A. Required; Exceptions: Upon all roadways of sufficient width a vehicle shall be driven to the right of the center of the roadway, except as follows:
1. When overtaking and passing another vehicle proceeding in the same direction under the rules governing such movement;
2. When the right half of a roadway is closed to traffic while under construction or repair;
3. Upon a roadway divided into three (3) marked lanes for traffic under the rules applicable thereon; and
4. Upon a roadway designated and sign-posted for one-way traffic.
B. Two Roadways: All vehicles shall keep to the right roadway on all streets or highways which are divided into two (2) roadways.
C. Less Than Normal Speed: Upon all roadways, any vehicle proceeding at less than the normal speed of traffic at the time and place and under the conditions then existing shall be driven in the right-hand lane then available for traffic, or as close as practicable to the right-hand curb or edge of the roadway, except when overtaking and passing another vehicle proceeding in the same direction or when preparing for a left turn at an intersection or into a private road or driveway. (1988 Code § 15-502)