Residents of the Paquera area of the Nicoya peninsula blocked a key highway early Wednesday and then engaged in a running battle with police.
The Fuerza Pública said that 10 persons had been arrested.
The residents, who are being described as strikers, first blocked one section of Ruta 160 with dirt, rocks and tree trunks and then dumped more trash on a bridge at midday after police cleared the first obstructions.
The Fuerza Pública said that about 200 persons were involved in the protest. Some 60 police officers responded through the day. At least three officers suffered injuries from flying bottles and stones.
Protesters torched the second blockage on a bridge known as La Gallada. Dark, black smoke swirled to the sky. Shortly before 1 p.m. police managed to extinguish the flames and clear the bridge. They said they were concerned that the heat might damage the bridge.
Ruta 160 was the topic of a meeting Monday between residents and road officials. The Ministerio de Obras Públicas y Transportes said in a statement Wednesday that the people were told that preliminary plans exist for improving the highway but that there needs to be more design work.
Karla Prendas Matarrita, a lawmaker with the Partido Liberación Nacional, represents the area. She said Wednesday that the protesters were not satisfied with the presentation by the government.
She pointed out that she had been trying to get information on the project and had to file a Sala IV appeal to get it. An additional Sala IV order told the road agency, the Consejo Nacional de Vialidad, to fix the road, so some asphalt was put down.
The highway now is mostly gravel, and it runs to Playa Naranjo to the north some 24 kilometers, about 15 miles.
The public works ministry sent a backhoe to the protest Wednesday to help clear the debris but warned later in the day that its crews would do nothing as long as the protests continued.
The agency said the blockade was not justified.
The road work is part of a much larger package that is being financed by the Inter-American Development Bank.
Paquera is well-known to tourists because it is the community closest to where the Puntarenas ferry docks.
Lawmaker Prendas said she invited President Luis Guillermo Solís and highway officials to meet with residents of Paquera today.