By Geeta Pandey
BBC correspondent in Delhi
It is a normal day at the Delhi railway station as tens of thousands of people mill about, waiting to board trains.
Women often have to put up with harassment and lewd remarks
There seems to be a sense of orderliness as passengers wait for a local service to Panipat in the neighbouring state of Haryana.
But as the train pulls into the station, all hell breaks loose.
Uniformed policemen suddenly emerge from the platform, grabbing by the collar and arresting men who have been travelling in carriages reserved for women.
The initiative is part of a drive by the authorities to ensure that men do not stray into women-only compartments.
While all the other carriages are painted green, those reserved for women are red with big letters on the outside saying "mahilayen", which is Hindi for women.
Male passengers in women's carriages have the same excuses
To simplify matters further, there is a picture of a woman at the carriage entrance.
But it is still not enough to stop a lot of men regularly travelling in these coaches.
That is why Northern Railways decided it was time to take action against the male intruders.
"There is a certain section of women passengers who travel alone and we feel they should feel totally secure," said PK Goel, Northern Railways divisional regional manager.
"They should not have to put up with any harassment and lewd remarks," he says.
"Once they enter the railway premises, they should feel totally secure, as if they are in their bedroom."
The women-only drive has been named "Bhairavi" after the feisty Hindu goddess Kali, revered for killing demons.
It began because rail authorities received many complaints from women passengers.
Errant male passengers face fines or even imprisonment
"It is the young men who get into the train with the intention to harass," said Ruchira Chatterjee, assistant security commissioner with the Railway Protection Force, which is spearheading the drive.
"The message we want to give them is that, in local trains in the Delhi division at least, they cannot harass women."
The women passengers are delighted with the initiative.
Varnika is a college student and a regular train user.
"It is much better for us. We are much safer now than ever before," she says.
"It was always very irritating with those men. It was very uncomfortable. If we do not have any men here, we can sit comfortably; we do not have to argue with anyone."
Nevertheless, railway authorities say it is impossible to provide security for the 140 million people who travel by trains in India every day.
So part of Ms Chatterjee's job is to tell women commuters they have to act for themselves.
"People think there should be police protection, but we are trying to motivate them, we are trying to encourage them because that is the only way we can find a permanent solution," she says.
"Women have to come forward and fight for themselves."
Most of the male offenders use the same excuses to explain their presence on women-only carriages.
Some say they boarded the coach because they were accompanying a woman.
Others protest that the train had begun to move and the women's carriage was the nearest one available.
A few flatly deny their offence.
Whatever the circumstances, most are produced before a magistrate and punishments range from a fine to a jail term of up to six months.
The railway authorities say the drive will continue for some time, and that times and routes of the operation will vary so offenders do not think they can get away with it.
From now on, they say, women-only compartments will be just that.