San José, Costa Rica, since 1956

San José's traffic is killing the planet, but it could be fixed

Traffic congestion in Costa Rica’s capital increases greenhouse gas emissions by up to 30 percent and fuel costs by up to 25 percent, a study by the University of Costa Rica (UCR) determined.

The average speed at which vehicles circulate in downtown San José is dreadfully slow, especially during rush hours, which directly affects vehicle emissions, the UCR’s Research Program for Sustainable Urban Development (ProDUS) said.

Data indicate that during rush hours, San José vehicles travel at speeds below 15 kilometers per hour during more than half of total travel time.

“Car engines become more inefficient when they are forced to move at slow speeds, as they are designed to operate at 40-50 Km/h on average, not at 10 or 15. […] Intermediate speeds of 40-80 Km/h are when cars are most efficient,” the study said.

San José’s Second Avenue, Paseo Colón, and various stretches of the Circunvalación – a belt route around the center of the capital – have the worst traffic jams on average.

Jonathan Aguero Valverde, one of the study’s researchers, said that by calculating fuel costs the team determined that fuel consumption in traffic jams increases by up to 30 percent.

The study recommended increasing the average speed on Circunvalación to at least 20 km/h in order to significantly reduce emissions.

The areas most affected on that route are from Hatillo-San Sebastián (south), Zapote-Sabanilla (east-northeast) and between Hatillo 8 and Route 27 intersection (west). In those areas, average traffic speed is at its slowest and emissions are higher.

UCR’s study noted that although better infrastructure is needed to improve traffic flow on the Circunvalación, “there are other solutions that are cheaper and easier to implement that would substantially improve traffic flow, such as traffic-light synchronization, changes in lane directions and prohibition of left turns at several intersections.”

The study says that San José’s roadway infrastructure “is 50 years behind, so finishing the construction of the northern stretch of Circunvalación and building bridge underpasses at all intersections of the entire route are crucial.”

ProDUS researchers recommended similar studies for other important roads in the country such as the General Cañas Highway.

Contact L. Arias at

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