24 
‘9 
are carried out by a group of specialists in the central administ- 
ration. A basic training in photo interpretation has also been 
given to the regional highway designers. 
4. FINAL DESIGN 
In this stage the use of photogrammetry concerns either the pro- 
duction of large-scale maps (1:500 or 1:1 000) for the detailed 
design of interchanges, bridges, etc, or numerical measurements 
of longitudinal profiles, cross-sections or digital terrain mo- 
dels. 
  
  
The maps are produced in a conventional photogrammetric way. The 
photography scale is generally 1:4 000 - 1:6 000. The planimetric 
control is arranged as a traverse close to the road centre line 
and with an average sidelength of about 100 - 200 metres. This 
traverse is used partly as planimetric control and partly as refe- 0 
rence points for setting out the road centre line. Vertical cont- 
rol is established by levelling. 
4.1 Numerical Measurements 
  
4.1.1 Longitudinal profiles and cross-sections 
These measurements are made in stereo plotters supplied with a 
device for automatic recording of model coordinates on punched 
paper tape (Wild AIO with Ek8 or Wild A8 with SAAB UE-211-1). 
The road centre-line and necessary cross-sections are drawn at the 
scale 1:500 or 1:1 000 together with planimetric control points 
in an automatic plotter (Kongsberg, Kingmatic). The "map" is ad- 
justed on the plotting table of the stereo plotter. Simply by fol- 
lowing the drawn lines with a profiloscope the longitudinal pro- 
file and the cross-sections can be identified in the stereo model | 
and accordingly measured and recorded. A1] control points are also 0 
measured and recorded. À transformation between model coordinates 
and ground coordinates is made first as a check in a desk calcu- 
lator Hewlett-Packard 9820 with a paper tape reader (Facit 4021) 
and then finally in the computer where all measured data are 
transformed. 
The requirements on height accuracy are high in this type of mea- 
surements. Attention must be paid especially to systematic errors. 
The data programs therefore include numerical corrections of the 
model coordinates before transformation to ground coordinates. 
Measurement of cross-sections means that a large number of data. 
is handled. It is most important that the data programs have built- 
in checks of the input data. The program used at the Road Administ- 
ration checks the planimetric and vertical position of every mea- 
sured point. In the planimetric control it is checked that the 
measured points are located within a tolerance corridor around the 
theoretical position of the cross-sections. The arithmetic and * 
square means are given in the out-put. See figure 1. 
Figure |. 
In the ve 
tion are 
The choic 
of cross- 
and size 
at the Ro 
an estima 
(Cpu) and 
ding cost 
ded as an 
have been 
terrestri 
A full-sc 
crease th 
Con/Cr 
15° 4 
to^ d- — 
  
Figure 2.