What does this signpost mean?

The longitudinal deceleration markings of the roadway are a set of diamond-shaped dashed lines parallel to the roadway boundary: the length of the diamond-shaped blocks in the standard section is 1m, the height is 30cm, the spacing is 1m, and the acute angle of the diamond is 45 degrees; Set a gradual change section of 30 meters at the starting position, and the diamond block will be widened from narrow to wide.

The main function: to form a sense of oppression through the visual narrowing of the lane, so that drivers can automatically slow down at corners, ramps and other places that need to slow down.

The dotted line is a variable trajectory, and the solid line is an immutable trajectory.