Traffic backing up for miles into downtown and standing still on the Congress Avenue Bridge. Cars and pedestrians vying for space on streets. Lines curling a dozen deep to get inside packed restaurants.

South by Southwest usually brings thousands of people into downtown Austin during the annual music, film and interactive festival.

But it is particularly bursting with tourists and other revelers this year, raising concerns about safety and, in some cases, causing tempers to flare.

"The traffic is outrageous," said Austin beer distributor Jorge Rangel, who drives a large delivery truck to more than 200 bars and clubs downtown. "You name it — cars, bicycles, pedicabs, skateboards and people competing for the road. I have to be alert at all times and looking in the rearview mirror."

Austin police said Friday that they have received no reports of serious injuries among SXSW revelers. But some on the street said they have had close calls in recent days.

"I rented a bike to get around, and I've almost been killed a couple of times," said Jimmy Bryson of Ontario. He said he was bumped by a man in a car who yelled at him to get off the road.

"I just think there are too many people out here," he said.

SXSW officials declined to comment Friday on the crowds. However, executive director Mike Shea said in an interview the week before the event that attendance has soared 20 to 30 percent in each of the past two years. He said organizers contracted with 73 hotels this year, the most ever, and had to scramble at the last minute to find another 400 to 500 rooms.

Austin police said Friday that the city might seem more crowded during the festival this year because it is.

They cited Shea's statistics but also questioned whether construction on downtown streets might be affecting traffic flow.

Brazos Street north of Sixth Street is under construction, and there have been lane closures, city officials said.

"It diminishes the ability to park and the area where you can travel," Assistant Police Chief Patti Robinson said.

And some attributed the crowds to an overlap of the interactive and music portions of the event.

The music festival has historically started on Wednesday, but last year, organizers began it on a smaller scale on Tuesday — the last day of the interactive festival. This year, they added a few more showcases to Tuesday's music lineup, and they added a tech conference to this year's interactive offerings on Wednesday and Thursday after the music festival was in full swing and thousands of people had poured into the city for concerts.

Austin police officials said Friday that they have an appropriate number of officers patrolling downtown but declined to release that number.

Officers are tasked with monitoring barricades to make sure motorists do not drive through them and with enforcing laws, including those involving public intoxication. Some officers are already on duty and assigned to downtown during the festival, but police said organizers pay off-duty officers overtime to help patrol.

SXSW hires private security officers to patrol certain areas, including Thursday night's performance of the Strokes at Auditorium Shores, where attendees at a concert knocked a fence down when officials closed entry.

Revelers then surged toward the stage, said Michael Mansfield, who was at the concert.

"It got out of control," Mansfield said. "I was literally swept off my feet. And when I started feeling people push forward, I knew this was going to be bad."

Austin-Travis County Emergency Medical Services spokesman Warren Hassinger said he was not aware of any injuries at the concert.

This week, the city announced that for the second year in a row, a special enforcement team would be "checking that all vendors, merchants, event holders and property owners are in compliance with municipal safety codes."

It was unclear Friday how many violations the team had found and how many resulted in citations.

City spokeswoman Melissa Martinez said no one is tracking the collective efforts of the team, which includes six city departments, the Texas Alcoholic Beverage Commission and the Texas Department of Public Safety. In some cases, Martinez said, inspectors were trying to help venues and vendors take the necessary steps to comply with city rules. Martinez referred questions about the number of citations to individual departments.

Additional material from staff writers Ricardo Gandara, Shonda Novak and Marty Toohey.