Illuminated Sign Boards
The Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) is a set of widely implemented guidelines, which governs the installation, application and maintenance of equipment used in US-based roadways.
Published by the Department of Transportation’s Federal Highway Administration (FHWA) and frequently referenced by OSHA, the standards provide best practices for using illuminated sign boards in work zones during roadside construction. The recommendations provided by MUTCD are effective in reducing light glare and improving detection of traffic signals.
Arrow Board Classifications and Sizes
Also known as “chevron signs,” arrow boards are used to notify drivers about the presence of work zones and road closures. These accessories vary in size, depending on the needs of the construction project and type of road. For low-speed roadways, small or medium-sized units are recommended, while high-speed locations require the use of large arrow boards for timely detection at far distances.
The MUTCD sets forth the following categories for arrow boards, based on size: Type A (48″ x 24″), Type B (60” x 30”), Type C (48” x 96”) and Type D (no size specification – only requirement is arrow size: 48” x 24”). Type D arrow boards are suitable for mounting on vehicles inside construction work zones, such as a paver or an industrial sweeper.
Operating Modes and Dimming
The robust sign boards support several operating modes for managing road conditions. For tasks performed at the shoulder and when lane closure is not required, caution mode is typically applied.
Like all lighting systems for roadside construction, blinding must be avoided at all costs. To reduce such occurrences, the MUTCD advises the utilization of a dimmer for arrow boards. Regulators recommend 50-percent dimming capabilities (based on the unit’s daytime settings) for nighttime conditions, as well as the use of light sensors for automated dimming controls.
For more information about traffic lighting systems, please visit Larson Electronics.