How quickly did people flock to a newly pedestrianized Times Square, after New York City revamped it four years ago? "We put out the orange barrels and people just materialized into the street," said NYC DOT head Janette Sadik-Khan. "It was like a Star Trek episode."

In a TED talk recorded last month (see video below), Sadik-Khan talked about the changes she's brought to New York's streets since becoming the city's transportation commissioner in 2007.

Her visual-heavy presentation covers the city's pedestrian plaza program, bike lanes, and the recent launch of the city's bike share program.

Sadik-Khan's advice: move swiftly, try temporary changes, and use inexpensive materials. "You can have fun with paint," she said.

And remember that sometimes people need to sit down. She showed a snapshot of two people trying to perch atop a fire hydrant. "Not the mark of a world-class city," she said wryly.