The national road agency said contractors will begin replacing the concrete with asphalt on Ruta 32 north of San José Wednesday.
This is a 2.6 billion colon ($5.2 million) job that will take three months. The work area is from the heavily traveled intersection near the offices of La República, the financial newspaper, to the bridge over the Río Virilla.
The Ministerio de Obras Públicas y Transportes and its Consejo Nacional de Vialidad are encouraging motorists to use alternate routes.
The job will be in six stages and covers more than five kilometers. The four lanes of the highway are involved.
Some 60,000 vehicles a day travel this stretch, and the ministry said that workmen will be on the job 24 hours a day.
For most of the time only one lane will be open in each direction.
This is the major route from San José to points north and to Limón and the Caribbean coast.