The highway is a key road, linking Mexico City with Acapulco Port, one of the most frequented destinations for both domestic and international tourists.
According to several media reports, the students are now allowing all cars to pass through Palo Blanco tollbooth for free.
The students are joined by relatives from the 43 youth who have been missing since Friday September 26, when police agents from Iguala, Guerrero, along with unidentified gunmen shot at several buses being used by the students, and kidnapped 43 of them. Six people, including three students and one 15 year old boy were killed that night.
Guerrero authorities have acknowledged that local security agencies are infiltrated by organized crime. They suspect the members of the United Warriors gang, along with at least 23 police agents, who have been arrested, as being behind the forced disappearances of the students.
Meanwhile, the Iguala mayor and the director of public security of the town where the students were kidnapped have fled after local authorities started an investigation against them.
Also on Sunday, authorities announced that at least six clandestine graves had been found in Pueblo Viejo, an area with difficult access with much vegetation.
At least 28 bodies, which are believed to be some of the missing students, have been retrieved. Security agencies said DNA tests are being conducted to determine the identity of the bodies.
The United Nations has referred to the Iguala massacre as one of the most outrageous events in recent Mexican history.