Figure 6C-1. Component Parts of a Temporary Traffic Control Zone
This image illustrates the component parts of a temporary traffic control (TTC)
The diagram shows the set up for a temporary traffic control zone for a two-lane
roadway where both lanes are traveling in the same direction and are separated
along the length of the image by a broken white pavement marking line. Arrows
denoting direction of travel are shown in each lane pointing upward. Left and
right shoulders shown to the outside of the two travel lanes. The left lane
is shown with a solid yellow pavement marking line along the left side of the
lane, separating it from the left shoulder, that runs the full length of the
figure. The right lane is shown with a solid white edge line pavement marking
separating the right shoulder from the right lane. The white line bows out to
the left, toward the broken center line that divides the two lanes, delineating
the outline of the TTC zone. To the immediate right of the bowed section of
white line and running parallel to it is a series of yellow channelizing devices
runs. This line of channelizing devices continues upward, runing along the center
line for the length of the traffic control zone area before returning, in a
diagonal line, back to right shoulder at the end of the TTC zone.
Four component parts of a temporary traffic control zone are illustrated on
the right side of this figure, which are described as follows:
- At the bottom of the figure, the first component part of a temporary traffic
control zone is labeled the "Advance Warning Area tells traffic what
to expect ahead." This area includes a series of yellow channelizing
devices running from the right edge of the right shoulder to the white line
that defines the right edge of the right travel lane. Two equally spaced symbols
representing sign locations are positioned along the right and left side of
the road equally spaced apart in the advance warning area.
- Directly following the advance warning area (traveling upward, in the direction
of traffic), the next component part of the temporary traffic control zone
is labeled "Transition Area moves traffic out of its normal path."
In this area along the roadway, a solid white line bordered by yellow channelizing
devices runs diagonally from the right edge of the roadway to the center line
of the roadway.
- Directly following the transition area traveling upward, the next component
part of the temporary traffic control zone is shown, labeled the "Activity
Area is where work takes place." The activity area is divided into buffer
space and work space. The buffer space, in the lower part of the activity
area, has two labels, the first of which refers to the length of the zone
and the second of which refers to the space to the left of the activity area
where traffic is separated from the activity area. They read, "Buffer
Space (longitudinal) provides protection for traffic and workers" and
"Buffer space (lateral) provides protection for traffic and workers."
The work space, located directly following the buffer space (longitudinal),
is labeled "Work Space is set aside for workers, equipment, and material
storage." This space is illustrated as a rectangle with hash marks along
the center part of the closed right lane. Throughout the activity area, the
open lane of traffic is labeled "Traffic Space allows traffic to pass
through the activity area." Along the left side of the activity area,
to the right of and parallel to the solid white line pavement markings, a
series of equally spaced channelizing devices are shown.
- Directly above the activity area traveling upward, the next component part
of the temporary traffic control zone is labeled "Termination Area lets
traffic resume normal operations." The termination area is divided into
three successive spaces; the lower space is labeled "Buffer Space (longitudinal)."
Within the buffer space (longitudinal), a solid white line and a series of
channelizing devices runs along the center of the roadway. Directly above
the buffer space (longitudinal) a solid white pavement marking line and series
of channelizing devices runs diagonally from lower left to upper right, forming
the "Downstream Taper." Directly above the downstream taper area,
the solid white edge line is shown to continue running straight up to the
end of the area labeled "Termination Area" and beyond, to the end
of the figure, separating the right edge of the travel lane from the right
shoulder area. Two symbols representing road signs arelocated on the left
and right sides of the road, at the upper end of the termination area.
The image legend indicates that orange squares stand for channelizing devices,
arrows indicate the direction of travel, black "T" shapes represent
road signs, and a rectangle with diagonal hash marks represents the work space.
Return to Figure 6C-1.