How far in advance of a lane drop should the special lane drop markings begin?
For a lane drop on a freeway or expressway, Section 3B.04 and Figure 3B-10 both note that a lane drop marking consisting of a wide, white dotted line, 3 feet in length with a 9 feet gap separation, shall be used and that it should begin at least ½ mile in advance of the theoretical gore of the freeway exit ramp. For lane drops on conventional roads, where a through lane becomes a “trap lane” (that is, a turn only lane), Section 3B.04 states that a lane drop marking consisting of a wide, white dotted line, 3 feet in length with a 9 feet gap separation shall also be used and should begin a distance in advance of the intersection that is determined by engineering judgment as suitable to enable drivers who do not desire to make the mandatory turn to move out of the lane being dropped prior to reaching the queue of vehicles that are waiting to make the turn. The lane drop marking should begin no closer to the intersection than the most upstream regulatory or warning sign associated with the
