§ 1128. Driving on roadways laned for traffic. 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.

(b) Upon a roadway which is divided into three lanes and provides for
two-way movement of traffic a vehicle shall not be driven in the center
lane except when overtaking and passing another vehicle traveling in the
same direction when such center lane is clear of traffic within a safe
distance, or in preparation for making a left turn or where such center
lane is at the time allocated exclusively to traffic moving in the same
direction that the vehicle is proceeding and such allocation is
designated by official traffic-control devices.

(c) When official traffic-control devices direct slow-moving traffic,
trucks, buses or specified types of vehicles to use a designated lane or
designate those lanes to be used by traffic moving in a particular
direction regardless of the center of the roadway, drivers of vehicles
shall obey the directions of every such sign, signal or marking.

(d) When official markings are in place indicating those portions of
any roadway where crossing such markings would be especially hazardous,
no driver of a vehicle proceeding along such highway shall at any time
drive across such markings.