The ornamental design for traffic marker, as shown and described.
FIG. 1 is a front elevational view of a traffic marker showing my new
design, with the broken line showing for illustrative purposes only and
forming no part of the claimed design;
FIG. 2 is a right side elevational view thereof, with the left side being a
mirror image;
FIG. 3 is a top plan view thereof; and,
FIG. 4 is a top plan view thereof, with the bottom being flat.