With huge traffic jams, ramshackle roads and a creaking infrastructure, Sao Paulo faces a daunting challenge as it races to upgrade its overwhelmed transportation system before it hosts the kickoff of the 2014 World Cup.

Brazil's bustling economic capital ranks as the world's seventh most populous metropolitan area, with 20 million people, including 11 million who live within the city limits.

Every day, city buses ferry five million people, the metro system four million while another two million rely on commuter trains, officials say.

The city's transportation nightmare was graphically illustrated on May 23 when a metro strike paralyzed the city, forcing millions to use their cars or the already saturated bus system to get to work.

"As a result, we had 249 kilometers (155 miles) of congested roads and highways, a record morning peak," said Katia de Cassia Jouanini, an agent at the city's traffic control center (CET).

The city's all-time record was set on June 1, 2012 with 295 kilometers of traffic gridlock during evening rush hours.

The CET's control room is a beehive of activity 24 hours a day, with 374 people monitoring road traffic in real time, analyzing feeds from 140 of the 370 cameras installed throughout the city.

Employees man phones to receive information from the public and agents posted at strategic locations before relaying it to firefighters and emergency services in cases of accidents.

Others monitor 868 kilometers of roadways on 25 screens beaming live traffic images while a large map highlights computer graphics of major bottlenecks.

An estimated four million vehicles -- cars, trucks, buses and motorcycles -- clog the city's 17,000 kilometers of roadways on weekdays, officials say.

To make matters worse, hundreds of new cars hit the streets daily as a result of spreading economic prosperity and cheap credit, Jouanini said.

"Every day, we have more cars. It's a challenge to maintain a quality of service with the resources available," Hercules Justino, traffic manager at CET, told AFP. "We need more investment."

With the Rio+20 summit on sustainable development fast approaching, sustainability is the buzzword in Sao Paulo.

At a recent seminar on Brazil's logistics, local business leaders bemoaned the lack of adequate investment in needed infrastructure projects, including fuel-efficient transportation.

"Investments in infrastructure in Brazil do not keep pace with demand because there is no planning," said Carlos Cavalcanti, head of energy and infrastructure at the Federation of Industries of the State of Sao Paulo.

Yet like the other 11 Brazilian cities that will host the 2014 World Cup, Sao Paulo is spending billions of dollars to upgrade its stadium, airport, road and public transport systems to cope with a massive influx of tourists.

The city will host the kickoff game on June 12, 2014.

The city's environment czar Eduardo Jorge is one of the prime movers behind efforts to give the city a sustainable future.

He said unfortunately mass transit has to compete for resources with other key services such as health and education, which together eat up 50 percent of the city's budget.

Jorge however stresses that the subway system is being expanded with four additional lines and the bus fleet being renovated, with 80 percent of its 15,000 vehicles new and energy efficient.

The city's first elevated monorail is under construction to link Guarulhos Airport to the metro system. The $862 million project is due to be completed in late 2014.

Some 2,000 of the new buses operate on ethanol, electricity, biomass or other form of gasoline substitution.

Jorge also points out that Sao Paulo was the first Brazilian city to mandate annual inspection to ensure that vehicles are in good working order and meet pollution control standards.

The city is also promoting cycling by expanding its 55-kilometer biking trail network and offering classes on rules and safety.

On Sundays, another 67 kilometers of lanes are also marked off with cones for use by cyclists in parks and on some of the city's busiest routes.

But speaking in a personal capacity, Jorge said: "The solution to the transportation challenge is to impose severe restrictions on use of cars and motorcycles.

"We need to fine the polluters to discourage superfluous use of cars and secure additional resources to fund public transport," he added.