Traffic chaos spread throughout downtown Miami Tuesday when the southbound span of the heavily traveled Brickell Avenue drawbridge became stuck in the up position after the locking mechanism sustained damage during a test operation at dawn.

Florida Department of Transportation officials said they did not know how long emergency repairs would take, but indicated it could be several days until the southbound lanes reopen. The northbound lanes remained open Tuesday.

“Oh, my God. It was awful,” said Therese Gagné, a commuter who was near the Brickell Avenue bridge returning home to Key Biscayne from Miami Beach. “Cars were cutting each other off. I was stuck for more than 15 minutes before I was able to loop around and head north on U.S. 1 and then get onto I-95 to avoid the mess. I’m never taking this bridge again.”

However, the Miami Police Department said Tuesday evening it expected the bridge to be closed in both directions for several days while FDOT worked around the clock to complete the repairs. It designated the following detours:

• Southbound drivers should head west on Southeast Second Street to South Miami Avenue, turn south and continue to Southeast Eighth Street, and then head east to return to Brickell Avenue.

• Northbound drivers should turn west on Southeast Seventh Street from Brickell Avenue, continue to South Miami Avenue and then turn north to cross the river. They should remain in the right lane to First Avenue and continue to Southeast Third Street. From there, they should turn east to reach U.S. 1.

Drivers can also bypass the area completely by taking Interstate 95, a bit farther west.

Also Monday evening, FDOT said the bridge had been reopened to river traffic.

While traffic backups are common whenever the drawbridge opens for boats, Tuesday’s delays were extraordinary because traffic continued to build up after the southbound span failed to close properly during the test.

For years, the bridge has been the bane of commuters who work or live in the high-end Brickell Financial District, home to banks, investment houses, real estate agencies, office buildings and pricy condominiums.

In 1999, then-Miami Mayor Joe Carollo pushed FDOT to tear down the bridge and build a tunnel under the Miami River. FDOT officials rejected the idea as unfeasible both because of the cost and the amount of land that would be needed.