If you drive down EM Bypass towards Park Street a little after 1pm on Thursday and find traffic already in reverse gear, don’t look at your watch. Blame police instead for turning vital public information into one-way traffic.

The traffic police department on Wednesday announced new one-way timings for traffic on seven thoroughfares in the heart of the city without even a day’s notice. On all these roads , the switch in direction will begin at 1pm from Thursday instead of 2pm, as it has been all these years.

There was no advance information of the changes, though police chief Gautam Mohan Chakrabarti claimed that “some advertisements had been issued through the department of information and culture”. He could not say where and when the advertisements were published. Neither could his deputies, special additional commissioner (traffic) Ranvir Kumar and deputy commissioner (traffic) Manoj Verma.

“If the commissioner has said so, then the advertisements must have appeared, but I can’t recall where,” Verma said.

It is the norm for announcements about changes in traffic rules to be made well in advance, usually through the media. But even on Wednesday, the police seemed reluctant to disclose their plans about changes that were to take effect the very next day.

On previous occasions when traffic regulations changed, the deputy commissioner (traffic) organised news conferences to make the announcements.

The additional commissioner of police, K. Hari Rajan, asked reporters to contact the deputy commissioner (traffic) on being asked for details about the changes being put in place — the first time since 1988, when two-way traffic on Shakespeare Sarani and Park Street was banned.

Chakrabarti only said that the police would do their best to overcome the “hiccups” caused by the sudden change in timings. “We are doing this on an experimental basis. Let’s see how it works out.”

Kumar said the changes were made after a study. “We observed that the pressure of south-bound traffic mounts from 12.30 in the afternoon. So, we decided to advance the reverse flow by an hour to smoothen traffic in the southward direction.”

He quoted traffic officers as saying that the number of vehicles heading south down Cathedral Road increases after noon, but with the road restricted for north-bound vehicles till 2pm, most have to take a winding way out.

“Given the volume of traffic along JL Nehru Road that heads south during this time of the day, it made no sense to wait till 2pm to bring about the switch. With the timing advanced to 1pm, more vehicles will be able to disperse from JL Nehru Road towards the east and south through Park Street or Shakespeare Sarani,” another officer said.

He said the “experiment” was being implemented now because most schools had closed for summer holidays.