Traffic Control Devices and Materials
Devices and materials
TTC devices include warning and guide signs, channelizing devices (cones, drums, tubular markers), barricades, temporary barriers, crash attenuators, temporary pavement markings, flagger paddles, and lighting. Devices must be visible, stable, crashworthy when required, and correct for the application. Warning signs for TTC generally use an orange background with black legend; fluorescent pink is reserved for incident management. Signs must be legible, properly mounted, and not obscured by equipment.
Know the difference between channelizing and positive protection. Cones and drums guide traffic; barriers and crash attenuators provide positive protection. A barricade is a channelizing device, not a barrier. Drums should be ballasted so they stay upright but still yield when struck. Device spacing and taper length increase with speed, and larger devices with greater target value are preferred as speed, volume, and duration increase.
Traps: assuming cones provide worker protection; using a permanent yellow warning sign where orange TTC signing is required; placing signs too low or behind vegetation; failing to ballast drums; and using damaged or nonretroreflective devices. Sign supports must be crashworthy or shielded.
Worked example: a 55 mph lane closure needs a merging taper with drums or other high-visibility channelizing devices, adequate advance warning, and positive protection if workers are exposed close to traffic. Cones alone may be acceptable only for low-speed, short-duration, low-exposure work.
Rule of thumb: as speed, volume, duration, and worker exposure increase, use devices with larger visual target, more spacing, and more positive protection.