—400 m in breadth about this road-line. In addition to this details, 
in the horizontal plane are mapped over a somewhat broader area inas- 
much as this may be called for by changes in estate with subsequent 
readjustment occasioned by the road project. 
The map is produced in the stereoautograph Wild A 8 from the same 
pictures and with the same control points as were used for the Balplex 
planning. 
This map 1s then used by the road-planner in the more detailed fitt- 
ing in of the road in the terrain, and the staking-out data are obtained 
in relation to the polygon system which is shown on the map. Where 
the detail polygon system has not been signalized before the photogra- 
phing but is only measured in connection with the detail planning of 
the road it is marked in separately on the map. The polygon system is 
in connection with the measurement linked to the tellurometer polygon 
system, and as these two systems are then united, the mapping of the 
polygon points on the finished map will not constitute any problem. 
It may perhaps seem rather bothersome to work first on the planning 
in Balplex and then on a detail map. The reason for this method is, 
however, that with the help of Balplex it is possible rapidly and cheaply 
to run through a number of alternatives without mapping; only the 
most interesting alternatives are shown, and with the help of economic- 
and technical- analysis and synthesis one obtains a main route, and 
then the detail-mapping can be restrichted to this route. One is thus 
saved a lot of unnecessary and uninteresting mapping work, 
In addition to this we have what is perhaps the most important con- 
sideration in this connection, viz., as pointed out above, the possibility 
of planning direct in nature in the photogrammetric model. 
This method at the stage of the preliminary planning implies a great 
saving in time and expenditure on the way to an optimal result of the 
road-planning. Conceivable alternatives can be quickly investigated, and 
when the planning engineer submits the plan he knows that the result 
he is putting forward is the best possible and he is at the same time in 
a position to show why this is so. 
Before the final acceptance of the preliminary plan it is in the ma]o- 
rity of cases necessary to stake out the road-line at least roughly in the 
terrain. If the road-planning has been carried out in the way described 
above this staking out constitutes in principle only a problem of mark- 
ing out from the polygon points or from details of the map. The adjust- 
ments of the road-line that are required in connection with the staking 
out are restricted to a minimum. 
It is difficult to show just how great is the saving entailed, as the 
result must be judged with reference to what has been investigated; it 
is clear, however, that if the assessment were to be made solely with 
reference to the amount of time spent for the corresponding work in 
the field, the saving in time and expenditure in this connection would 
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