In Mumbai, honking past 85 decibels triggered a longer red light—turning impatience into delay, and silence into speed.
Urban noise pollution–although often overlooked—is a silent threat. Excessive honking in congested cities like Mumbai can reach over 100 decibels, well above the WHO’s safe threshold of 85 dB.
Prolonged exposure contributes to stress, cardiovascular strain, hearing loss, and a lower quality of life—particularly for children, the elderly, and shift workers living near busy intersections.
Yet honking persists due to impatience, social norms, and the illusion of control at red lights. Traditional fines don’t scale, and awareness campaigns rarely shift deep-seated habits.
To reshape this noisy norm, Mumbai Traffic Police, in collaboration with FCB Interface, launched a pilot campaign in late 2019 called the „Punishing Signal.“ At five busy intersections—including CSMT and Marine Drive—traffic lights were fitted with decibel meters and LED displays. If honking exceeded 85 decibels, the traffic light’s countdown timer reset, extending the red light duration.
The display delivered a cheeky but clear message: “Honk More, Wait More.”
This intervention flipped the script. Honking—usually seen as a way to assert urgency—suddenly became counterproductive. The campaign applied negative reinforcement, where the removal of an unpleasant experience (waiting) depended on a desired behaviour (staying quiet). Rather than moralising, the nudge aligned with drivers’ real-time emotions—turning impatience into a self-imposed delay.
The results
By turning honking into a self-imposed penalty, Mumbai reframed impatience as an incentive to stay quiet—reducing noise pollution by nearly a third. The campaign’s traction and acclaim hint at its potential to influence public norms in other cities.
Do you know of any clever nudges that help cut noise pollution in cities?
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From Laura Sommer PhD from the Green Nudges Consulting team. This edition explores how urban frustration was turned into a force for collective calm by Mumbai Traffic Police and FCB Interface.
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