Flagger Illumination during Nighttime Construction and Maintenance Operations

Document Type


Department or Administrative Unit

Engineering Technologies, Safety, and Construction

Publication Date



Ensuring the safety of flaggers, motorists, and workers is the primary consideration for flagging operations during nighttime construction and maintenance. A research study was conducted to evaluate four different types of light equipment—a light tower, 12 V spotlight, 12 V high-intensity discharge (HID) floodlight, and balloon lights—with regards to their level of illumination and uniformity over the flagging area and on the flagger’s body. For each type of equipment, three input variables—lamp output, offset angle, and luminaire height—were varied to create a total of 44 different light equipment configurations. Each configuration was evaluated in terms of illumination, uniformity, and visibility in an urban/suburban setting. The study revealed that a light tower with 2,000 W output, 0° offset angle, and raised to a height of 20 feet was the highest ranked type of equipment. However, when ease of use, mobility, and cost were added as output measures, a 12 V spotlight with 0° offset angle and raised to a height of 10 feet received the highest ranking. Smaller light systems are easy to operate and transport, inexpensive, and more applicable for short-term flagging operations and for operations that need to be relocated frequently. Highly ranked configurations were typically those at 0° offset with luminaires elevated to 10 feet or higher. Configurations with higher luminaire heights and lamp outputs from 250 to 2,000 W may perform better depending on the roadway setting, duration of flagging operation, and amount of artificial background lighting.


This article was originally published in Journal of Construction Engineering and Management. The full-text article from the publisher can be found here.

Due to copyright restrictions, this article is not available for free download from ScholarWorks @ CWU.


Journal of Construction Engineering and Management