Just days before world leaders will meet in Pittsburgh for the Group of 20 economic summit, protests were under way in the city.

Many people spent the weekend marching through downtown, some from hundreds of miles away. The protesters said they are marching to raise awareness about the current state of the global economy and high unemployment rates.

A total of 27 roads will be closed during the summit when the transportation safety plan goes into effect at 12:01 a.m. Thursday. It will end on Friday after authorities have determined dignitaries have left.

The only exception to public transit vehicles will be those providing medical or certain business deliveries, taxi cabs, hotel shuttles and postal and parcel deliveries.

People who live downtown will be able to drive into the area only if they present a driver's license showing a downtown address. Business district workers will not be allowed to drive in, and instead will be encouraged to park on its periphery and take public transit or walk into downtown.

Vehicles that do enter downtown will have to go through one of three checkpoints at the Smithfield Street Bridge, Fifth Avenue at Ross Street and the Roberto Clemente Bridge.

The Pennsylvania State Police, Allegheny County police, the Pennsylvania Department of Transportation and the Port Authority of Allegheny County helped develop the plan.

The following is a list of roads that will be used for emergency purposes only:

-- Fort Duquesne Boulevard
-- Stanwix Street
-- Grant Street
-- Second Avenue
-- Sixth and Seventh avenues in the area of Mellon Arena
-- All ramps from interstates to downtown Pittsburgh

People will still be able to walk and ride bicycles downtown and outside of the Secret Service perimeter around the convention center.

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