At road works, advance warning is critical for road users, giving them time to process information and slow down on the immediate approach to the work area.

The advance warning area is the section of highway where road users are informed about the upcoming work zone or incident area. The Lane(s) Closed sign must be used in advance of that point where one or more through lanes of a multi-lane roadway are closed.

A study of work zone crashes (Akepati, & Dissanayake, 2011) found that majority of work zone crashes occurred in the activity area of the work zone where the actual work happens. The lane closure type of work zone is the one where most of the work zone crashes occurred. Multiple vehicle crashes and rear-end collisions were also more predominant in work zones. 

Source: dailymotion