India’s Falling Bridges: Maintenance holds key to long life

There has been a rise in the number of failures occurring in bridges and other infrastructures in India in recent years. Most of these structures are designed for a life of 75 to 100 years.

However, recent failures have occurred on structures much below their lifespan. Proper maintenance of the structures can increase their service life. On the other hand, neglect of proper maintenance can lead to non-functionality of components or failures much earlier.

The most commonly used materials in the construction of bridges are concrete and steel. Concrete, being a material made by men at the site of construction (be it in situ or RMC), is a very durable material, provided proper care is taken to proportion the ingredients.

Else, it suffers from cracking, leading to the ingress of moisture and corrosive salts that cause degradation and reduce the lifespan of the structure. Steel structures generally suffer from degradation due to corrosion. The degradation in concrete or steel is a continuous process that requires monitoring and protection against the deteriorating mechanisms.

A comprehensive set of statutory policies already exists, covering the design, construction, maintenance, and inspection of public structures. The design of structures is done using the standard code of practice, they undergo the independent peer review process, specifications of materials to be used and quality control procedures are well documented. However, when it comes to implementing these in the field, several compromises are made. This, along with the non-compliance with good procedures for inspection and maintenance, makes a structural system highly vulnerable to failure.

There are many loose ends in the construction policies that require tightening to regulate the industry and prevent failures. The site or field engineers responsible for the execution of public projects should have updated knowledge about the best construction practices.

Cement concrete has undergone quite a bit of transformation in the use of many admixtures for achieving high compressive strength, good flowability through congested reinforcement, enhanced durability against cracking among others. The Indian standard codes of practice undergo several revisions.

Though detailed specifications on the use of new materials are spelt out in tender documents, the field engineers are often not aware of the latest innovations. Engineers responsible for executing projects should undergo short and long-term courses on topics related to maintenance, inspection, structural health monitoring, sensor technology, use of drones and AI for visual inspections and predictive analytics, interpretation of test results and digital storage of the maintenance records. Furthermore, the engineers from the client side should be made aware of the thin line separating their responsibilities from those of the contractor regarding details on quality audit. There should be clear guidelines on the responsibilities for every single activity involved in the design, execution and maintenance of infrastructure projects.

The lifecycle maintenance plan must be strictly implemented, including a preventive maintenance schedule right from the beginning of the project. Funds allocated for the maintenance of public infrastructure should be linked to the execution of timely maintenance plans. This will drastically reduce the occurrence of severe damage and reduce repair and rehabilitation costs. Finally, an emergency action plan should be in place as part of preparation for an event that requires the closure of major bridges and flyovers. These should include emergencies not only in the case of severe distress or damage to the structure but also in the case of natural calamities like floods and earthquakes.

(The writer is a professor at the Department of Civil Engineering, Indian Institute of Science, Bengaluru)