Police shut down a sidewalk alongside the Treasury Department yesterday, the latest security measure taken in the District since authorities raised the terror alert level last week in response to threats against financial institutions.

Yesterday's action closed a two-block section of sidewalk on 15th Street NW and a parking lot next to it. Uniformed U.S. Secret Service police also installed metal barriers around a parking lot on the 17th Street side of the White House.

Authorities said they wanted to prevent people from tampering with cars in those lots and to restrict pedestrian access to the Treasury.

Homeland Security Secretary Tom Ridge announced Aug. 1 that officials had received credible information about a terrorist threat to financial institutions in Washington, New York City and Newark.

The Secret Service, which patrols the area around the Treasury, said yesterday's sidewalk closure was a temporary way to address those threats. Authorities announced the sidewalk restrictions last week.

Lorie Lewis, a Secret Service spokeswoman, said officials plan to reevaluate the closure in the "near future."

"We continue to monitor and evaluate ever-changing world events," Lewis said.

In the wake of the terror alert, federal and city officials discussed closing 15th Street NW, a bustling commuter thoroughfare, to truck traffic. But authorities decided not to take that action, for now. They stressed that could change as they assess the security climate.

In the days after Ridge's warning -- which also identified the World Bank and International Monetary Fund in Washington as potential targets -- police in the District began operating dozens of vehicle checkpoints. They restricted parking on some roads and closed a major street.

The U.S. Capitol Police shut down part of First Street NE in response to the threat of truck bombs. They also set up more than a dozen checkpoints aimed at making it difficult for potential bombers to get near congressional buildings.

D.C. police and federal law enforcement officials also started operating checkpoints around the Federal Reserve on Constitution Avenue NW.

Yesterday afternoon, tourists and other pedestrians took the closure in stride, saying they expected the government to take such actions after the 2001 terrorist attacks.

Stuart Visnov, 50, and his two sons were the final people allowed to walk along the sidewalk.

Visnov, a private detective from Worcester, Pa., said he felt that the Secret Service was taking appropriate action in light of current threats. The barriers might "make a difference" in preventing an attack, Visnov said.

"We have to give up some freedoms to be safe," said Visnov, standing next to his sons, Danny, 5, and Eric, 15.

Bernie Finer of Peabody, Mass., and a friend, Yaron Leibel, were playing tourist yesterday as they looked for a better view of the White House. They were not surprised at the decision to close 15th Street's sidewalk.

Leibel was visiting from Israel, a country known for its security measures.

"This is nothing compared to Israel," said Leibel, 25. "In Israel, you can't walk five minutes without getting checked out."

Aliya Wong, left, and other pedestrians hit the street when officers closed the sidewalk.A Secret Service officer directs tourists Bernie Finer, center, and Yaron Leibel near the Treasury Building.