What is the purpose of the blue reflectors in the middle of the roadways?
Those blue reflectors, or retroreflective raised pavement markers (RRPMs), are placed near intersections where fire hydrants are present. To stand out, most hydrants traditionally are painted a bright red, and a yellow "No Parking" line is painted on the adjacent curb. Because paint fades, blue RRPMs are installed as a way to make the hydrants visible to firefighters in foggy or smoky conditions or where traffic can be an issue.
Some cities have begun to employ digital technology and GPS mapping of their hydrants to assist fire companies. Capt. Edwin Holmes at the New Orleans Fire Department headquarters on Decatur Street, however, says it is the job of the fire company to know where every fire hydrant in the district is located; our firefighters therefore don't depend on the blue reflectors. Besides, there aren't reflectors near all the hydrants in the city, so that strategy would be unreliable in an emergency.
In some places, neighborhood associations buy the reflectors or individual fire companies supply them. In New Orleans, installing RRPMs was an initiative of the Sewerage and Water Board.