The Street’s Secret Code

What asphalt tags say about the city

Paul Lukas
5 min readAug 15, 2014


We’re often told that urban streets conceal a hidden subterranean world of water mains, sewer lines, electrical wiring, and more. But the surface of the urban roadway — the blacktop that we navigate each day by car, bike, and foot — presents a complex world of its own. Where the untrained eye may see only pavement, lane markers, and crosswalks, a person who knows how to “read the street” will see painted codes and symbols, markings on manhole covers and storm drains, and small but telling records of construction work, all of which combine to form a language that tells the street’s story.

In New York, where I happen to live, that language includes a particularly intriguing element: a series of circular plastic markers embedded in the roadway, each measuring an inch and a half across. Appearing in a variety of colors and stamped with a jumble of words and numbers, they have a bit of Pop Art feel, sort of like poker chips. Once you start noticing them, you can’t stop — they appear on virtually every block. At first glance they seem to be randomly distributed, but upon closer inspection it becomes apparent that they appear only on asphalt patches — spots where the roadway has been torn up by a utility or contractor and then repaved.

These markers are called A-tags (short for asphalt tags). They’re more commonly used in other municipalities as “Call Before You Dig” warning markers, but in New York they’ve been adapted to create a recordkeeping and accountability system. When a utility or contractor is issued a permit to excavate a hole or trench in the roadway — something that happens about 280,000 times a year in New York — the asphalt patch that’s applied at the end of the job must include an embedded A-tag. Each tag has three anchor legs, which, along with a bit of epoxy, help keep the tag in place. The number at the center of the tag indicates the year of the job (“12" for 2012, “14" for 2014, etc.), each broad contracting category has its own color, and each individual contractor or utility is identified either by name or by a unique five-digit number. All of this allows city officials to identify who worked on a given patch, which comes in handy if, say, the patch is starting to sink or buckle and the contractor needs to come back and fix it, or if someone is suing the city after a street-related accident and wants to know the names of everyone who worked on a particular block in the past five years.

A-tags identified by name: NYC Water Works (left), Con Edison (right)
A-tags identified by unique five-digit number

“Before the A-tags, we used painted marks,” says Joseph Yacca, Director of Operations for the New York City Department of Transportation, who helped initiate New York’s A-tag program in 2006. “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.”

Yacca says contractors like the A-tags, too. “There was initially some resistance, because they viewed it as another annoying regulation, but now they’ve seen the value of it,” he says. “Let’s say three or four contractors have been working on a new row of townhouses. There may have been violations issued to the wrong person because they were in the same area. This new system solves that problem.”

Painted green marker
Examples of street asphalt patches with green and blue A-tags

These practical considerations aside, A-tags also allow laypeople to have a greater understanding of their surroundings. Once you understand the system, you can start to fit the pieces together: “Oh, here’s where they must have put in a gas line for that new house. And this is where they connected the sewer line. And this must be from when they installed that new traffic light.” And so on.

A-tags were patented and brought to market in the late 1980s by a Minnesota-based company called Rhino Markers, which continues to sell them today. Tom Preston, a Rhino executive, describes the little markers with a mix of nonchalance and pride. “You know that little plastic thing that holds up the center of a pizza box? It’s basically a glorified version of that,” he says. “But it’s been a really good success story — we solved a problem for New York City.”

Indeed, New York’s A-tag experience has been so positive that Boston officials started a similar program for their own streets in 2011. “It started when the mayor at the time [Thomas Menino] drove over a patch that had settled, and he wanted it fixed,” says Mark Cardarelli, Supervisor of Utility Coordination and Compliance at the Boston Public Works Department. “He called our department and we couldn’t identify who had done the patch. I checked with all the utilities, and they all said, ‘It wasn’t us!’ So I went online and saw that New York City was using these color-coded tags. I gotta give them credit for coming up with that.”

Three years after the Boston program’s implementation, Cardarelli is now a full-fledged A-tag evangelist. “It’s a no-brainer!” he says. “I don’t understand why every city hasn’t done it.” That sentiment may be catching on: Tom Preston, the Rhino Markers exec, says he’s recently received A-tag inquiries from officials in Chicago, Pittsburgh, and Montreal, so residents of those cities may soon be able to do some street-reading of their own.

A-tags — always under foot

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Paul Lukas

I specialize in writing about (and obsessing over) inconspicuous details that other people don’t notice. In short: professional minutiae fetishist.