Cutting-edge technologies are contributing to the changing infrastructure and safety of bridges & flyovers, as well as a sustainable transport system.
BY Team CW
There are several modern technologies available for bridge construction.
As commuters, many of us rely on bridges & flyovers as part of our day-to-day journey – they are key to our national road infrastructure. Continuing population growth in Indian cities means that good roads and strong bridges & flyovers are essential for the safe transport of both people and cargo.
Specially, in India, it is important that bridges and flyovers are frequently checked and strengthening programmes are undertaken as capacity changes and bridges age. To get accurate information, bridges must be inspected and this can be a dangerous and costly job. This is where technology is proving a game changer. By using innovative assessment tools that can predict the remaining life expectancy of bridges, monitoring has become much more streamlined.
Over the last few years, there has been an advancements in the area of bridge engineering in India with the introduction of limit state design philosophy, new special vehicle loads and fatigue vehicle for bridge design and usage of construction materials with high strength. Considering these developments and giving importance to durability aspects, it is possible to achieve target design life of 100 years for concrete bridges. With increase in span length of the bridges, more number of continuous bridges (three of four span units) is being built during the last two decades which has led to the development of high capacity bridge bearings, POT bearing, POT-PTFE bearing sand spherical bearings. Also, modular expansion joints have replaced the widely used strip seal expansion joints in many bridges.
Technology is proving to be a game changer. By using innovative assessment tools that can predict the remaining life expectancy of bridges, monitoring has become much more streamlined.
In India, infrastructure plays a key role in faster economic growth and alleviation of poverty. Sanjeev Kapoor, country market director, transport, Ramboll, says, “Adequate infrastructure in the form of road and railway transport system, ports, power, airport and their efficient working is needed for integration of the Indian economy with other economies of the world. Therefore, India is rapidly adapting and utilising the key advancements in bridge and flyover engineering.”
The Santacruz Chembur Link Road brought much relief to Mumbai’s citizens.
Some of these include: Upgraded IRC codes which are at par with International codes such as Eurocodes, AASHTO etc.; movement of overweight consignments was included in the design of bridges which was missing earlier; The MoRTH has set up Bridge Monitoring system (BMS) to identify the bridge assets across length and breadth of the country. All key features of bridges and structures, and their conditions are being monitored regularly by field inspection; majority of the long span, important and strategic bridges are being provided with strain gauges and monitoring systems for online monitoring of their health and condition; sea bridges such as MTHL, Bandra-Worli Sea link, elevated roads, airport express metro links, high-speed rail links, aesthetically pleasing footbridges etc. are being planned and implemented in some major cities in India.
MoRTH has taken a stand that all bridges & flyovers must be inspected on a regular basis.
Another company that is moving to advanced bridges is Dilip Buildcon. The company has bagged a contract worth Rs 546 crores from MoRTH (Ministry of Road Transport and Highways). The order is to build a 640m long, eight lane, cable stayed bridge, across the Zuari River in Goa. Devendra Jain, executive director & CEO, Dilip Buildcon, said, “Mr. Devendra Jain, Executive Director & Chief Executive Officer, Dilip Buildcon Ltd. said, “This is our first project in Goa and we hope to complete the project before time. We have joined hands with a Ukrainian-based company, Mostobudivelnyi Zahin (MBZ) with a 70% and 30% stake respectively, to construct the cable bridge. MBZ has wplenteous experience in construction of cable suspension bridges and will be our technical partner for this project.”
There are also some unique concepts hitherto unexplored in India. For instance, fibre-reinforced plastic (FRP) is an alternative to steel and doesn’t corrode even when exposed to harsh environmental conditions. Ashish Kumar, CEO, Arvind Advanced Materials, says, “It is a composite material manufactured by the combination of glass and polyester, with the same mechanical strength as steel but half its weight. FRP’s density is one-fourth that of steel, but its mechanical properties are much better, resulting in superior strength-to-weight ratio. Also, the Indian government is focusing on strengthening the infrastructure near the northern borders and North-East – both these regions are hilly. FRP bridges are an ideal solution for areas like these. Just to give you an estimate, FRP bridges can be installed as quickly as within 12 hours.”
Much displacement of people can happen during construction of bridges & flyovers if passing through dense cities.
FRP bridges could practically last for the longest time as they are completely non-corroding in nature, while wooden, steel bridges typically need refurbishment after 10-15 years. FRP bridges are a superior alternative for regions with difficult terrain, riverine, coastal areas and high seismic zones. They can also be quickly repaired when broken, recycled if required.
Most of the components of FRP bridges such as girders, rebars, decking panels etc. are pre-fabricated. Being 70% lighter than mild steel, it can be easily transported, handled and managed without the support of large cranes. Being lighter helps to reduce the inertia forces in seismic prone regions.
Similarly, Ashoka Buildcon has been constructing bridges and flyovers, not to forget roads & highways, for over three decades now. Satish Parakh, MD, Ashoka Buildcon, says, “Considering that we believe in completing projects on time, or even ahead of time, we have an in-house research department that takes care of the latest technical trends, ensures that we can avail of the best alternative materials, and all the time keeping our focus on sustainable construction practices and sharing them with our partners and sub-contractors so that the project has the same quality throughout.”
One of the biggest challenges when executing a new technology is that there is not a common level of understanding between all parties. Education and adjustment to familiarise all stakeholders with the technology being implemented is highly important. But India is not too far off in considering new technologies for construction of bridges & flyovers.