1. THE SURVEY 
The survey is divided in two phases: in the first it has been 
organized and realized a network to move from the local 
system to the Italian Geodetic Datum, in the second it has been 
realized the survey of the detail. 
1.1 The realization of the network to support the survey 
of the different quarries 
The choice to adopt the GPS instrumentation is justified by the 
advantages respect to the traditional methodology which 
consists in the use of the total station to connect the vertices 
materialized inside the quarry surface to the vertices belonging 
to the Italian Geodetic Datum. GPS system allows a 
standardization of the procedures of datum, which are 
independent from the typology of the quarry and, in part, from 
the disposition in the territory of the vertices of the reference 
network. 
The procedures and methodologies here tested in the different 
case-studio can be generalized to the all cases of quarry survey. 
It has been defined an approach to carry out an agile survey 
system: this approach can be easy realized and verified with 
the instruments and software of data processing today available 
in sale. 
To guaranty the precision requested in the GPS network it 
must be used a static approach with the analysis of the 
differences of phases of the carrier wave. 
The characteristics of the instrumentation and the modality of 
use are described as follows. 
GPS receiver. 
It must be used the double frequencies, L1/L2, receivers with 
registration of the “C/A” code on the carrier LI. The double 
frequencies receivers allow to minimize the influence of the 
ionospheric component: the course of the electromagnetic wave 
between the satellites and the receivers isn’t the same. 
To obtain the contemporary evaluation of three independent 
baselines were implied 4 receivers with double frequencies 
antennas. 
The receivers have to be programmed with a cut-off angle of 15 
degree and with a sampling rate of 15 sec. 
It is also necessary that at least 4 satellites must to be always 
contemporary viewable with GDOP (Global Diluition of 
Precision) * 5. 
The Session of measuring (the time interval in which the 
receiver are contemporary working) depends on the distance 
length of the baseline, and, on the hypothesis of 5 satellites, 
the time acquisition is 15 sec. 
Particularly for each receiver 5 difference of phases relative to 
the 5 satellite are measured: from these differences of phases 
are determined the differences between the two receivers and 
the different satellites, and trough these are obtained the five 
double differences; of these observations only four can be 
considered as independent. For this reason in one minute 16 
observations must be considered . 
To assure a good local redundancy, in order to allow in the 
adjustment the localisation of the observations affected by 
eventual rough errors, the number of baselines which converge 
to each vertices must be /3. 
Generally the scheme of the survey will be composed by a four 
side polygon of which are measured 6 baselines to each point 
(the common side between the two four side polygon is 
determined two times). 
To maintain an equal time of observation among the different 
sessions, the polygon was built with an almost regular length 
of baselines. 
The contemporary use of four GPS allows to survey, for each 
session of measure, 3 independent baselines; the determination 
of each polygon is made with 2 sessions of measure that 
requires the repositioning of the antennas on the vertices. The 
high of the antenna must be acquired measuring in three 
different positions the slope distance between the vertices and 
the three position of the ground plane. 
Once completed the survey of each four side polygon the two 
queues receivers must move forward while the others have to 
remain fixed. The other vertices of the network (and the 
secondary GPS vertices) can be surveyed through independent 
session of measure and comiected to each one on the 3 vertices 
of a four side polygon. 
This schema requires 3 fixed receivers on three vertices of the 
4 side polygon and a third mobile receiver. On these points it is 
possible to make two session consequently, repositioning the 
GPS antenna as explained. 
The vertices of the network must be materialized in the way to 
remain in good conditions in the time. A good quality of 
monographs, containing pictures and the point co-ordinates 
have to be made. 
1.1.1 The survey of the fist order vertices 
The co-ordinate system to which refer the vertices of the 
network is the Gauss-Boaga system (Italian National Datum): 
Cartesian co-ordinate Est-North and for the height respect to 
the medium sea-level. It is possible to determine the last one 
applying the corrections to the ellipsoid height coming from the 
satellite measures with the data, locally estimated, of the 
undulation of the Geoid or using the corrections estimated 
using the benchmark of the IGM (Istituto Geografico Militare) 
network or the local cartography of the municipality near the 
quarry: in this case they have to be propagated using the 
traditional topographic methodology, that’s to say the 
geometric levelling or the trigonometric one. 
To test the results of the Est-North co-ordinates of the vertices 
of the quarry with the GPS approach, these co-ordinates are