ATSSA Traffic Control Supervisor Re-certification 100%
VERIFIED ANSWERS 2023/2024
L=(WS²)/60 for 40MPH or less,
L=WS for 45MPH or more
Formula for Min. taper length
The off peak 85th percentile. Which is the speed at or below which 85% of
vehicles travel operating speed in free flow conditions
speed used in formulas should be
125'
Distance of L for 25 MPH with 12' Lane width
245'
Distance of L for 35 MPH with 12' Lane width
540'
Distance of L for 45 MPH with 12' Lane width
660'
Distance of L for 55 MPH with 12' Lane width
780'
Distance of L for 65 MPH 12' Lane width
L Minimum
Merging Taper Length
1/2 L Minimum
Shifting Taper Length
1/3 L Minimum
Shoulder Taper Length
50'-100' regardless of speed
6 devices 10'-20' apart
One-Lane, Two-Way Taper (Flagger taper) Length and number of devices
50'-100' per lane
, Downstream taper Length
2L
Tangent distance (between tapers)
1/2L
Tangent distance before shifting taper
Buffer Space
Work Space
Traffic Space
Activity Area Sub-components (3)
Recovery Area for errant vehicles: Forgiving design
Protects workers and Motorists
Always completely empty or clear
No vehicles, truck-mounted attenuator, equipment, or materials
STRONGLY RECOMMENDED: unless there is a documented reason not to
Longitudinal Buffer Space
Where road users are returned to their normal path
extends from the downstream end of the work area to the last device such as end
work zone sign
May contain:
end work zone sign: usually 500' past last device
downstream taper = 50'-100' per lane
Termination Area is:
can contain: (2)
100'
Recommended Advanced Warning Sign Spaceing: Urban (low speed)
350'
Recommended Advanced Warning Sign Spaceing: urban (high speed)
500'
Recommended Advanced Warning Sign Spaceing: Rural
1000', 1500', and 2640'
Recommended Advanced Warning Sign Spaceing: freeways and expressways (3)
VERIFIED ANSWERS 2023/2024
L=(WS²)/60 for 40MPH or less,
L=WS for 45MPH or more
Formula for Min. taper length
The off peak 85th percentile. Which is the speed at or below which 85% of
vehicles travel operating speed in free flow conditions
speed used in formulas should be
125'
Distance of L for 25 MPH with 12' Lane width
245'
Distance of L for 35 MPH with 12' Lane width
540'
Distance of L for 45 MPH with 12' Lane width
660'
Distance of L for 55 MPH with 12' Lane width
780'
Distance of L for 65 MPH 12' Lane width
L Minimum
Merging Taper Length
1/2 L Minimum
Shifting Taper Length
1/3 L Minimum
Shoulder Taper Length
50'-100' regardless of speed
6 devices 10'-20' apart
One-Lane, Two-Way Taper (Flagger taper) Length and number of devices
50'-100' per lane
, Downstream taper Length
2L
Tangent distance (between tapers)
1/2L
Tangent distance before shifting taper
Buffer Space
Work Space
Traffic Space
Activity Area Sub-components (3)
Recovery Area for errant vehicles: Forgiving design
Protects workers and Motorists
Always completely empty or clear
No vehicles, truck-mounted attenuator, equipment, or materials
STRONGLY RECOMMENDED: unless there is a documented reason not to
Longitudinal Buffer Space
Where road users are returned to their normal path
extends from the downstream end of the work area to the last device such as end
work zone sign
May contain:
end work zone sign: usually 500' past last device
downstream taper = 50'-100' per lane
Termination Area is:
can contain: (2)
100'
Recommended Advanced Warning Sign Spaceing: Urban (low speed)
350'
Recommended Advanced Warning Sign Spaceing: urban (high speed)
500'
Recommended Advanced Warning Sign Spaceing: Rural
1000', 1500', and 2640'
Recommended Advanced Warning Sign Spaceing: freeways and expressways (3)
