"According to [utility company Con Edison] spokesman Robert McGee, the blue plastic disk is a Con Ed calling card. It's placed on streets that the utility was responsible for repaving. In some cases, they have numbers in the center; these designate the year Con Ed did the work."
"One of the things that has been attempted over the years is to get the various city agencies...to coordinate on street openings," McGee said. "By getting everyone on the same page, the city can try to minimize the amount of times a street is ripped up," notes Hinds.
"And those yellow letter E's that can be found on city streets and sidewalks? Also Con Ed. E7 means the road was paved in 2007."