The failure of bridges, specifically pedestrian footbridges in India, has been in the news following the October 30 collapse of the suspension bridge in Gujarat’s Morbi that left at 140 dead.
Other incidents in recent memory are the Mumbai footbridge collapse in March 2019, the Darjeeling bridge collapse in 2011 and the Bhagalpur railway footbridge that collapsed on a running train in 2004.
But this is not a problem specific to India. Similar incidents have taken place recently in other countries too, like pedestrian bridges collapsing in Miami in 2019, at an interstate highway in Washington DC in 2021, the De la Concorde overpass in Quebec 2016 and the Cuernavaca bridge in Mexico in June. The failure of bridges is often attributed to errors by structural engineers and maintenance issues.
However, that is only part of the problem. The safety of bridges depends on three factors: (a) if the construction standards consider peak capacity; (b) if the bridges are built to adhere to those standards; and finally, (c) if the bridges are maintained well.
In India, pedestrian bridges are at great risk of overcrowding during peak hours or festivals. Hence, the standard setting needs to go beyond the conventional capacities and consider the needs of rapidly growing cities.
The problem with safety standards
India has no official inventory of pedestrian footbridges, making it challenging to follow clear maintenance procedures or provide a rapid response after a disaster.
Of the 256 standards published by the Indian Roads Congress, 46 focus on constructing and maintaining road and railway bridges. Of these 46 standards, only one focuses on the “Design of Small Bridges and Culverts”.
Even there, there are specifications only on the footpath width and protective railings on bridges. There are no norms for the performance or maintenance of footbridges, especially common suspension bridges.
A study on “Regulating Infrastructure Development in India” by the National Institute of Public Finance and Policy emphasised that existing regulations for infrastructure safety are highly prescriptive.
This means there are definitive numbers, such as the width and thickness of structures, that are easy to follow and are typically based on past experience. But the prescriptive regime is proving increasingly insufficient as societal and environmental risks become complex.
Modern infrastructure needs performance-based standards such that the final goal is to prevent failure despite the size of the structural components. Pedestrian footbridges must also be assessed and maintained considering the worst case scenarios. These could result from excessive wind, rain, or overcrowding during a festival.
For instance, European Codes for Traffic loads on bridges (EN 1991-2) have a section on footways, cycle tracks, and footbridges. They recommend considering dynamic forces exerted by “pedestrians who can walk, run, jump or dance, wind, vandals, etc”.
Maintaining bridges: Who is responsible?
In India, Central and state governments and district administrations are responsible for the construction and maintenance of road bridges. Pedestrian footbridges, like the one that collapsed in Morbi, are categorised as small- to medium-sized infrastructure that typically services the local community. Smaller bridges like these often struggle with ownership issues and a general lack of funding, especially when maintained by local communities.
Urban local bodies, such as municipal councils and panchayats, are in the best position to maintain footbridges as they know their day-to-day usage and structural concerns. However, not all local bodies are empowered with the correct information or resources to support such a critical task. Moreover, several footbridges were built in pre-independence India and are well past their design age, compounding the challenge of ensuring their structural integrity.
Bridges often cross administrative boundaries, which disperses overall accountability. The Université Libre de Bruxelles with Amsterdam in The Netherlands will investigate 800 bridges within city limits and restore them, as part of the Urbiquay initiative – Urban Bridge and Quay Wall Innovations. Amsterdam, with many inland waterways, had built wooden bridges, several of which are in a state of decay now.
Future-proof India’s bridges
India needs to adopt a systematic but achievable three-step approach at the ground level to start future-proofing its bridges. The first is to create a state or district-level asset register of footbridges, including details such as the age, material, structure type, and usage intensity. The second would be to develop simplified guidelines for inspecting pedestrian footbridges, including condition assessment, monitoring, and testing.
A consortium of national and state disaster management authorities as well as leading Indian technical institutes could develop capacities at the district and municipal levels to periodically assess the capacity and condition of local footbridges.
A third important policy step would be to create national-level forward-looking structural safety standards that can accommodate rare surge events such as festivals.
In addition, bridges must be designed to be “safe to fail” to minimise damage to the lives and livelihoods that depend on them, even if they partially or completely fail. Inadequate standards and lack of maintenance of footbridges are a challenge worldwide. However, such measures would set the groundwork for an effective standard-setting and maintenance protocol for footbridges that must carry the load of future urbanisation.
Supriya Krishnan is a PhD Candidate at the Resilience Lab TU Delft in The Netherlands.