PRESS RELEASE

OSMOS GROUP and KISR implement an innovative solution for structural health monitoring and weigh-in-motion on PART’s Cairo Bridge in Kuwait

The Kuwait Public Authority for Roads & Transportation (PART) is conducting an important construction project on a Bridge supporting the Istiqlal Street over the Cairo Street in the city of Hawally.

These works consist in excavating two underpasses below the bridge, 10 meters below the original level, constructing retaining walls on both sides and near the bridge piles, reinforcing the piles with a structural support system, raising temporarily the deck of the bridge and replacing its bearing devices.

The bridge is 74 m long, on 2 spans. The deck is composed of Post-tension concrete box girders. It is part of one of the main traffic axes in the State of Kuwait, and must remain open at all times, in spite of the invasive nature of the works around.

PART has decided to implement a Structural Health Monitoring (SHM) system on this bridge in order to confirm that the structure of the bridge will not be affected by the construction works and to keep the bridge open to traffic with full safety for the users.

PART has entrusted the Kuwait Institute for Scientific Research (KISR) and OSMOS Group to perform the SHM of this bridge during the construction works.

The project is an integral part of an Agreement signed in 2019 between OSMOS and KISR for the collaborative research entitled “Real Time Structural Monitoring and Infrastructure”. Dr Jafarali Parol is the Project leader from KISR and coordinating the collaboration from Kuwait.

KISR and OSMOS have installed a set of 20 sensors called Optical StrandsTM, long-basis optical fiber deformation sensors which already equip hundreds of structures in the world. The Optical Strands measure strain variations on critical parts of the bridge and provide:

  • A confirmation of the correct structural behavior of the bridge
  • An early information in case of behavior modifications
  • An evaluation of the criticality of this modification

The instrumentation is completed by 4 accelerometers, for the vibration analysis of the deck and the determination of its dynamic characteristics.

The measurements are recorded by the sensors, transmitted to Expert Data Acquisition System Monitoring (EDAS) Stations, and from there to the OSMOS Cloud and analyzed by the OSMOS Software suite SAFE Works, permanently and continuously. The different stakeholders of this project (Client, contractor, etc.) are immediately informed in case of structural behavior modifications.

The data also provide a complete information concerning the traffic on the bridge, through the Weigh-In-Motion and Deformations (WiM+DTM) module implemented for this project. The same Optical Strands will also define the Gross Weight and the speed for all notable vehicles passing on the bridge.

The SHM system has been installed in October 2020. Since then, the results have shown that the construction works have not caused any structural damages on the bridge, with records of deformations of small amplitudes only and complete reversibility.

The contractor is able to continue the works without structural hazard, delay, with safety for the bridge users and by keeping the timetable.

 

H.E. Ambassador of France, Mrs. Anne-Claire Legendre

Successful stories of French Technology are not only those of multinational corporations. Smart SMEs such as OSMOS Group have been able to gain a worldwide footprint thanks to innovative solutions. OSMOS Solutions are remarkable because they have a clearly useful interest to public operators.

 

Mr. Patrice Pelletier, Deputy Chief Engineer, OSMOS Group SA

The Bridge 30 project is assuredly challenging, where the client has multiple objectives and responsibilities: Safety for everyone, Adherence to the construction schedule, and Respect of the project costs. OSMOS offers a smart suite of solutions for infrastructure owners and operators to face these challenges with success. Not only state-of-the art technologies are deployed for this project but also our latest series of algorithms to carry massive data analysis and interpretation.”

 

Dr. Hasan Ali Kamal, Member of Municipal Council, Kuwait

KISR and our research group is carrying out an applied research in the state-of-art Structural Health Monitoring (SHM) technology. The method to be implemented in the iconic civil infrastructures in Kuwait and elsewhere in the world. This is a combined technology that uses advancements in sensor technology, artificial intelligence, and IOT to assess structural performance, to ensure structural safety, and to provide maintenance strategies. This project is one of the vital steps to transform the bridges in Kuwait into a “smart bridge” and to reduce the life cycle cost of bridge systems.

 

Dr. Shaikha Al-Sanad, Program Manager, KISR

This collaborative project is the first and necessary step towards smart sustainable cities that use information and communication technology and other means to improve the efficiency of operation, maintenance and related services while ensuring that the needs of the economic and environmental aspects are met. Accordingly, the Structural health monitoring (SHM) has the potential to transform the bridge engineering industry by providing stakeholders with additional information to inform decisions about the design, operation, and management of bridges throughout the structures’ lifespans.

 

General view of the Bridge before the works

 

View of the bridge once the new lanes are excavated

 

Four Optical Strand sensors installed below the bridge deck

 

Example of deformations recorded by Optical Strands after the passage of a heavy truck: Limited strain amplitude and reversibility

 

About OSMOS

OSMOS is a subsidiary of EREN Group, the first group dedicated to the economy of natural resources founded in 2012 by Pâris Mouratoglou and David Corchia.

Established in 2006, OSMOS is a recognized specialist in the field of Structural Health Monitoring (SHM). It offers a wide range of solutions in monitoring structural assets of the building, infrastructure and industrial sectors.

OSMOS designs and manufactures innovative sensor systems based on a unique optical-fiber technology, the Optical Strand®. This technology allows the monitoring, the detection and the measurement of deformations and potential weaknesses of various types of buildings, infrastructures, and industrial equipment. OSMOS also develops with engineers, mathematicians and data scientists its proprietary algorithms for data analysis and interpretation. OSMOS’ suite of software, SAFE Works® and SAFE Analyser®, allow its customers and engineers to visualize, analyze and interpret the deformations of infrastructures. OSMOS latest WiM+DTM and SAFE Traffic® software development combined with the Optical Strands® sensors provide both structural health monitoring of bridges and overpasses and weigh-in-motion (WIM).

OSMOS structural health monitoring solutions have already been implemented with customers of the public and private sectors in more than 20 countries worldwide.

 

Media contact

OSMOS Group SA / Johanna JOUBERTEIX

Tel: +33 (0) 1 71 39 85 15

E-mail: jouberteix@osmos-group.com

The Loire-Atlantique Departmental Council has taken a preventive approach in commissioning OSMOS to check the real-world mechanical behavior of two bridges over the river. The enhanced monitoring of those structures will maintain their service levels and ensure user safety, while awaiting major rehabilitation work.

 

Built in the late 19th century, the Grand Pont de Mauves and Haut Village Bridges are part of a group of four strategic structures that connect the banks of the Loire to the east of Nantes. Periodic detailed inspections identified multiple problems, including signs of progressive corrosion, advanced deterioration of the brick arches under the deck and differential settlement of the supports. That damage was caused by the age of the bridges, their permeability and the intensification of the traffic traveling over them.

To maintain its structures’ level of service while guaranteeing user safety, the Loire-Atlantique Department Council decided to invest several million euros in an enhanced monitoring and specialized maintenance program for its infrastructure. With those renovations in mind, the Civil Engineering Department commissioned OSMOS to monitor the behavior of the Grand Pont de Mauves, while awaiting its restoration as part of a series of rehabilitation and modernization work. The Haut Village Bridge was then monitored to assess the effects of the additional road traffic that would be diverted to it during the work performed on the bridge line at Mauves-sur-Loire. This made it possible to avoid shutting down the Grand Pont de Mauves early, a move that would have been costly and inconvenient for its users.

Monitoring of the Mauves Bridge: Ensuring optimal user safety while keeping the structure under enhanced monitoring, leading up to its restoration

The Grand Pont de Mauves had been covered by enhanced monitoring since 2002, as part of periodic monitoring and inspection procedures. In 2018, after pitting corrosion was observed in a number of floor beams, visual inspections by rappellers were arranged in parallel to the schedule of renovation work to restore the bridge. Before that project was launched, the Loire-Atlantique Departmental Council wanted to have continuous, real-time monitoring while the bridge was still in operation, to prevent its premature closure and to control any structural risks. OSMOS was asked to roll out a monitoring system seven months prior to the start of work on the bridge. The goal was to continuously check its elasticity and displacement, in real time, as well as any day-to-day deformation caused by moving loads.

After a period spent studying the Mauves Bridge’s behavior, OSMOS was able to notify the contracting authority of any significant events indicating a change in its overall stability, particularly as a result of temperature fluctuations and moving loads. On the whole, the structure displayed good stability, with a slight tendency toward tension in Span 11. Most of the dynamic strain generated by road traffic was of a low magnitude and had no harmful effects on the bridge’s mechanical behavior. Only the passage of certain heavy vehicles had an irreversible impact on the framework of the bridge. An analysis of all of the deformation amplitudes associated with moving loads revealed that the strain was substantially higher on one part of the bridge. That area appeared to be more “strained” than the others when heavy vehicles passed over it, as a result of localized deterioration of rigidity.

 

Assessing the effects of the traffic diverted to the Haut Village Bridge: Would the additional moving loads pose a threat to the state of the structure?

In anticipation of the diversion of traffic to the Haut Village Bridge during work on the Mauves Bridge, the Loire-Atlantique Department asked OSMOS to place the structure under continuous monitoring. This was because, despite the renovation work and repairs performed on it in recent years, the Haut Village Bridge’s load-bearing capacity was still limited, due to the aging of its materials and its original design. The contracting authority wanted to understand how the structure would actually behave under the “over-strain” caused by the traffic detour. The monitoring also made it possible to refine the modeling assumptions for the bridge and determine the maximum load it could bear.

The structural deformations demonstrated even amplitudes, consistent between the spans, as well as a good correlation to heat fluctuations. The statistical analysis of dynamic events, shown below, highlights the effects of the lockdown on road traffic, including a decline in the frequency of heavy vehicle crossings. Despite a rise in traffic during the 10 days following May 11, 2020, the date when the lockdown was lifted, it eventually returned to the frequency observed during the lockdown. Out of all of the dynamic events, two unusual crossings were recorded, with effects three times higher than the usual consequences of heavy vehicles on the bridge. After those first six months of monitoring, the structure’s behavior displayed long-term stability and responses that were consistent with its traffic loads, even unusual loads. The following months further enriched this analysis.

 

Placing the Mauves Bridge under enhanced structural monitoring while awaiting its renovation, and the Haut Village Bridge during that work, allowed the administrator to maintain operations with guaranteed user safety. The data obtained from OSMOS’s monitoring and statistical analyses will be extremely useful to the Loire-Atlantique Departmental Council when it comes time to recalculate its structures. That way, the contracting authority will be able to verify that their condition is still in line with the expected level of service. The management of this infrastructure can then be oriented so as to ensure their availability and control their structural integrity over time.

 

Testimonial from Thibaut Pannetier, Head of the Loire-Atlantique Civil Engineering Department

“Under our strategy of monitoring the infrastructure along the Mauves and Thouaré bridge lines, we needed to supplement our inspections with a more comprehensive structural approach. It was difficult to control structural risk through the enhanced monitoring performed on the bridges of Mauves, based solely on corrosion measurements and the losses of material observed during semiannual inspections. In particular, the 19th-century bridge design, in the form of riveted connections between plates and multiple trusses with brick arches, would have been complicated to recalculate or would have required the development of calculation models whose modeling time and methods were not in line with the short-term issues related to keeping crossings safe before shutting down the bridge for work.

That’s why we reached out to OSMOS, after sourcing providers in 2019, to install a solution using Optical Strands that would avoid the need for lengthy, complex calculations and that would provide a continuous, quantitative observational approach. It was vital for us to make sure of the bridge’s structural elasticity. Otherwise, we would have had to make the call to shut it down, in a geographic area with relatively few crossing points, making detours very costly for both users and local businesses.

In parallel, the instrumentation installed on the Haut Village Bridge for the same reasons allowed us to make sure it would continue to function correctly when traffic was diverted during work on the bridges in Mauves.

The assistance provided by OSMOS easily satisfied our needs. The team understood our approaches and our constraints, so they were able to recommend instrumentation capable of controlling the risks to people and property. Their responsiveness when rolling out the solution and setting up the support engineering was effective, making this collaboration an experience worth reproducing for contracting authorities managing an infrastructure of complex, aging bridges along strategic roadways. This successful experience is undoubtedly the start of a new orientation for instrumentation strategies, as a complement to periodic inspections and ad hoc assessments.

Finally, the instrumentation on the Haut Village Bridge also allowed the Civil Engineering Department to finalize its calculation model through various iterations, by comparing the digital results with the actual displacement measurements.”

Extending over a length of 7.2 miles (11.6 km), the Mont Blanc Tunnel is a strategic feat of engineering that offers fast travel between France and Italy. It is a major trade route that supports the local and inter-regional economy. In fact, substantial traffic travels along it daily, contributing to its wear and tear. The tunnel is operated by a Franco-Italian organization, the GEIE-TMB (Mont Blanc Tunnel European Economic Interest Group). The company is responsible for the tunnel’s structural monitoring and maintenance, as well as traffic safety and management.

Today, the Mont Blanc Tunnel is a model in terms of safety, particularly with regard to structural aspects. 117 LIRIS Optical Strands installed under the surface of the road provide for its continuous monitoring. The tunnel’s instrumentation is designed to track and analyze its mechanical behavior, particularly as a result of road traffic, and its evolution over time.

Static and dynamic measurements for a dual analysis of tunnel slab behavior

An average of 1,721 heavy vehicles pass through the tunnel, each and every day. Those crossings are dynamic stresses, of varying intensity, that contribute to the structure’s aging. The OSMOS monitoring system measures the effects of those events, which represent not only loads that cause stress to the structure, but also the associated strains on the material. Consequently, the slabs supporting the tunnel’s traffic lanes were equipped with LIRIS Optical Strands.

Over and above dynamic measurements, static analyses are an important part of this monitoring project. They involve measurements taken once an hour, to reveal slow-moving changes to the structure. Because the temperature is taken at the same time, these data can be used to study the structure’s response to fluctuations in heat. Then, OSMOS corrects for the effects of temperature, in order to identify any gradual trends caused by the aging of the structure.

As a result, the objective of the installed monitoring system, approved by the tunnel’s safety committee, consists of studying the mechanical behavior of the concerned slabs, by measuring deformation due to the bowing of the slabs’ undersides, owing to their own weight (static data) and/or to traffic loads (dynamic data).

The combination of these two types of analyses – static and dynamic – allows OSMOS to periodically calculate and assign a stability index to each sensor, as well as to the structure as a whole. The assigned score provides concrete, relevant information to the client, which can then review the structure’s state of health and any changes in its assessment over time.


Overview of the scores assigned to all of the sensors for the latest period (October 2019 to January 2020)

A preventative approach for optimized structural management

The Mont Blanc Tunnel monitoring project is, first and foremost, a preventive one. The goal is to anticipate any structural risks and adapt the level of service, if necessary. In some instances, notable changes to the structure’s behavior may lead to the implementation of protective measures or reinforcement work. By taking a proactive approach, the managers of the Mont Blanc Tunnel have secured the structure and were able to institute an optimized maintenance policy to keep it in a good state of health.

Overall, the structural behavior of the Mont Blanc Tunnel is very stable. Only one of the sensor locations has been characterized as “sensitive,” with significant changes in tension between October 2019 and January 2020. The reason for this abnormal measurement has been identified: a sliver of the reinforcing concrete cover had become detached in a ventilation shaft, causing the tensioning of the Optical Strand installed under the roadway. Since that problem was corrected, the structure’s behavior has stabilized completely and remains under continuous monitoring.

Graph of the deformation curves associated with all of the project’s sensors over the course of the past year (July 2019 to July 2020)

A cement plant’s overhead crane was showing signs of premature fatigue. To curb its accelerated deterioration, reinforcement actions were performed on the equipment. The OSMOS Group was tasked with monitoring changes in the crane’s mechanical behavior, as well as the effects of operating cycles on its condition. By anticipating any deviations, the operator is able to carry out the necessary actions to ensure its structural integrity and personal safety.

Since 2018, the overhead crane has been the subject of structural monitoring, which has detected multiple anomalies, making it possible to anticipate situations before the structure of the equipment and its operation became problematic. The monitoring set-up, comprising eight Optical Strands (long-base extensometers), four short-base extensometers and one temperature sensor, continuously monitors the behavior of the structure. The system is also configured to notify the operator and OSMOS of any anomalies detected in the equipment, in real time.

 

Thanks to OSMOS’s services, the operator can check and preserve its industrial assets

Faced with shrinking budgets and rising performance demands, keeping equipment in good working order and controlling structural risks, while saving money on maintenance, has become a major concern for industrial plant managers. Within this context, structural health monitoring (SHM) tools have emerged as a solution capable of preventing hazardous situations, but also optimizing control and maintenance costs for civil engineering works and industrial equipment.

Whether the need relates to production line supports, intra- or inter-unit structures, storage facilities, or factories or other industrial buildings, OSMOS solutions contribute real added value to structural monitoring policies. By combining monitoring and behavioral engineering, a structure’s exact state of health can now be determined, namely including any emerging problems and their evolution over time, and the impact of operations on its behavior can also be tracked. Over time, continuous, real-time monitoring makes it possible to adapt the usage and optimize the maintenance of structures based on their health, control personal and property safety, and extend the lifespans of industrial facilities.

 

More than satisfactory results have prevented critical situations and saved money on maintenance

By placing the overhead crane under continuous monitoring, for a variety of criteria (such as strain cycle counts, vibration frequency and intensity, and static measurements), OSMOS has been able to assess how the structure responds to its operating cycles. After the first analyses, alert thresholds were defined for reporting any noteworthy changes in mechanical behavior. With this ability to be notified instantaneously of any anomalies detected in the structure, the cement plant’s operator is able to guarantee maximum safety for the teams working on site.

In particular, an analysis of deformation cycles identified the appearance of faults in bolted connections, on multiple occasions. The above graph depicts one of the breaks in a single bolt in one of those connections, which occurred on February 16, 2019 (shown in red), and which was foreseen, despite the fact that the bolt had simply come loose, with no visually apparent problems. Once the repair was performed on February 28, 2019, OSMOS’s teams observed an immediate effect on the data, which returned to normal. The discovery of defects in the connections has prevented critical situations that would have led to shutdowns of operations and had serious consequences on employee safety.

Thanks to the monitoring provided by OSMOS, the plant’s operator has an accurate view of the overhead crane’s state of health and its evolution over time. By identifying weaknesses in the equipment, the operator was able to define a new, tailored maintenance schedule and review its priorities, in order to significantly reduce the cost of upkeep. Since June 2020, fewer stresses have observed on the overhead crane. This phenomenon is a direct result of the maintenance actions performed on the equipment and of the optimization of its use.

Installation of Optical Strands and inclinometers on the flying buttresses © OSMOS Group SA

 

OSMOS Group, which monitors many historic monuments, was contacted by ACMH, responsible for the project’s management, and DRAC Ile-de-France, the contracting authority up until the creation of EPRNDP (the public establishment for the conservation and restoration of Notre-Dame Cathedral) on December 1, 2019. They asked OSMOS for its expertise on changes in the structure of the damaged cathedral. Multiple solutions, based on a customized system of more than 140 sensors and mathematical data processing, were implemented for the continuous, real-time monitoring of the building’s sensitive areas. Looking ahead to the cathedral’s restoration phase, OSMOS’s analyses aim to provide advanced technical support to ACMH and the public establishment (now the contracting authority).

 

On Monday, April 15, 2019, a fire ravaged Notre-Dame Cathedral in Paris, destroying the roof, the framework, the spire and a portion of the vaulting, in particular. Since then, there has been some doubt as to the stability of the building, which was strongly affected by the incident. Within this context of pressing urgency, OSMOS was tasked with placing the weakened parts of the cathedral under continuous monitoring, just one week after the disaster.

 

Tailored solutions to control structural risks and ensure optimal safety for the project to secure and strengthen Notre-Dame

The OSMOS team had to be responsive and react to the various challenges at hand. In consultation with the contracting authority, multiple OSMOS monitoring systems were defined, based on the client’s questions about the movement of the most sensitive structures (vaulting, flying buttresses, gutter walls and damaged scaffolding). Automated alert systems were also set up to notify the teams working on the site, as well as project management, in the event of the structure’s abnormal behavior. The rollout of OSMOS’s systems secured the worksite and made it possible for the teams to safely launch the building’s reinforcement phase.

OSMOS’s model is based on mastery of the entire value chain, from the identification of needs to data analysis and assessment assistance. In the case of the project to secure Notre-Dame Cathedral, the combination of these different skill sets made it possible to offer a service that was fully in line with the challenges. As a result, the project provided an opportunity to activate all of the different disciplines at OSMOS: from the R&D Department to the Installation Department, by way of the team of engineers who specialize in structural mechanics, but also the Science Department, which is dedicated to the creation of data processing algorithms. To offer the best possible support to the client and expand the teams’ availability, a number of extraordinary measures were also taken, namely including the establishment of on-call duty and on-site watch shifts.

As the project went on, the instrumentation increased in number. OSMOS’s actions on Notre-Dame are ongoing, and the company is also participating in an important stage: monitoring during the disassembly of the damaged scaffolding. Its role consists of monitoring the monument’s stability in real time and verifying the new load distribution across the structures in place. Just as with the sensitive parts of the cathedral, a system of automated alerts was paired with the monitoring set-up installed on the scaffolding. Any significant movement of the metalwork is reported to the on-site teams, project management and OSMOS’s engineers, so as to ensure maximum worker safety before and during the disassembly operations.

 

From project safety to assessments: When SHM assists a contracting authority with the preservation of ancient heritage

Since August 2020, there has been a gradual shift from the building safety phase toward an assessment phase. The accumulation of data and their processing by dedicated analytical tools have already yielded relevant information about the cathedral’s residual mechanical behavior. The contracting authority and project manager will use those analyses to plan ahead for the restoration of Notre-Dame.

Along those same lines, OSMOS is preparing to implement a new engineering service, involving analyses of the vibrational behavior of the cathedral’s structure after undergoing repeated external strains, including wind and road traffic, but also the ringing of the bells. These assessments will require a specific vibration analysis methodology and the use of a dedicated mathematical algorithm, developed by OSMOS’s Science Department and proven through other applications, namely on high-rise buildings in seismic zones. Equipping Notre-Dame’s belfries and nave with further instrumentation will enable the identification of their specific modes and frequencies of vibration, with the end goal of re-creating the structure’s overall modal deformation. In other words, this will entail characterizing the cathedral’s mechanical behavior when subjected to vibrations. This new stage in the project is a step forward for research into the structural mechanics of ancient heritage sites.

The data and the analytical results will provide a precious history of the state of the building and the progress made on the cathedral’s reconstruction. To ensure this in-depth knowledge of the building is passed on to future generations, OSMOS is sharing all of its project data, analyses, photos and documents with the CNRS (French National Center for Scientific Research). It is a great source of satisfaction to the company to see its efforts put to work in service of research and used as a historical record of Notre-Dame’s restoration project.

“Some 25,000 bridges are in poor structural condition and pose safety and availability issues for users”

Bridge safety: Avoiding tragedy
Sénat information report no.609 on behalf of the sustainable development and regional development commission
Lodged on 26 June 2019

The most serious structural risks are not always visible. Visual inspections of bridges can only periodically report on visible issues in order to classify the structures according to quality standards (IQOA, VSC, etc.). Given the general ageing of infrastructure, including bridges, managers of those structures need a tool that gives them a clear view of their structure’s health. Our teams have created the OSMOS Weigh-in-Motion + Deformation (WiM+D®), a unique automated system combining weigh-in-motion techniques with an analysis of structural deformations. This new tool describes the loads passing over the structure and quantifies the exact operational impact on its structural condition.

Thanks to OSMOS WiM+D®, managers of structures can schedule appropriate maintenance programmes, spread out long-term maintenance costs and extend the lifespan of their bridges while ensuring the safety of users.

The OSMOS WiM+D® module lets you go beyond standard weigh-in-motion methods which are costly and restrictive in terms of installation. Simply by installing a few non-intrusive optical strands in the most serious deformation areas under the structure’s deck, we can count and weigh heavy vehicles and assess the exact impact of their crossing on the structure’s mechanical operation.

Our accurate data gives you key information about traffic over your structure, including speed and direction of crossing for each lorry, total weight and distribution of weight by axle, length and the maximum resulting strain on the structure. Heavy vehicles are automatically classified by weight and by direction of crossing. This information can then be viewed via the online interface: SAFE WorksTM. Optional video-surveillance cameras can also be installed at each site and linked to our measurement system. Each truck or exceptional convoy can be identified by its license plate and its timestamped passage. That information is also available online in individual files and is subject to GDPR regulations.

A statistical analysis of these dynamic events enables you to assess the structure’s operational rate and verify the deck's mechanical behaviour under moving loads: actual level of deformation, continuity, height of neutral axis, blockages on supports, etc.

Thanks to the OSMOS WiM+D®, you can track your bridge’s health in real time and understand the exact impact of traffic on its mechanical behaviour. This enables you to plan suitable maintenance, adapt the bridge’s service level if required, and prolong its lifespan.

OSMOS WiM+D® application: Example of monitoring a high traffic motorway bridge, with vehicle weight estimation and analysis of exceptional convoy impact

OSMOS was contacted by a European leader in toll road construction and management. The assignment: to monitor the behaviour of a motorway bridge in a setting that generates high traffic. The structure sits above another motorway and a railway, and is frequently used by heavy vehicles, including exceptional convoys. It is therefore important to check the impact of their crossings on the bridge’s condition.

In order to calibrate the OSMOS WiM+D® system to the structure’s response to that traffic, it was necessary to firstly perform load tests. This stage helped identify the dynamic signatures associated with various test loads and check the deck’s normal behaviour when vehicles cross it.

Following the load test, continuous structure monitoring was implemented in order to analyse and track changes in its mechanical behaviour due to internal and external stresses. By analysing those static data, we could study the gradual changes in the structure’s behaviours, including due to temperature variations and its natural ageing. The structure’s actual operating conditions were verified through dynamic data analysis.

Thanks to the OSMOS WiM+D®, the motorway bridge manager can now check the traffic at any time. By monitoring the bridge, several exceptional convoys over the authorised weight limit were detected and recorded. Those vehicles were subsequently identified using video-surveillance cameras linked to the monitoring system. The performed tests, continuous monitoring and information available on the SAFE WorksTM interface enabled the manager to assess the structure’s actual condition, plan remedial work to be undertaken and prevent costly, restrictive closures.

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