Once you’ve seen one, you won’t be able to ignore them. They look like plastic bottle caps, in bright primary colors, embedded in the city streets. Look closely, and you’ll see they have some sequence of numbers and letters on them. If you’re thinking: must be some kind of secret code for us urban dwellers to figure out, you aren’t far from the mark. Once you start paying attention, you’ll realize the plastic circles only appear where the road has been paved over. The circles, known as asphalt tags, are part of a street code used by those that work beneath the streets. When a section of roadway is patched up, these tags are left behind to denote who did the work.

In New York City, the use of the asphalt tags, “A-tags” for short, began only in 2006. In other cities, the tags usually just say “Call Before You Dig” and possibly the agency or type of activity involved. But in New York City, a system was instituted by the Department of Transportation to provide even more detail. Each permit holder that does work on or under the streets has a five digit identification number which is molded on the outer ring of the A-tag, which must measure between 1.5 and 3 inches in diamter. In the center of the circle, a two digit number denotes the year that the work was done. The agency is further denoted by color: Verizon is cherry red, Empire City Subway (which manages the city’s telecommunications ducts, now owned by Verizon) is chrome yellow, Con Ed is light blue, MTA is purple, FDNY is also purple, cable TV is regal blue, Long Island Power Authority (LIPA) is yellow, signal and street light work is orange, plumbing is green, among others. The permit holders must maintain the tags during the “guarantee” period.

Interviewed for an article on Medium in 2014, Joseph Yacca, Director of Highway Inspection and Quality Assurance Operations for the NYC DOT who launched the A-tag program said: “Before the A-tags, we used painted marks. But the painted marks were just color-coded — they didn’t identify the individual user. For example, every plumber was green, so if you found a green marker, you knew you were looking for a plumber, but you didn’t know who. So we used to have to pull all the old permits and so on. Now we can pinpoint it much faster.” He said it also avoids confusion when multiple contractors are operating in the same area, preventing the wrong people from being issued violations. The NYC DOT rule book puts it simply: after each excavation, the permittee must provide permanent colored markers “for the purpose of easily identifying the permittee’s openings and restorations.”

While this tag says Cablevision, usually, it’s just the series of numbers and letters present. 

Asphalt tags were patented in 1987 and were first sold by the Minnesota company Rhino Markers, from which you can still get them today or from the company Berntsen. Custom A-tags from Rhino cost $1.00 or less if you buy in bulk from 750 units or up. Under the top circle, asphalt tags have three prongs (two anchor legs and a central prong) which are pressed into asphalt or concrete that has been just laid. Some additional innovations for the longevity of the tag include using UV-stable plastic material that resists fading and won’t break down over time, and the tag is slightly recessed so that snowplows won’t accidentally gouge them out. According to the original patent, the tag “can expand and contract with expansion and contraction of the paving material caused by changes in temperature.”

So next time you cross the street, look out for these markers. They’re everywhere!

Next, see what the spray painted symbols on the streets of NYC mean. Discover more of how NYC works in our Cities 101 column.