Scientist’s vs NCRPO’s crowd estimate of Pasay grand rally

April 25, 2022 - 9:13 PM
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Pasay City grand rally Robredo
The crowd of supporters of Vice President Leni Robredo filled the stretch of Diosdado Macapagal Boulevard as well as two other adjacent streets to join a massive street birthday party as part of her presidential campaign on Saturday, April 23, 2022. (Team Leni Robredo)

Geologist Mahar Lagmay worked out his own assessment of the crowd based on Google Maps of a campaign rally he attended in Pasay City last Saturday, April 23.

Lagmay shared on Twitter a screenshot of the stretch of Diosdado Macapagal Boulevard, the venue of the rally to debunk the Metro Manila police’s modest estimate of 100,000.

“Heto ang area ng napuno ng mga tao kahapon sa Pasay. Nandun ako at nakita ko na halos nagkakapalitan na ng mukha ang mga tao,” he tweeted.


In the image, he showed the length of the venue from the entrance/exit areas at the corner of EDSA up until the other end at the corner of J.W. Boulevard.

Google Maps showed that the area of the site is 59,261 km2 and has a perimeter of 3.39 km.

He tweeted this to counter the 100,000 crowd estimate the National Capital Region Police Office had reported to the media.

Lagmay said that given the data on the map, the number of participants should have been higher.

“At nag overflow ang mga tao sa peripheral areas. They stayed up to almost midnight. Malabo na 100,000 lang iyon. It was definitely so much more,” he said.

One user replied to him with links to videos that showed large groups of people crammed in different parts of the road.

Lagmay later shared a drone video that showed the packs of people that covered the entire venue with spillovers from the walkways and streets.

Vice President Leni Robredo celebrated her 57th birthday through a grand people’s rally and street party along this boulevard on Saturday, April 23.

Robredo, her running mate Sen. Kiko Pangilinan, some members of their Senate slate, her three daughters were among the guests of her birthday bash.

The organizers estimated around 412,000 participants at the event.

RELATE: Misleading: Jay Sonza’s photo post about Pasay rally

The NCRPO, on the other hand, announced that there were only between 90,000 and 100,000 attendees.

“Parang inano na namin ‘yung area, ‘yung span ng area na kinoordinate nila parang sinubdivide na natin ‘yan by square meter ‘yung occupied ng tao, tapos we also observe kasi na people go there siguro stay for a while and then they will leave hindi talaga yung consistent na they’re staying there,” Major General Felipe Natividad, regional director ng NCRPO, was quoted in a report as saying.

Importance of crowd estimation

A research guide on crowd counting published on the Library of Congress website stated that the process involved both mental math and estimation.

“Crowd estimates were calculated in a similar manner where mental math and imagination are intertwined to compute the number of attendees. For example, given specific square footage that would encompass a certain amount of people, density, and area are put into consideration in order to determine the numbers of large crowds,” the guide said.

Researched Chris Cocking also wrote on The Conversation that crowd estimation is particularly important to prevent large-scale disasters.

“Being aware of a crowd’s mere physical size at any fixed point is generally of little use on its own. To prevent crowd disasters, it is vital to also consider the dynamic build-up of crowd size as well as what crowd members are actually doing,” Cocking said in the article.

Lagmay is the executive director of Project NOAH or the Nationwide Operational Assessment of Hazards, part of which deals with mapping in order to assist in disaster risk reduction and management.