Outside Santa Cruz, Bolivia's most populous city, the highway starts to resemble a parking lot with dozens of cargo-laden trucks stopped in a long line as exhausted-looking drivers wait by the side of the road. Wet clothing hangs from the windows of some trucks.
The vehicles are blocked by large mounds of sand piled on the highway as it passes through the town of San Carlos, 68 miles (110 kilometres) from Santa Cruz. No cars or trucks pass the mounds, only motorcycles transporting people.
"This measure is to make the government realise that they can't live without Santa Cruz," said Micol Paz, a 32-year-old activist with Santa Cruz Gov Luis Fernando Camacho's Creemos political party.
The detention on terrorism charges in December of Camacho, the country's most prominent opposition leader, sparked a series of protests in this eastern region that is Bolivia's economic engine and farming hub. Road blockades demanding his release, like the one in San Carlos, have thrown the distribution chain into chaos, caused prices to surge and worsened tensions between the leftist government in the capital of La Paz and right-wing opposition based in Santa Cruz.