Markings on Roads of Kirkland, WA ??

Will anybody respond to my query regarding markings on roads of Kirkland, Redmond, Bellevue, Seattle, Tacoma, Everette and adjoining towns?

I tried to know but could not get any answer to my question through local sources.

The image of marking is as below:



~~ My presumptions;

1. Optical Fibre (Under Ground)
2. GPS Sensors
3. Sewage direction
4. Markings to attend to road repairs

The marking is seen at several places, near traffic signal points, Zebra Xing, LEFT/ RIGHT turn indicators and others road meeting points.