The lighting is the last piece of the Congress Parkway reconstruction project that began in late 2010, according to the Chicago Department of Transportation. About 600 decorative luminaires and towerlike panels that change colors were flipped on along Congress Parkway Thursday night, marking the completion of $24 million in road and streetscape improvements, officials said.

The work included redesigning parts of Congress between Wells Street and Michigan Avenue to improve traffic flow and signal timing for the 63,000 drivers who use the corridor each weekday, officials said. Also, sidewalks were widened, and planters and other landscaping installed, officials said.

The 600 LED lights displayed atop 20-foot pillars on part of the median along Congress are intended to be "visually interesting, but also not distracting" to drivers, said Janet Attarian, a CDOT project director.

Each light fixture can feature any of 16 million colors, she said. But four main color schemes for seasonal and holiday arrangements will be primarily displayed, she said.