Every night, in slum clusters strung along Delhi’s railway lines, families fall asleep to the same sound: a freight train thundering past at nearly 100 decibels, almost double what India’s Central Pollution Control Board (CPCB) considers safe for a residential area.
For years, this was treated as an unavoidable cost of living close to the tracks.
Now, a growing body of research led by scientists at Delhi Technological University (DTU) is measuring exactly how loud, how frequent, and how disruptive that exposure really is, and what could be done to make life safer for the millions of Indians who live beside railway corridors.
What the numbers reveal
The first clear signal came in 2024, when a DTU team led by Rajeev Kumar Mishra, an associate professor of environmental science and engineering, measured noise at 10 sites near Delhi’s railway stations. Every location exceeded CPCB limits, and disturbed sleep emerged as the most common complaint among residents surveyed.
A follow-up study in 2025, conducted with the CSIR-Central Road Research Institute, went further, monitoring 1,057 train pass-bys across 14 informal settlements. Noise levels breached residential standards at every single site, in some cases by as much as 85%.
Freight trains proved the loudest offenders, averaging around 100 decibels, while diesel locomotives were consistently louder than electric ones.
For context, the World Health Organization’s environmental noise guidelines recommend railway exposure stay below 54 dB during the day and 44 dB at night, slightly stricter than CPCB’s residential limits of 55 dB and 45 dB.
Even by India’s own standards, the DTU data suggests entire neighbourhoods are living with repeated exposure well outside recommended levels, night after night.
What prolonged noise exposure does to the body
Numbers on a decibel meter only tell part of the story. The WHO’s 2018 Environmental Noise Guidelines for Europe links long-term noise exposure to disturbed sleep, cardiovascular and metabolic disease, cognitive impairment in children, and adverse effects on mental health.
Researchers tracked 1,057 train pass-bys across 14 settlements to understand how often communities beside railway tracks face excessive noise. Photograph: (Reddit)
Nocturnal noise, even when it doesn’t fully wake someone, can fragment sleep and trigger stress hormones, the research says. That, in turn, is linked to elevated blood pressure, heart disease, stroke, obesity and diabetes, along with poorer memory, comprehension and critical thinking skills in children.
Noise is only half the story
Homes beside the tracks do not just absorb sound; they absorb ground-borne vibration too.
Mahavir Singh, former chief scientist at CSIR-National Physical Laboratory, points out that India’s current monitoring methods work well for regulatory compliance but do not always capture what residents actually experience: repeated pass-bys, night-time disturbance and years of cumulative exposure.
Brind Kumar of IIT (BHU) similarly notes that while reverberation makes noise dominant at station platforms, vibration can be particularly troubling for homes along open stretches of track. For families living there, the challenge is often not one isolated loud event, but the combined effect of sound, tremors and interrupted sleep.
That distinction could also point India towards better solutions. Instead of simply asking whether a single train meets a decibel standard, monitoring can begin accounting for when trains pass, how often they pass and what residents experience across an entire night.
The tracks can be made quieter
Railway noise is not an unsolvable problem. Indian Railways has already adopted several engineering measures that can reduce it.
K P S Verma, former executive director at the Research Designs and Standards Organisation, points to interventions such as long-welded rails, rail grinding and improved braking materials.
For families living near the tracks, the disturbance is not just sound, but also vibration, shaking homes and interrupting sleep night after night. Photograph: (Shutterstock)
These measures can reduce the noise generated by wheels and brakes, while the continued shift towards quieter electric locomotives could offer another opportunity to lower exposure along busy corridors.
The next step is to extend this thinking beyond the railway system and towards the communities living beside it.
That could mean identifying settlements facing the highest night-time exposure and prioritising them for targeted monitoring. In some locations, planners could explore noise barriers, better building insulation and other protective measures that reduce how much sound enters homes.
The solutions may differ from one railway corridor to another, but the DTU research offers something India has lacked until now: detailed, location-specific evidence that can help direct resources where they are needed most.
Listening to people living beside the tracks
One of the biggest opportunities lies in combining instruments with lived experience.
A decibel meter can record the peak sound of a passing freight train. Residents can explain whether that train woke their children, interrupted a night’s sleep, or shook their homes. Bringing those two forms of evidence together could create a more complete picture of railway noise in India.
Manish Purshottam Manohare of IIT Delhi has cautioned that the absence of long-term Indian health data should not be mistaken for evidence that there is no problem. India can build its own long-term evidence base while acting on prevention, bringing together transportation engineers, environmental health researchers and urban planners.
India has solved parts of the noise problem before
There is reason to believe public attention can lead to practical change.
In Mumbai, environmentalist Sumaira Abdulali’s sustained campaign helped push noise pollution into the public conversation and contributed to the notification of more than 2,000 silence zones.
In Thane, a public interest litigation led the Bombay High Court to order decibel meters at police stations. Delhi too has seen years of campaigning against excessive honking, construction and other forms of urban noise.
Railway noise could now benefit from the same approach: regular community-level assessments, night-time monitoring and planning that accounts for the people living closest to major transport infrastructure.
Turning measurement into meaningful change
The DTU studies have done something important: they have turned an everyday experience into evidence.
For families living beside Delhi’s railway tracks, a passing train is not an abstract environmental issue. But with 1,057 train pass-bys now measured across 14 settlements, researchers have a stronger foundation for asking where interventions can work and who needs them first.
Living beside a railway line does not guarantee ill health. But neither should millions of people be expected to simply accept repeated night-time noise as the price of proximity to public infrastructure.
India already has quieter rail technologies, better maintenance practices and growing environmental monitoring expertise. What is needed now is to bring these tools closer to the communities living beside the tracks.
The trains may not stop running, nor should they. But as India expands and modernises its railways, researchers hope the people living alongside them can finally be part of what that progress is designed to protect.
