ATSSA Traffic Control Supervisor Re-certification (missing some basics) Verified Answers 2025

Formula for Min. taper length - L=(WS²)/60 for 40MPH or less, L=WS for 45MPH or more Speed used in formulas should be - The off peak 85th percentile. Which is the speed at or below which 85% of vehicles travel operating speed in free flow conditions Distance of L for 25 MPH with 12' Lane width - 125' Distance of L for 35 MPH with 12' Lane width - 245' Distance of L for 45 MPH with 12' Lane width - 540' Distance of L for 55 MPH with 12' Lane width - 660' Distance of L for 65 MPH 12' Lane width - 780' Merging Taper Length - L Minimum Shifting Taper Length - 1/2 L Minimum Shoulder Taper Length - 1/3 L Minimum One-Lane, Two-Way Taper (Flagger taper) Length and number of devices - 50'-100' regardless of speed 6 devices 10'-20' apart Downstream taper Length - 50'-100' per lane Tangent distance (between tapers) - 2L Tangent distance before shifting taper - 1/2L Activity Area Sub-components (3) - Buffer Space Work Space Traffic Space Longitudinal Buffer Space - 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 Termination Area is: can contain: (2) - 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 Recommended Advanced Warning Sign Spaceing: Urban (low speed) - 100' Recommended Advanced Warning Sign Spaceing: urban (high speed) - 350' Recommended Advanced Warning Sign Spaceing: Rural - 500' Recommended Advanced Warning Sign Spaceing: freeways and expressways (3) - 1000', 1500', and 2640' Arrow board visibility distance by design: night time dimming: location: - 1 Mile 50% shoulder at beginning of taper if possible, if not, as close to beginning as possible inside taper.