, Gabon. 
Hallert, G, 1976 The application of aerial photointerpretation 
to road design in Sweden. 
ISP congress, Helsinki, 1976. 
Le Ngoc Quy, 1971  Aerophotogrammetrie in der Erschliessungs- 
planung und im Waldstrassenbau. 
Dissertation, University of Freiburg.