Federal and local officials are not taking chances with security as they investigate a detailed al-Qaida car bomb plot aimed at bridges or tunnels in New York or Washington, but Mayor Michael Bloomberg said while New Yorkers should be vigilant they should not change their everyday routine.
The Department of Homeland Security says the "credible" terror threat against the city is timed to coincide with the 10th anniversary of the September 11th attacks.
Security has been increased at the city's major transit hubs, bridges, tunnels, landmarks and houses of worship, although much of those precautions were being taken anyway ahead of Sunday's anniversary.
The mayor has stressed that even though the threat is credible, it has not been corroborated, and September 11th anniversary ceremonies will be held as scheduled.
Police Commissioner Ray Kelly said he has increased surveillance of bridges and tunnels and set up vehicle checkpoints and doing bomb sweeps of parking garages.
Counterterrorism, transit and highway officers will work 12-hour shifts for several days, bag inspections are increasing in subway stations and the police are using more patrol vehicles with plate readers, bomb-sniffing dogs and radiation-detecting equipment.
Police are also towing illegally park cars.
Many highways from the George Washington Bridge down to Canal Street have backed-up, bumper-to-bumper traffic due to security checkpoints, as police inspect around and underneath vehicles.
One truck driver on the West Side Highway told NY1 he had been stopped five times today.
Columbus Avenue and other avenues on Manhattan's West Side have been shut down to one lane of traffic to make checkpoints possible.
At Pennsylvania Station, there is no dramatic increase in security, but Port Authority police, the NYPD, the National Guard and other law enforcement agencies are on alert.
"Six or seven Amtrak police with very heavy-duty armor and guns," said an Amtrak passenger from Albany. "Got off the train and there were police everywhere, along with a dog as well."
The World Trade Center site also has extra NYPD and Port Authority officers and one of the NYPD's so-called "Eye In The Sky" units parked nearby.
Bloomberg said the city's increased security measures will not always be noticeable to laypersons.
Homeland Security officials said that information gathered during the raid on Osama bin Laden's compound in Pakistan showed al-Qaida was looking into attack the United States again, and was considering an attack on the anniversary of September 11th.
President Barack Obama will still visit the World Trade Center site, the Pentagon and Shanksville, Penn. on Sunday to observe the September 11th anniversary.