|FHWA Policy Memorandums|
This figure shows an example of a two-stage bicycle turn box installed at an intersection where use of the box is optional. For purposes of this description, it is assumed that north is upward in the figure.
Both streets have two lanes, one in each direction, and there are bicycle lanes in all directions. In the eastbound direction has a marked parking lane. Two-stage bicycle turn boxes are located on the north and south sides of the intersection, in front of the southbound and northbound approaches respectively. Green-colored pavement is installed in the two-stage bicycle turn boxes.
NO TURN ON RED (R10-11 Series) signing faces the northbound and southbound approaches. On the eastbound approach, a LEFT TURN MAY USE TURN BOX (D11-20) sign is provided in advance of the intersection. A second D11-20 sign is provided at the intersection, with a note indicating that this placement is optional only if D11-20 is also used in advance of the intersection. On the southeast corner of the intersection, the far side for eastbound traffic, a LEFT TURN BOX (D11-20a) sign is provided with the arrow on the sign indicating the location of the two-stage turn box.
United States Department of Transportation - Federal Highway Administration