25 
x = measured points 
road centre line 
  
Figure 1. The positions of the measured points are checked 
against the theoretical position of the cross-sec- 
tion. 
In the vertical control the gradient changes within a cross-sec- 
tion are checked. 
The choice between terrestrial and photogrammetric measurements 
of cross-sections depends mainly on ground vegetation, topography 
and size of the project. The result of a study on this problem 
at the Road Administration is shown in figure 2. The curves give 
an estimation of the relation between costs for photogrammetric 
(Cpu) and terrestrial (CT) measurement of cross-sections inclu- 
ding costs for calculation of cut and fill. They are to be regar- 
ded as an aid for planning. The assumptions listed in table 1 
have been made for a twolane road. It is also assumed that the 
terrestrial measurement is made by levels or optical tacheometers. 
A full-scale use of electro-optical tachemeters will no doubt in- 
crease the efficiency of the terrestrial measurements. 
Ceu/ C1 
A^ 
20" 
Flat terrain 
Normal terrain 
fin N CN 
Rough terrain 
® 
| 
  
  
- Road length 
0.5 r T 7 > = {km) 
1 2 .3 á 5-6 7 8 9 10 
4 
Figure 2. Relation between Costs for Photogrammetric (Cpy) and 
Terrestrial (Cr). Measurement of Cross Profiles in- 
cluding Costs for Calculation of Cut and Fill.