Whenever any roadway has been divided into two or more clearly marked lanes for traffic, the following rules in addition to all others consistent herewith shall apply.
(a) A vehicle shall be driven as nearly as practicable entirely within a single lane and shall not be moved from such lane until the driver has first ascertained that such movement can be made with safety, and on highways with four or more lanes, said vehicle shall be driven within the extreme right-hand lane except when overtaking and passing, but in no event shall cross the centerline of the highway except where making a left turn.
(b) Upon a highway which is divided into three (3) lanes a vehicle shall not be driven to the left of the center lane, except when making a left turn and shall not be driven in the center lane except when overtaking and passing another vehicle where the roadway is clearly visible and such center lane is at the time allocated exclusively to traffic moving in the direction the vehicle is proceeding and is sign-posted to give notice of such allocation.
(c) Official signs may be erected directing slow- moving traffic to use a designated lane or designating those lanes to be used by traffic moving in a particular direction regardless of the center of the roadway and drivers of vehicles shall obey the directions of every such sign.
(Ord. 894, passed 1-5-1950)