Idaho State Statutes - Idaho Attorney Directory

Whenever any highway has
been divided into two (2) or more clearly marked lanes for traffic the
following, in addition to all else, shall apply:
(1) A vehicle shall be driven as nearly as practicable entirely within a
single lane and shall not be moved from that lane until the driver has first
ascertained that the movement can be made with safety.
(2) Upon a highway which is divided into three (3) 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 the center lane is clear of traffic within a safe distance, or
in preparation for making a left-turn or where the center lane is at the time
allocated exclusively to traffic moving in the same direction that the vehicle
is proceeding and the allocation is designated by a traffic control device.
(3) Traffic-control devices may be erected directing specified traffic 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 highway and drivers
of vehicles shall obey the directions of every device.
(4) Traffic-control devices may be installed prohibiting the changing of
lanes on sections of highways and drivers of vehicles shall obey the
directions of every device.

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