Raleigh, N.C. — Hundreds of commuters were stuck in a 10-mile backup in west Raleigh Thursday morning because a motivational seminar at the RBC Center added to traffic congestion, but better planning kept tie-ups to a minimum during the evening rush hour.

More than 18,000 people attended "Get Motivated," a business/motivational event. Speakers included University of North Carolina head basketball coach Roy Williams and former U.S. Secretary of State Colin Powell.

Traffic delays were seen on Wade Avenue, Edwards Mill Road, Trinity Road, Blue Ridge Road and the Interstate 440 Beltline for hours Thursday morning. Traffic on eastbound Interstate 40 was backed up as far as the Durham Freeway exit 10 miles to the west, and westbound I-40 was backed up to the Lake Wheeler Road exit eight miles away.

"Everywhere west of (the Streets at) Southpoint, right at (N.C. Highway) 751, it was bumper to bumper all the way through," driver John Pischak said.

Similar traffic delays were seen after 5 p.m. Thursday when the motivational event ended, but traffic was moving easily an hour later. Raleigh police closed eastbound and westbound ramps on Wade Avenue at Blue Ridge Road at 5:30 p.m. to try to control the traffic flow.

"You take that volume (of people) and throw it out there with the rest of the people trying to get to work, and you get traffic jams," said Dave Olson, general manager for the RBC Center.

Olson said his staff met last week with the state Highway Patrol, the state Department of Transportation and the Raleigh Police Department to devise plans for handling event traffic. Authorities have known for weeks that the event was expected to produce traffic delays, he said.

In fact, a similar event at the RBC Center eight years ago caused a 17-mile traffic jam.

DOT regional engineer Ed Sirgany said authorities underestimated the volume of cars to the event, saying they expected only 12,000 to 13,000 vehicles instead of the 15,000 to 16,000 that showed up.

Also, development near the arena has reconfigured traffic flow on Edwards Mill Road, which has reduced capacity, Sirgany said.

"The traffic moved, but we didn't move fast," seminar attendee Judy Rogers said, noting a trip from north of downtown Raleigh to the RBC Center took an hour Thursday morning instead of the usual 10 minutes.

Most of the people who attended the event drove their own cars, which added to the congestion, Olson said. He suggested that people carpool the next time such an event is held at the RBC Center to cut down on traffic volume.

Some ticket holders were even turned away from the event because the parking lots outside the arena were filled by the time they arrived.

"It took about two hours to get in this morning, but it was worth it," seminar attendee Belinda Fayson said.