Rumble strip and method and apparatus for cutting same

A cutting head for milling depressions in a road surface, comprising:

• a drum having opposed ends and a center rotational axis extending between said opposed ends, said drum having a convex outer surface in a direction along said center rotational axis;
• a shaft extending from said opposed ends of said drum along said center rotational axis;
• and
• a plurality of milling elements positioned on said outer surface of the drum and having cutting surfaces positioned to define a plane curve as said drum is rotated about said center rotational axis.

A rumble strip milling machine comprising:

• a vehicle movable along a road surface;
• a cutting head rotatably mounted in associated with said vehicle and mounted for alternating up and down movement, said cutting head comprising:
• a drum having opposed ends and a center rotational axis extending between said opposed ends, said drum having a convex outer surface in a direction along said center rotational axis;
• a shaft extending from said opposed ends of said drum along said center rotational axis;
• and
• a plurality of milling elements positioned on said outer surface of the drum and having cutting surfaces positioned to define a plane curve as said drum is rotated about said center rotational axis;
• and
• a motor coupled with said shaft of the cutting head for effecting rotation thereof.

A method of milling spaced apart rumble strip depressions into an upper surface of a road, said method comprising the steps of:

• (a) providing a cutting head rotatably mounted in associated with a milling machine, said cutting head comprising:
• a drum having opposed ends and a center rotational axis extending between said opposed ends, said drum having a convex outer surface in a direction along said center rotational axis;
• a shaft extending from said opposed ends of said drum along said center rotational axis;
• and
• a plurality of milling elements positioned on said outer surface of the drum and having cutting surfaces positioned to define a plane curve as said drum is rotated about said center rotational axis;
• (b) rotating said cutting head at a preselected rotational speed about said center rotational axis;
• (c) moving said rotating cutting head down into a road surface a preselected distance to mill a depression having a concave bottom that curves upwardly along perpendicular first and second axes;
• (d) moving said cutting head in an upward direction and advancing the milling machine along the road surface;
• (e) repeating steps (c) and (d) to form a plurality of said depressions in spaced apart relationship.