The digital solutions used for monitoring bridges have evolved over the past few years. This has made the monitoring and maintenance of bridges more streamlined. Information technology has a key role to play in any bridge asset management system. The building information model (BIM) is increasingly being adopted by the construction industry as it allows for more efficient design, construction and operation of bridges. As per industry reports, the global BIM market is expected to grow at a compound annual growth rate of 24.3 per cent between 2021 and 2026. This demonstrates the increasing importance of BIM in the overall construction industry and its potential benefits in terms of cost and time savings and increased productivity.
BIM
The construction industry is being revolutionised by 3D/4D/5D BIM. A BIM is a digital representation of the physical and functional characteristics of a building or infrastructure. According to a survey by the Construction Industry Council, 97 per cent of construction professionals believe that BIM will be critical to the industry’s future. Further, a study by the National Institute of Standards and Technology found that BIM can lead to a 9.1 per cent reduction in construction costs and a 5.3 per cent reduction in project schedules.
BIM was used during the construction of the Bandra-Worli Sea Link in Mumbai, Maharashtra. This model facilitated the coordination of the bridge’s design and construction, spanning across the Arabian Sea. It helped in identifying and resolving conflicts between different design components before the construction began. The implementation of BIM resulted in a 10 per cent reduction in construction costs and a 15 per cent reduction in project execution time. It also led to a higher quality finished product as potential issues were identified and resolved before the construction phase began. Besides, BIM improved communication and collaboration among various stakeholders, including the design team, contractor and owner.
For the structural designing of the Chenab bridge, which is part of the ambitious Udhampur-Srinagar-Baramulla rail link project (USBRL), Tekla software has been used. Tekla Structures enables the creation of a constructible, parametric model, where each object holds its own data. In addition, all structures, temporary cables and related anchoring towers have been designed using BIM. This data can then be used for fabrication, erection, construction on site and asset management. The use of BIM and Tekla Structures software on the Chenab bridge has made information assessment possible at every stage of the design project while improving efficiency and productivity, and minimising the need for rework. As of February 2023, Indian Railways has started laying tracks as part of the USBRL project on the Chenab bridge. The Chenab bridge, which is claimed to be the world’s highest railway bridge, is expected to accommodate train traffic by early 2024.
Bridge management system
The Ministry of Road Transport and Highways launched the Indian Bridge Management System (IBMS) to collect information about all bridges in the country. The IBMS is a digital system that uses tablet installed with software for data collection on the field. The data is transmitted to the server in the headquarters, and is validated and analysed using the IBMS software. During inventory creation, each bridge is assigned a unique identification number or national identity number, which is based on factors such as the state, regional transport office zone and whether it is located on a national highway, state highway or a district road. Further, the precise location of the bridge in terms of latitude and longitude is gathered using GPS, and it is assigned a bridge location number. Thereafter, information regarding the bridge’s design, materials, type of bridge, loading, traffic lane (length and width of the carriageway) is collected. The bridges are assigned a socio-economic bridge rating number, which determines their significance in terms of their contribution to the daily socio-economic activity in the surrounding area.
Unmanned aerial vehicles/drones
Unmanned aerial vehicles (UAVs)/drones are utilised to generate 3D models of bridges. These drones have the capability to access almost any part of the bridge, including the sides, top and underside, with greater ease and precision than human workers. As a result, they can reach challenging areas, confined spaces and other locations that may pose difficulties for human inspection. By employing UAVs, inspectors can minimise risks, reduce labour requirements and lower costs compared to traditional methods that require specialised equipment and higher levels of expertise.
South Central Railway (SCR) has implemented a range of advanced technologies to improve the inspection and maintenance of bridges, enhancing train safety during different seasons. These include drones, remotely operated submersible vehicles and 3D scanning of some river beds. The UAVs are equipped with high resolution digital cameras, enabling the collection of high resolution images and videos to assess the condition of bridge components over time. Similarly, remote-operated robotic vehicles equipped with high resolution cameras are being used for taking photos and videos of submerged areas using intense light beams for illumination. The vehicles are manually operated on land to direct the vehicle to navigate the remote sections of the bridge’s submerged substructure. Moreover, SCR has installed solar-charged continuous water level monitoring devices at 22 identified bridges. These devices accurately measure water levels up to a range of 30 metres and are designed to work in dust, rain and high pressure conditions.
Other solutions
A new concept called Bridge Information Modelling (BrIM) has emerged, specifically tailored for bridges, and is being applied to various projects worldwide. The adoption of BIM in bridge construction has been limited because instead of vertical architecture, bridges are horizontal structures that typically involve heavy construction assignments. BrIM is a customised version of BIM, which provides a complete representation of the physical and functional characteristics of a bridge asset. Thus, it serves as an information resource during the entire life cycle of the bridge project. The model significantly enhances the quality of design with accurate information, consistent documentation and improved constructability of structures. It enables accurate prefabrication and facilitates just-in-time material deliveries, while also supporting project collaboration across different disciplines.
Parametric modelling is an effective tool for generating a bridge design draft, which in turn facilitates the development of a detailed design. In this method, parameters are set by the engineer and then used for developing a design that meets the specific needs of bridge design. Making changes in the design is also less time-consuming. The parameters can be modified and the software can calculate the impact of the change on the entire model, updating it while ensuring that all the parameters are still satisfied. Further, the need to extensively revise the entire model is eliminated, resulting in significant time savings.
Another solution is the utilisation of reinforced earth technology for abutments as opposed to conventional retaining walls typically constructed to withstand the lateral pressure exerted by an arch or span at the ends of a bridge. Reinforced earth technology offers several advantages, including the ability to be employed in areas where the ground conditions are unsuitable for constructing foundations for retaining walls.
The way ahead
Bridges are one of the most complex structures, which require routine inspection to ensure optimal performance. Therefore, digital technology will continue to be adopted in the design and construction of bridges across the world. While structural health monitoring has become a standard practice in bridge engineering, the implementation of wireless technology will further enhance bridge monitoring capabilities. Furthermore, the integration of a range of innovative technologies such as digital twins, internet of things, machine learning, augmented reality/virtual reality, cloud computing, computer-aided vision systems including image processing and predictive algorithms, and UAVs will enable more frequent inspections and continuous monitoring of bridges.
