510 
SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962 
it is to them that attention must be directed if engineering application is con 
templated. Meanwhile, what are the engineering requirements? 
Organic terrain and engineering purpose 
To discuss methodology as pertaining to engineering lacks point, unless 
method is aligned with purpose. The latter is, in fact, primary. Although one 
might postulate many kinds and degrees of it, it is perhaps more conveniently 
anticipated in the light of experience rather than of probability. The writer, 
over the last fifteen years, has encountered eight major aspects of engineering 
planning connected with exploitation of organic terrain. They will be discussed 
in what is judged to be descending order of importance. 
Off-road access 
To effect overland communication where no roads exist, is designated the 
most essential purpose at the present time so far as Canadian organic terrain 
is concerned. It is important not only because of transportation and survey, 
but also because it is basic to implementing developmental schemes generally. 
To plan for it, the terms of operation and the types of vehicles involved must be 
known. Permanent or temporary routes of travel then may be established 
according to design based on the factors in table 1. 
Table 1. Planning for off-road 
access 
Terrain factor 
Implication 
Vegetal cover 
Peat category (1 to 16) [5] 
Microtopography 
(surface and sub-surface) 
Macrotopography 
Obstruction, corduroy, subsidence 
Bearing strength, shear, water-ice content, coherence, 
elasticity, consolidation, stability, drainage 
Vehicle selection, vehicle performance 
Logistics 
Foundation 
Selection and assessment of foundation requires procedures which differ 
depending upon the circumstances for which the foundation is required. Inter 
pretation is commonly based on the relationships expressed in table 2. 
Table 2. Foundation evaluation 
Terrain factor 
Implication 
Vegetal cover 
Peat category (1 to 16) [5] 
Microtopography 
Macrotopography 
Reconnaissance, predicting peat type and depth 
Mineral sublayer, establishing test sites 
Soil sampling, ice relations 
Temperature range, drainage 
Stability of peat body