Flagger illumination during nighttime construction and maintenance operations

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 20feet 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 10feet 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 10feet 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.