The tower now stands at 480 feet, just 45 feet away from reaching its final height, Caltrans spokesman Bart Ney said.
You can see the animation of the tower construction at this link.
Workers started lifting the first piece of the tower Monday and worked nonstop until 1:25 a.m. Friday morning.
"This is a huge milestone," Ney said. "We hope to keep this momentum going until the entire project is completed in 2013."
The fifth tower section, which will connect the four independent tower legs, is scheduled to be lifted into place at the end of March or beginning of April.