Mayor Bill de Blasio’s traffic safety push yielded perhaps its most significant change early on Friday, when the State Legislature approved a plan to reduce the default speed limit in New York City to 25 miles per hour.

Now comes the hard part: retooling the highly choreographed traffic dance in a city of 14,000 taxis, 12,700 signalized intersections and 6,000 roadway miles.

The city will have some time. The reduction from 30 m.p.h. cannot begin until 90 days after Gov. Andrew M. Cuomo signs the bill into law. (A spokesman said Mr. Cuomo was expected to do so.)

In the interim, transportation officials have begun plotting the details of the change, with plans that include the highly technical, like recalibrating automated enforcement cameras, and the visual.