Several barricades were installed in front of the Mendiola Peace Arch to block motorists and protesters from entering the area amid the three-day transport strike from Monday, April 29 to Wednesday, May 1.
Transport groups Manibela and Piston organized a nationwide protest caravan to oppose the national government's Public Utility Vehicle Modernization Program (PUVMP).
The road closure in Mendiola is part of the strict security measures implemented by the Manila Police District (MPD).
"Naka-heightened alert po kami until May 1, kaya may barricade at the same time may deployment po kami sa main thoroughfare because of the strike (We are on heightened alert until May 1, that's why there is a barricade and at the same time we have a deployment of personnel on the main thoroughfare because of the strike)," MPD director Brig. Gen. Arnold Thomas Ibay said.
Ibay said that around 300 members of Piston staged a caravan at Liwasang Bonifacio in Ermita at 3 p.m.
Additional policemen and equipment were also dispatched by the Philippine National Police (PNP) at Welcome Rotonda in Quezon City to maintain peace and order in the area.
Police advised motorists of the possibility of heavy traffic along España Boulevard and other major thoroughfares in Manila once the groups of protesters arrive.
Meanwhile, the local government said 48 vehicles were deployed to assist stranded passengers.
Manila Public Information Office head Princess Abante said the transport strike had caused minimal impact on commuters on Monday.
"As per Oplan Libreng Sakay Command Center, no passenger catered this morning," she said.
Manila Mayor Honey Lacuna-Pangan had initially announced the suspension of face-to-face classes on Monday and Tuesday due to the "dangerous" heat index and transport strike.