The Baltimore Grand Prix lurched toward its starting line Thursday as downtown was consumed by the chaos of last-minute preparations for the three-day event.

Wide-scale road closings began to take effect, preparing the race course along downtown streets for high-speed practice runs. And that forced businesses, schools and residents to adjust routines to cope with the blocked roads and walkways, public transit changes and increased traffic near the track.

But getting downtown Baltimore to grind to a halt was no easy task. Just ask Phil Giebler, a racecar driving coach who was bewildered as he previewed the course in a golf cart and had to contend with cars coming off the Baltimore-Washington Parkway. He's been on street-racing track previews before, but never with commuters.

"And we're stuck in traffic in the track," said Giebler, his golf cart coming to a stop. "This should be closed down."

Pedestrians also had to adjust to the last-minute preparations. Some streets were virtually empty, while others used as detours were jammed with cars.

"Actually you feel safer down here because there are not as many cars on the street and there are lots of people around," said Bel Air resident Stephanie Walker, who was walking behind the Baltimore Convention Center with her daughter.

"I'm not sure how we'll get back," said Jennifer Walker, who lives in Otterbein and said the walk between her home and downtown had become a maze of chain link fences and concrete barriers.

All around downtown, people were squeezing through gaps in the blockades and jaywalking, cars were ignoring traffic cones, and frantic Grand Prix security guards, city police and state troopers were trying to keep order.

Downtown resident Angie Sanders was riding her scooter down Charles Street, which was limited to one lane, and was first in line waiting at the red light at Pratt Street.

"With a scooter I can get through anything," Sanders said, adding that she wasn't too inconvenienced by the race. She turned right onto Pratt, which appeared closed, and several cars followed her lead before a guard put a stop to it.

Several large employers allowed employees to work remotely or make other arrangements to avoid the roadblocks and traffic tie-ups.

Employees for money manager T. Rowe Price were allowed to work from the company's Owings Mills campus, its business center in Linthicum or their homes Wednesday through Friday, said spokeswoman Heather McDonold.

Verizon spokeswoman Sandra Arnette said that most employees were working in other offices, such as Hunt Valley, Silver Spring or Washington. Others were telecommuting.

Arnette said that employees who choose to work downtown will still be able to get to their offices, but the building's doors will be locked and security will be checking identification.

"Because it's been so hard, especially the closer you get to the weekend, we were told we could work elsewhere, which made it more convenient," she said.

But employees who planned to still come to the downtown office or were simply attending the race were told that if they wanted to park in the garage, they had to arrive before 7 a.m. and could not leave until after the race, Arnette said.

Constellation Energy Group, too, is providing flexibility, particularly for employees commuting from the south, said spokesman Larry McDonnell. About 1,500 employees are based at Constellation's Pratt Street headquarters and adjacent building. With a BlackBerry in hand, McDonnell was working at home Thursday and planned to do the same on Friday.

Gary McLhinney, a former Baltimore police union president who now works for a downtown law firm, said the Inner Harbor offices were as empty as during holidays.

Only a quarter of the spaces in the outdoor parking lot at East Pratt and Commerce streets were full, he said. He walked to Harborplace for lunch, and only a few outdoor tables at M&S Grill were occupied. McLhinney said he usually makes a reservation when he wants to go there for a business lunch.

His law firm will be closed Friday. "They had to give them the day off," he said. "You can't expect them to make it in."

Six Baltimore schools near the Grand Prix track were scheduled for a one-hour delayed opening Friday as well, further shortening the first week of school, which had been hampered by power outages following Hurricane Irene.

The Orioles saw light attendance at an early-afternoon game Thursday.

Street vendors who normally encircle the stadium were nowhere to be seen, driven from their city-assigned spots by grandstands and fences. Vendors who wanted a place inside the race course during the weekend had to pay upwards of $2,000, said Lonnie Fisher, the race's assistant general manager.

"It was a little sad, actually," said Megan Johnson of Cecil County, disappointed by the atmosphere surrounding the Orioles game.

"We didn't even know the race was going on," said Johnson's friend Ray Cowan, from Northern Virginia, who said traffic coming into the city before the game was "horrible."

Martin Luther King Jr. Boulevard, which the city is relying on for incoming highway traffic, was slowed all day Thursday by re-routed traffic. Delays on that street are expected for the whole weekend, as Light Street, Interstate 395 and Russell Street will be closed Friday.

Public transportation will also be significantly disrupted by the Grand Prix course.

The Purple Route of the Charm City Circulator routes will be split in two by the race, which will close Light Street at Pratt. The eastbound part of the Orange Route loop will shift from Pratt Street to Baltimore Street.

The light rail line between BWI-Marshall Airport and downtown will be split because the race course crosses the line at Camden Yards. A shuttle bus will be provided.

"It's exciting because it's actually in the downtown area," said Team Moore driving coach Giebler, who compared the setting to Monaco. Most city races, he said, take place on less-traveled streets on the outskirts of downtown.

But he and some drivers did not like having to tour a track crowded with pedestrians and commuters, less than 24 hours before high-speed practice began.

"The problem is we can't get a good view of the track," said driver Shannon McIntosh. As she tried to walk the route with her crew, a bike messenger flew by and passengers from the light rail and MARC trains flowed to and fro down the track. "I imagine the construction people will be up all night finishing this."

Gustavo Yacaman, a driver with Team Moore, was also perturbed that he couldn't see the intricacies of the track surface because vehicles and pedestrians were still moving along the pavement.

"The track should be ready by now," said Yacaman. He pointed to barrier walls that were not complete and parts of the track that still needed asphalt. "This is how it should look … a week out, not 12 hours before the first session."

Giebler and Yacaman had not been told by Grand Prix organizers that the track would still be in use during the walk-through. Yacaman had to pull his cart over as he approached the pit lane along the east side of the Camden Yards warehouse so he could ask a worker putting down asphalt what the final surface was going to look like.

Belardi Auto Racing driver Anders Krohn was concerned that asphalt being laid Thursday would not be "cured," or hardened, in time for the races. The cars create suction that can easily rip up fresh asphalt, especially on corners, Krohn said.

"Oh my goodness, this is bumpy," said Krohn, who also questioned the exposed Light Rail tracks and the uneven concrete surfaces throughout the course.

But race organizers discounted the concerns.

"The track will absolutely be ready," said Amy Konrath, a spokeswoman for IndyCar. As of Thursday night, the early Friday practice schedule had not been altered to allow for more time to finish construction. "They're working around the clock."