Final answer:
Warning signs and channelizing devices may be omitted when the work space is behind a barrier, more than 2ft behind the curb, or 15ft from the edge of any roadway. These exceptions are based on the principle that if the work zone is sufficiently isolated from the flow of traffic, the need for warning signs and channelizing devices is reduced.
Step-by-step explanation:
Warning signs and channelizing devices are typically used in road construction to alert drivers to the presence of a work zone and to guide them through it safely. However, there are certain scenarios where these signs and devices may be omitted. One such scenario is when the work space is behind a barrier, which provides a physical separation between the work zone and the roadway. Another scenario is when the work space is more than 2ft behind the curb, which creates a safe distance between the work zone and the edge of the roadway. Additionally, warning signs and channelizing devices may be omitted when the work space is 15ft from the edge of any roadway. These exceptions are based on the principle that if the work zone is sufficiently isolated from the flow of traffic, the need for warning signs and channelizing devices is reduced.