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Construction Process Monitoring at the New Berlin Main Station

Civil Engineering Applications

  1. Rosemarie Helmerich

Published Online: 15 SEP 2009

DOI: 10.1002/9780470061626.shm170

Encyclopedia of Structural Health Monitoring

Encyclopedia of Structural Health Monitoring

How to Cite

Helmerich, R. 2009. Construction Process Monitoring at the New Berlin Main Station. Encyclopedia of Structural Health Monitoring. .

Author Information

  1. BAM Federal Institute for Materials Research and Testing, Division VIII.2 Non-destructive Damage Assessment and Environmental Measurement Methods, Berlin, Germany

Publication History

  1. Published Online: 15 SEP 2009

1 Introduction

  1. Top of page
  2. Introduction
  3. Monitoring Concept
  4. Measurement Systems and Advanced Sensors
  5. Results
  6. Conclusions and Outlook
  7. Acknowledgments
  8. References

The six dead-end train stations of the first railway concept in Berlin, developed in the nineteenth century, were almost completely destroyed in World War II (Figure 1). The Lehrter Bahnhof, covered by a true arch roof, being one of the six dead-end railway stations, was destroyed too. After the reunification of Germany and the city of Berlin, the German railways (DB AG) developed a new concept with the New Berlin Main Station as a crossing of trans-European high-speed trains. The optimum location for a main station in the city center was found to be near the suburban train station Lehrter Bahnhof, which was rebuilt after the war.

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Figure 1. The former Lehrter Bahnhof was one of the six dead-end stations forming the railway system in the nineteenth century.

The architects Gerkan, Marg, and partners from Hamburg developed the architectural design for this most modern and large train station. Professor Schlaich, Bergermann, and partners from Stuttgart are responsible for the structural analysis and design.

In the center of Berlin, the new main station with a wide-spanning modern glass roof has been under construction since 2001 (Figure 2). In 2006, the station was taken into service as an important high-speed train crossing of the two international train corridors from Paris to Moscow and from Rome to Stockholm. The German railways, DB Station and Service AG, represented by DB Projektbau, owned the structure during construction.

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Figure 2. New modern main station Lehrter Bahnhof with flat glass arch roofs during construction in 2003.

1.1 Description of the Structure

The New Berlin Main Station is a complex structure. The supports of the interesting glass roof do not lead the load directly to foundations and soil, but use other static systems as the viaducts carrying platforms and tracks. The whole bridge viaduct has a length of about 680 m, and the width of the tracks in the station varies between 33 and 68 m [1]. Two of four reinforced concrete viaducts, carrying the east–west directed tracks for the international railway traffic, support the relatively flat glass roof that is up to 60 m wide. The railway station is located in a curve. That is the reason that each of the almost 8000 glass plates has a different geometry.

Partially prestressed concrete bridges in the east–west viaduct are crossing the north–south international passenger train line and have a larger span compared with the other bridges of the station. The prestressed concrete bridges carry the platforms with spans of 18, 21 and 18 meters. The platforms for the north–south and underground line are at about 15 m below the ground level. The partly prestressed, very slender massive concrete bridges of the east–west viaduct are at about 10 m above the ground level. To get sunlight to the underground level, the view through the central station from the top level to the bottom platforms is open, without any through floors. For this reason, 23-m-high steel columns carry the massive prestressed east–west concrete bridges. The steel columns are composed of four single tubes each and form a fork-shaped support for the partly prestressed concrete bridges at their tops.

1.2 Monitoring Needs

The steel structure of the glass roof was calculated following the rules of the German national standards DIN 18 800 using partial safety factors according to the modern concept with limit states [1]. During the 1990s, the calculation of the massive concrete bridges followed the rules of the former edition of the German railway standards. The railways still use the concept with allowable stresses and global safety factors. In the level of the supports, a safety factor was applied to compensate for any shortfall in the different safety concepts, the traditional calculation of the concrete superstructure below this level, and the calculation of the glass roof above that followed the new limit states concept. Although additional adapting factors were introduced by the steel specialists at the Technical University Aachen, the Federal supervising authorities for German railways (Eisenbahnbundesamt) required a monitoring system to follow differential displacements between neighboring glass roof supports along the sensitive outer bridges. According to these requirements, the vertical level of the structure must not alter between adjacent glass roof supports by more than 10 mm. A monitoring system should survey the limits of differential vertical displacements. A geometric benchmark system shall be connected to the ends of the monitoring system to have a link between the absolute vertical level and relative displacement data.

2 Monitoring Concept

  1. Top of page
  2. Introduction
  3. Monitoring Concept
  4. Measurement Systems and Advanced Sensors
  5. Results
  6. Conclusions and Outlook
  7. Acknowledgments
  8. References

2.1 State of the Art

Monitoring of critical parameters, mainly referred to as structural health monitoring, originates from the airplane and space industries. Continuous data acquisition of critical parameters allows survey of critical areas during changing loading conditions. On-line data availability gives early warning if the data exceed limits to providers of the systems or to the owners. In the late 1990s, it was quite a new concept to apply these ideas to displacements and strains of structures in civil and infrastructure engineering. Furthermore, appropriate long-term stable sensors were not available for all complicated tasks. Sensor development and data acquisition systems are quite cost intensive. Advanced sensor development, but as simple as possible, makes the idea of continuous survey affordable to their application in civil engineering structures. Finally, on-line monitoring for display of data to researchers and owners of the structure was a completely new and higher level of structural survey [2].

2.2 The Objective of the Monitoring System

A group of scientists at the Federal Institute for Materials Research and Testing, Berlin, BAM, developed a concept for a continuous monitoring system to quickly measure the most relevant data needed for a reliable interpretation of possible changes in the structural condition during construction[2]. The aim was to obtain immediate on-line information about significant differences of displacements and strains in chosen cross sections. The significant period for monitoring was the construction process until the opening of the station in 2006. During the construction process—different load cases from excavation, flooding of the excavated pit, erecting of new structural parts, and dismantling of old structures in the neighborhood—the different load cases cause a continuous change in the structural performance. In some cross sections, the changing loading conditions may cause critical performance scenarios. Therefore, the concrete was cast after the sensor cable tubes were already located in the scaffolding (Figure 3).

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Figure 3. The cable tubes for the sensors were fixed in the structure before the concrete (see arrow).

The following global load cases were expected:

  • loading the steel columns after removing the scaffolding of the concrete bridges;

  • surveying the changes during prestressing process in the middle bridges;

  • unloading the immediate vicinity due to dismantling the old suburban train viaduct;

  • unloading the surrounding by excavating the north–south tunnel;

  • loading the surrounding by flooding the excavation pit with ground water;

  • loading the surrounding by casting foundations for the underground track in the north–south tunnel;

  • unloading the ground beside the viaducts by removing the ground water;

  • completing the track on the bridges and in the underground level;

  • completing the framing of buildings.

The function of the chosen measurement system and its long-term stability are contemporarily verified and validated in laboratory monitoring on beams with comparable loading conditions. The information is made available in real time, using the Internet. The Internet collects data of both the sites, at the station and in the laboratory. The software design was specified and developed for this application at BAM.

2.3 Data Handling and Data Transfer

Both the systems, model beams in the laboratory and the sensors at the station, deliver all data also to the central computer, located at the Federal Institute for materials research and testing. Scheme for data acquisition, preprocessing, and transfer is shown in Figure 4. The fiber-optic sensors use the commercial data acquisition amplification and processing. All the other sensors are connected to an amplifier “centipede” (Hottinger) and have a different time basis. Both the systems are connected to the local computer and after processing to a unified Internet representation. For central data processing and maintenance of the monitoring system, a central network control unit was arranged at BAM in cooperation with the Engineering laboratory. The central network control unit was the local junction box for the model beams, one located in the laboratory and the other outside the building under environmental conditions. For more information about the model beams, see [3].

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Figure 4. Scheme of the data acquisition, preprocessing, transfer via Internet, and accessibility of the webpage to researchers and end users.

2.4 Monitoring System

The continuous survey of vertical movements, strains, inclinations, and temperatures makes it possible to react very fast on early warnings to avoid possible damage. A procedure was proposed to the Federal railway authorities on how to react with corrective decisions and measures in time, i.e., raising or lowering the bridges at supporting points, depending on measurement results. Geodetic measurement of vertical displacements at the supports of the glass roof and at the head of the columns cannot be repeated at sufficiently short intervals owing to the time-consuming procedure and limited accessibility of measurement points [4]. The monitoring system consists of two main elements, installed on both the places, as well at the new main station as in the laboratory beams, to validate the function of the system:

  1. monitoring of the vertical displacement at the supports of the glass roof and on the prestressed middle bridge (Figure 5);

  2. strain measurement in the partial prestressed outer bridges in the structure of the main crossing (Figure 6).

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Figure 5. View of the monitored bridge of the main station during the construction phase. dark: laser displacement sensors; white: hydrostatic leveling system.

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Figure 6. Strain measurement in the partial prestressed bridges and sketch of the measurement system for vertical displacements consisting of laser displacement and hydrostatic leveling components. [Reproduced with permission from Harald Kohlhoff.].

As the Federal railway authority required, a redundant strain measurement system, including interference-free fiber-optic sensors, for the monitoring of the partly prestressed bridges at least during the construction period of about 5 years is needed.

The data were collected together with temperature as the environmental parameter, which has an influence on the system. About 2000 single wires in cables are collected in hollow tubes, hidden in the concrete structure, and lead to junction box in a central room at the station. All components of the equipment, such as the electric distributing switchboard and the main computer for data acquisition, are located in the central unit at the station.

The long-term control of changes in the structure was made possible from the beginning of the construction period in 2002. Initially, data were taken manually, before the communication system started working reliably. The positions of sensors in the partial prestressed middle bridges were already prepared during sheeting of the concrete construction to minimize the risk for the structures during construction and demolishing work in the vicinity of the building.

To restrict the number of sensors at the station, it was decided to monitor only the two outer bridges that have additional static loading from the roof structure. To get as much reliable and redundant information as possible, different types of sensors were installed.

2.5 The Basic Elements and Types of Sensors

The concept of the field test consists of 128 sensors. Table 1 gives an overview on the sensor types, their location, and measurement uncertainty.

Table 1. Sensors, Their Location, and Measurement Uncertainty
Type of sensorNumberLocationMeasurement uncertainty
Strain gauges40Bridges 12 and 15±3 µm m−1
Fiber-optical sensors Bridges 12 and 15 
Strain gauge rosettes16 (+16)Columns under bridges 12 and 15±3 µm m−1
Hydrostatic leveling buoyancy cylinders30 (+4)North and south viaductDistance: approximately 500 m ±0.3 mm
Laser sensors10Bridges 12 and 15Measurement range ±40 mm ±0.2 mm and add. ±0.1 per 10-m beam length
Temperature sensors12North and south viaducts±0.2 K
Inclination sensors10North and south viaductsMeasurement range ±3° 0.03°

To increase the redundancy of the strain measurement data, different sensor types were installed. The concrete strain measurement—only in the partial prestressed bridges—is performed by means of electric strain gauges, fiber-optic sensors, and mechanic contact strain measurement (type Pfender, BAM). Figure 6 shows the cross sections with strain monitoring in the middle and at the supports.

Contact strain measurement delivered absolute elongation (strain) data in the first phase of monitoring. Unfortunately, the measurement points were removed during the following completion works by sandblasting. Figure 7 shows the cross sections with the strain measurement in the prestressed bridges 12 and 15.

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Figure 7. Cross sections with strain measurement points in the prestressed middle bridge and in the upper part of the steel columns. Sensors a–e: fiber-optic sensors and electric strain gauges. [Reproduced with permission from Ref. 5. © IABSE, 2003.].

3 Measurement Systems and Advanced Sensors

  1. Top of page
  2. Introduction
  3. Monitoring Concept
  4. Measurement Systems and Advanced Sensors
  5. Results
  6. Conclusions and Outlook
  7. Acknowledgments
  8. References

3.1 Strain Measurement

Strains are measured in

  • five cross sections of the partly prestressed middle bridges (north and south) to get information about the near-surface strains, nonsymmetric movement, and/or inclination;

  • the upper part of the steel columns to get information about moments and inclinations.

In the outer concrete bridges, in line with the bridges carrying the roof, fiber-optic sensors, electric strain gauges, and a mechanical strain measurement system (type Pfender) were installed. Since concrete may have local inhomogeneity or cracks, a comparison between locally measured strains by means of electric strain gauges with strain measurement on a longer base line is advisable. For this purpose, fiber-optic sensors are used. For comparability, strain gauges and fiber-optical sensors are located in the same slits and have the same gauging axis.

Like all other data, the strains are measured four times a day. For their near-surface position, the influence of temperature changes is expected to be relatively high compared to other influences as, e.g., symmetric traffic load. The system does not measure the strain distribution inside the massive concrete cross section since the number of sensors was limited.

Electric Strain Gauges

Prestressed Concrete Bridges In five cross sections in the middle of the structure and at the supports of the steel columns, strain gauges (TML) are applied in slits. Electric strain gauges are embedded together with the fiber-optic sensors in slits, relatively close to the upper and lower surface in five cross sections of the prestressed bridges crossing the platforms of the north–south track. All slits were closed after all sensors were installed and the function was validated. Temperature influences the strains very much. In few measurement points, temperature sensors are applied together with the strain gauges.

Steel Columns Two ∼25-m high steel columns, each composed of four single columns (see Figure 7), support the prestressed massive concrete bridges. In these cross sections at the supports above the “arms” of the composed steel columns, the maximum strain should occur (Figure 7). The composed steel columns have a hinge bearing on the ground level. Strain rosettes are positioned in the upper part to get information about the loading, inclination, and settlements. For temperature compensation, additional strain sensors were added to each pair of electric strain sensors perpendicular to their axis.

Fiber-Optic Sensors

Fiber-optic sensors have the advantage of not being sensitive to electromagnetic influences, e.g., from high-voltage cables. The applied, commercially available fiber-optic sensors (SOFO-Smartec) with a length of 0.50–3.50 m work on interferometer principle. In a tube two standard optical fibers are placed and, one of them, the sensing fiber, is fixed at defined points and the other, the interference fiber, is loosely placed in the tube. The second fiber is used to compensate for temperature influences. In real time, the measured data are collected, amplified, stored, and preprocessed by calculation included in the software package. The fiber-optic sensors are connected to a demodulator, which is a one-channel device using a multiplexer for multichannel operation. The fiber-optic sensors have their own time base in a separate receiver [4].

3.2 Vertical Displacement Measurement

Introduction

The vertical displacement measurement at the outer bridges 12 and 15 consists of 16 sensors each, in a chain of hydrostatic-leveling sensors in the arched sections and the laser-based vertical measurement above prestressed bridges crossing the north-south track. Figures 5 and 8 show the scheme for the location of the measurement points at the supports of the roof on the north and south bridges.

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Figure 8. Length of the monitored supports of the outer bridges and connections to the geodetical benchmarks. [Reproduced with permission from Harald Kohlhoff.].

Changes in the vertical level between two neighboring supports should not exceed 1 cm. The relative displacement is measured continuously four times a day. In some places, inclinations perpendicular to the axle of the bridges and the temperature are measured. Geometrical imperfections resulting from displacements and inclinations cause additional loadings in the bridge structures. If the limit value would be attained, then a vertical lifting or lowering of the bridges is needed using the vertical adjustability mechanism.

In the middle part of the bridges between the two roofs, the architects denied installation of the relative huge hydrostatic cylinders for aesthetical reasons. Both the hydrostatic leveling system and the laser-based optical system are installed at the outer bridges and appear in the Internet presentation as one chain.

Laser-Optic Leveling System

On this place, the BAM combines the hydrostatic leveling with an elegant small laser-based sensor system. One laser source emits a vertical laser in the middle of the bridge. Prisms divide and switch the vertical laser beam into horizontal direction to the left and right side along the bridge axis. The widespread lasers meet laterally displaced photodiode chains. Each chain consists of 64 photodiodes; the activated diode is a measure for vertical displacement (Figure 9).

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Figure 9. Laser measurement system upgraded by Knapp and Kohlhoff. [Reproduced with permission from Harald Kohlhoff.].

Hydrostatic Leveling System

The traditional hydrostatic leveling was improved to obtain a long-term stable chain of sensors to reduce creep and drift of the force transducer. The principle of measuring the displacement of a buoyancy cylinder has been selected for avoiding measurement errors due to influences by partial heating of the sensors, e.g., if exposed to direct sunlight. Raising the liquid level by pumping liquid into the system permits the buoyancy body to separate from the force transducer, as well as checking the operation of the hydraulic system (Figure 10) [6]. This allows to obtain a zero-value in system maintenance. The hydrostatic leveling system automatically records the level of the liquid as a measure about relative vertical displacements. The data is measured as load cell. A benchmark point is connected to the hydrostatic leveling system within the next weeks. The connection to this “fix point” makes it possible to connect the relative settlements with a geodetic measurement, performed on behalf of the German railways (DB AG). The principle of the hydrostatic leveling system was improved to obtain long-term stability with regard to reducing creep and drift of the force transducer.

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Figure 10. Hydrostatic leveling system type Kohlhoff (patent [7]). [Reproduced with permission from Ref. 7.].

3.3 Maintenance and Long-Term Stability

The chains of hydrostatic sensors on both the bridges have been collecting data since May 2002. During that summer, the data was transferred periodically. Sensors used for construction monitoring must be robust. Construction work and finishing may damage sensors or cables. The ongoing construction work prevented the connection of the measurement points to fixed points. The continuous transfer of data for online presentation on the internet website was available from October 2002 (Figure 11).

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Figure 11. Website with the position of the sensors in the north bridge (bridge number 12).

During the 5 years of monitoring, the combined system for the vertical displacement, consisting of the hydrostatic leveling and the laser-based leveling system, was maintained several times. The advanced hydrostatic leveling allows to validate the measured data by pumping the fuel into an external pot. This procedure unloads the load cells, after which a real zero-value can be read. Alternatively, mechanical measurement of the fuel level is possible to compare the on-line with real data. In case of dysfunction, some of the sensors can be replaced by new ones. Others may be in non-accessible positions. During harsh conditions of construction processes, accidents can lead to disturbance of the measurement chain. Since the access is limited in the station that is in service, maintenance is almost impossible.

4 Results

  1. Top of page
  2. Introduction
  3. Monitoring Concept
  4. Measurement Systems and Advanced Sensors
  5. Results
  6. Conclusions and Outlook
  7. Acknowledgments
  8. References

The monitoring system was installed before the beginning of the extreme loading conditions, during construction activities in the vicinity of the east–west viaduct.

In 2003, the trains were shifted from the old track to the new track through the new station. Before the first train was shifted, the German Railways made a proof load test, with measurements of displacements. It was possible to increase the data acquisition rate for the BAM monitoring system from only four data per measurement point to about 80 Hz to get information about the strains under traffic. Fiber-optical sensors and the leveling system were not used for these measurements, since the configuration for these systems was appropriate for long-term measurements with only a few data collected per day.

4.1 Relative Settlements at the Roof Supports

The main objective of the monitoring system was controlling the differences between the displacement of neighboring roof supports. During demolition of the old station (Figure 12), excavation of the north–south tunnel, and flooding of the excavation pit (Figure 13), the east–west viaducts carrying the glass roof were exposed to load differences. Figure 14 shows the differential in settlements and heaving with relative displacements during the loading and unloading phases in the vicinity of the station from May 2002 to July 2003. The positive result was, that over the whole construction, required displacement limits were not exceeded, not even in the year 2003, during the hectic period of dismantling of the old structure and excavating the north-south tunnel (Figure 13).

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Figure 12. Load case: demolition of the old station.

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Figure 13. Load case: flooding of the excavated pit with ground water.

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Figure 14. Settlements and heaves during demolition of the old station, excavation of the north–south train line, and flooding of the excavated pit.

Figure 15 shows the differences in relative vertical displacements between neighboring roof supports obtained from the chain of the hydrostatic leveling and laser-optic system, for 1 month, as an example. For this purpose, the relative displacement is compared to a mean value of all sensors, including both the leveling systems, by using data displayed from the website.

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Figure 15. Example for relative displacements for 1 month in March 7, 2003 by means of the hydrostatic and laser measurement at the south bridge.

4.2 Strain Measurement

The monitoring of strains is of special interest in partially prestressed bridges. As in the measurement of relative displacements, the measured data have been reliably collected, amplified, stored, and preprocessed by calculation in real time for 5 years. Although both the systems, the electric strain gauges and the fiber-optic sensors, have a different time basis, both the data sets are given in a unified Internet representation.

The analysis of data showed, e.g., in the first year a maximum strain difference of 585 µm. For a maximum temperature difference of 40 K, it results in a mean value of about 10 µm m−1 K−1 for the gradient.

The measured values are influenced by many factors, such as shrinking, creeping, nonlinear temperature distribution in the massive concrete cross section, and the fact that a real zero-value cannot be measured again.

The measurement began immediately after the structure was erected, partially prestressed, and the shrinkage was already in process. These values were estimated from calculation and from evaluation of the model beams. Figure 16 shows the course of strains measured with fiber-optic sensors in four points of the prestressed bridge no. 15 for 5 years. The curves with the daily midnight temperatures in three points of the same bridge show that the influence of temperature on the main strain is dominant (see Figure 17). Also it shows, of course, that the temperature and, as a result, also the strains did not reach the negative temperatures, as before. Two reasons are responsible for this result: the warm winter 2006/2007 and the finalizing of the roof. In 2006, the middle roof was built in such a way that the bridges are now located inside and are not exposed to harsh environmental conditions anymore. The strains are lower, which means the structure is safer.

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Figure 16. Continuous strain data measured with fiber-optical sensors for 5 years in the partial prestressed bridges. The compression during winter was lower since 2006 because the middle roof was closed and the temperature influence was reduced.

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Figure 17. Continuous temperature measurement for 5 years (only midnight values).

4.3 Long-Term Stability and Maintenance

Continuous control of the stable function of all sensors and the load cells is needed. During first year in service, only three sensors failed (less than 3%), a temperature sensor and two electric strain gauges. Since all slits with the strain sensors are closed, no access is possible anymore.

It can always happen during construction processes that scaffoldings destroy sensors or application of secondary elements hit a cable, e.g., by drilling. Repair and maintenance of systems of this logistic extend require experienced specialists. That is why the access to all sensors, especially to sensors for vertical displacement, is advisable. Reduced maintenance may affect the long-term stability and service of the monitoring system.

5 Conclusions and Outlook

  1. Top of page
  2. Introduction
  3. Monitoring Concept
  4. Measurement Systems and Advanced Sensors
  5. Results
  6. Conclusions and Outlook
  7. Acknowledgments
  8. References

The presented monitoring system at the Berlin Main station has been reliably working through all construction phases. The system provided continuous on-line data for sensitive parameters of the glass roof. The limits, stated by the railway authorities, as for relative vertical displacements between neighboring glass roof supports, have not been exceeded. The sensors have been working stably for 5 years. The system needs continuous maintenance by experienced specialists.

Measured data are immediately preprocessed and have been presented on line via Internet. Thus, the researchers and the client, the German railways, DB AG, always have the opportunity to identify possible changes of critical parameters at any time.

Acknowledgments

  1. Top of page
  2. Introduction
  3. Monitoring Concept
  4. Measurement Systems and Advanced Sensors
  5. Results
  6. Conclusions and Outlook
  7. Acknowledgments
  8. References

The German railways (DB) were financing this monitoring system. We thank DB for the confidence in the implementation of advanced techniques and new sensor prototypes, which have never been used before. We thank numerous colleagues from the Federal Institute for Materials Research and Testing, who carried out the research and enabled the realization of the project. We acknowledge especially Klaus Brandes and Wolfgang Habel, who developed the idea and concept to continuously monitor the construction process during all phases. Klaus-Dieter Werner designed and realized the software for the on-line data presentation, and Hans-Joachim Peschke cared for the data preprocessing and transfer. Without the upgraded sensors for the widespread multipoint laser measurement with several lateral displaced measurement points from Juergen Knapp and the patented hydrostatic leveling system by Harald Kohlhoff, the data would not have been so convincing. All systems worked reliably and stably. Joachim Niemann made continuous efforts to keep the system running for over more than 5 years.

References

  1. Top of page
  2. Introduction
  3. Monitoring Concept
  4. Measurement Systems and Advanced Sensors
  5. Results
  6. Conclusions and Outlook
  7. Acknowledgments
  8. References
  • 1
    Albrecht G, Klähne T, Stucke W. Aspects of the structural examination of the project Lehrter Bahnhof, Berlin, in German: Aspekte der bautechnischen Prüfung des Bauvorhabens Lehrter Bahnhof, Berlin. Stahlbau 2002 71:Heft 12: S-890S-903.
  • 2
    Knapp J, Brandes K, Werner K -D. Optical monitoring system for settlements and inclinations. Proceedings, IMEKO 2000. Wien, 2000.
  • 3
    Ullner R, Helmerich R, Knapp J. Laboratory model test for monitoring the new main station of Berlin, Lehrter Bahnhof. Proceedings of the 1st International Conference on Reliability and Diagnostics of Transport Structures and Means, ISBN 80 7194-464-5. Pardubice, September 2002.
  • 4
    Habel W, Kohlhoff H, Knapp J, Helmerich R, Hänichen H (DB Projekt Verkehrsbau GmbH Berlin), Inaudi D (Smartec SA, Manno/CH). Monitoring system for long-term evaluation of prestressed railway bridges in the new Lehrter Bahnhof in Berlin. Proceedings of the 3rd World Conference on Structural Control. Como, 7–12 April 2002; Vol. 2 S-713S-719.
  • 5
    Helmerich R, Kohlhoff H, Werner K -D, Niemann J. Structural condition monitoring of a high-speed train station. Keynote presentation at IABSE Conference, ISBN 3-85748-109-9. Antwerp, 2003.
  • 6
    Niemann J, Habel W R, Hille F. Complex monitoring system for long-term evaluation of prestressed bridges in the new Lehrter Bahnhof in Berlin. Proceedings of the 2nd International Conference on Reliability and Diagnostics of Transport Structures and Means, ISBN 80 7194-769-5. Pardubice, July 2005.
  • 7
    Kohlhoff H. Hydrostatic Levelling System, Type BAM, Patent No. 10203231, April 2003.