Tuesday's resignation toppled the coalition government of Saad al-Hariri, who said he had hit a "dead end" in trying to resolve the crisis unleashed by the huge protests against the ruling elite.
Early on Wednesday, troops cleared one major route north of Beirut after briefly scuffling with demonstrators. A group of soldiers tried to pick up a vehicle blocking the highway before it drove off, al-Jadeed television images showed.
The Ring Bridge in the center of the capital opened after negotiations with some protesters who did not want to leave, saying they wanted more of the authorities to resign. Many protesters stayed on, but did not block the whole road.
In a statement, the army command said people had a right to protest, but that applied "in public squares only."