Work Zone Layout, Setup, and Maintenance
Layout, setup, and maintenance
A work zone layout is built from the TTC plan and adjusted in the field. Start with the advance warning area, then the transition taper, the activity area, and the termination area. The activity area includes the work space, buffer space, and traffic space. Buffer space is a clear recovery area between traffic and workers; it is not storage for equipment or materials. Lateral offset, taper length, device spacing, and buffer length all depend on speed and the type of closure.
For lane closures, use a merging taper to shift traffic, a longitudinal buffer before the work space, and a downstream taper or termination area to return traffic. For shoulder work, keep workers and equipment outside the traveled way where possible; if workers intermittently enter the lane, use warning signs and a flagger or adequate channelization. Pedestrian and bicycle routes must be maintained, accessible, and separated from work activity when feasible.
Traps: placing the work space inside the buffer; forgetting the termination area; setting devices only for cars and ignoring pedestrians, cyclists, and trucks; and leaving gaps in channelization that let drivers cut through the work space.
Worked example: for a right-lane closure, place advance warning signs first, then the merging taper, then a buffer, then the work space, and finally a downstream taper. Verify that the buffer is clear and that the taper does not end directly at the work crew.
Rule of thumb: set up and maintain the zone so a driver who makes a mistake still has a buffer before reaching workers; if that buffer cannot be provided, add positive protection or close more of the roadway.