Ever wondered what those mysterious spray-painted markings on city streets are all about? They look like some sort of secret code until you start to decipher their meaning and critical importance.  

Spray-painted markings on city streets, sidewalks, and rights-of-way are color-coded and indicate the location of underground utilities that workers need to take into account while doing digging or roadworks.

Red: electric power lines, cables, conduit, and lighting cables.
Orange: telecommunication, alarm or signal lines, cables, or conduit.
Yellow: natural gas, oil, steam, petroleum, or other flammables.
Green: sewers and drain lines.
Blue: drinking water.

You might also see notations like arrows or numbers as part of markings. These are necessary to keep track of the locations, widths, and depths of conduits, cables, and pipes and identify the associated utility company.

All of this is done with a specific type of temporary, environmentally-friendly paint that vanishes within a month.

How did this begin? 

In 1976, construction workers in Culver City, California accidentally hit a petroleum pipeline running under a street, resulting in a fatal explosion that leveled half of a city block. It wasn’t the first or last accident of its kind, but it helped spur the creation of the critical color-coded utility markings called “Uniform Color Codes.” These codes were developed by the American Public Works Association (APWA).

Homeowners Dig Safely

Before you do any type of digging on your property, call 811 or visit digsafelyoregon.com to ensure there aren’t utilities below that you might hit, such as natural gas pipelines, electrical utilities, telecommunication systems, and sewer and water lines. This is a free service to homeowners, contractors, and other excavators, informing them of any buried facilities in the area where they are planning to dig.

If you notice markings on your lawn and didn’t know about it, it’s most likely that either your neighbors are planning some work, a utility operator is planning maintenance or repair, or the City or County is planning excavation work. Utility operators mark any underground line that is directly in the way of construction, or even near it.

Something else to be aware of is that utilities such as telecommunications mark all the way to the house, but utilities such as water, PGE, and NW Natural only mark to their meters.

If there are City-related topics you’ve wondered about and would like to suggest for an upcoming City 101, please let us know.