TERRESTRIAL LASER SCANNING FOR DEFORMATION MONITORING 
- LOAD TESTS ON THE FELSENAU VIADUCT (CH) 
H.-M. Zogg *, H. Ingensand 
ETH Zurich, Institute of Geodesy and Photogrammetry, Zurich, Switzerland - (zogg, ingensand)@geod.baug.ethz.ch 
Commission V, WgS V/3 
KEY WORDS: Terrestrial laser scanning, Engineering surveying, Deformation monitoring, Point cloud processing 
ABSTRACT: 
In conjunction with future renovation work on the 33-year-old Felsenau viaduct (CH), which is part of the Swiss highway Al and 
one of the most remarkable concrete bridge structures in Switzerland, load tests were performed for evaluating the fatigue resistance 
and refining the analytical models. The bridge girder was therefore loaded with more than 100 tons. The Institute of Geodesy and 
Photogrammetry at ETH Zurich was responsible for deformation monitoring during the load tests. In addition to traditional 
surveying methods such as precise levelling and tacheometry, terrestrial laser scanning was performed for the detection of 
deformations. This paper presents unique load tests on the Felsenau viaduct as well as results of deformation monitoring with focus 
on measurements by terrestrial laser scanning. Furthermore, a comparison of terrestrial laser scanning and precise levelling is 
described. 
KURZFASSUNG: 
Im Zusammenhang mit zukünftigen Renovationsarbeiten am 33-jährigen Felsenau-Viadukt (CH) wurden Belastungsversuche zur 
Untersuchung von Ermüdungsproblemen und zur Verbesserung der Berechnungsmodelle durchgeführt. Der Felsenau-Viadukt gehört 
zur schweizerischen Nationalstrasse Al und gilt als eines der markantesten Betonbauwerke der Schweiz. Der Viadukt wurde mit 
mehr als 100 Tonnen belastet. Das Institut für Geodäsie und Photogrammetrie der ETH Zürich war für die Bestimmung der 
Deformationen verantwortlich. Neben traditionellen Messmethoden wie Präzisionsnivellement und Tachymetrie wurde auch 
terrestrisches Laserscanning für die Bestimmung der Deformationen eingesetzt. Im Folgenden werden dieser einzigartige 
Belastungsversuch sowie die Resultate der Deformationsmessungen vorgestellt. Dabei liegt der Fokus auf den Messungen mittels 
terrestrischem Laserscanning. Ebenso werden die Resultate der Messungen mittels terrestrischem Laserscanner und 
Präzisionsnivellement miteinander verglichen. 
1. INTRODUCTION 
The Felsenau viaduct of the Swiss highway A1 is situated north 
of Berne, the Swiss capital. The average daily traffic on the six- 
lane viaduct is about lOO’OOO vehicles. Trucks represent an 
important part of all vehicles. Furthermore, rush hour peaks are 
significant due to traffic generated by the city of Berne. The 33- 
year-old viaduct has a length of 1116 m and traverses the Aare 
valley at a height of up to 60 m (Figure 1). This viaduct is a 
span bridge made of concrete and is one of the most remarkable 
bridge structures in Switzerland. The carriageway lies on 
cantilever slabs with 26.2 m wide cross-sections. Additionally, 
piers with cross-sections of about 7.5 m carry the slabs. The 
span length of the viaduct between piers is up to 156 m for the 
large middle sections. 
In conjunction with an overall renovation of the tangential 
highway north of Berne, the Felsenau viaduct was subject to 
detailed investigations. Due to a large rising of the traffic 
volume within the last years, the viaduct does not fulfil the 
safety requirements any longer. Furthermore, the transversely 
prestressed cantilever slabs may suffer from fatigue problems. 
In order to obtain a reliable basis for the evaluation of the 
fatigue resistance and to refine the analytical models, additional 
load tests were performed on the Felsenau viaduct. While 
loading the viaduct, the arising deformations were monitored 
and the results were valuable for further analyses. 
For two nights in spring 2007, the Felsenau viaduct was closed 
for traffic, and load test were performed. Two tanks with an 
approximate weight of 54 tons each were used to load the 
cantilever slabs. The Institute of Geodesy and Photogrammetry 
at ETH Zurich (IGP) was responsible for the monitoring of the 
Felsenau viaduct with regard to deformations. Besides 
traditional surveying methods as precise levelling and 
tacheometry, terrestrial laser scanning (TLS) was established 
for the detection of potential deformations of the viaduct, of the 
cantilever slabs in particular. 
Until now, TLS has been introduced for deformation 
monitoring of different applications in the field of engineering 
geodesy. (Tsakiri et al., 2006) discuss the possibilities of TLS 
for deformation monitoring in general and compare the 
monitoring of selected targets with the area-wide monitoring. 
The main advantage of deformation monitoring by TLS is the 
full surface representation. A discretisation of the object by 
reference points is not required. This enables the detection of 
unexpected deformations. 
Deformation monitoring by TLS has been accomplished for 
several projects as in tunnels, e.g. (Lindenbergh et al., 2005) 
Corresponding author 
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