They are as sure a sign of spring as any red-breasted robin, but they don’t portend fair weather or fresh flowers. No, they’re harbingers of clotted roads, torn asphalt and power tools.

They are spray-painted urban glyphs that signal crews where and where not to dig. As random as they might look, they represent a definitive code:

Red paint means electrical power lines lie somewhere below.

Yellow signals the presence of natural gas, oil or steam lines.

Orange represents telephone or cable TV lines.

Blue signifies drinking water.

Green marks the presence of sewer pipes.

White paint tells crews were to start digging and where to stop.

Arrows show the direction of power, gas and water lines.

Diamonds represent duct structures that contain multiple lines.

Stacked diamonds or lines warn crews to the presence of numerous different utility obstacles.

– Scott Taylor

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