Which of the following are effective Warning Devices for alerting motorists of an upcoming work area?

Warning devices play a crucial role in ensuring the safety of both motorists and workers in a construction zone. Each of the devices listed serves a specific purpose in alerting drivers to an upcoming work area, thus contributing to safer driving conditions.

Rumble strips are designed to produce noise and vibration when driven over, effectively capturing the attention of drivers. When placed before a work zone, they can alert motorists to reduce their speed and prepare to navigate the area with caution.

Message boards are electronic signs that can display various messages, including warnings about roadwork, detours, and other pertinent information. Their flexibility allows for real-time updates, which is valuable in communicating changing conditions to drivers.

Flashers are warning lights that can be activated to attract attention to a work zone. They are particularly useful in low-visibility situations, serving to enhance the visibility of the work area and alerting motorists to proceed with caution.

When combined, these devices create a comprehensive warning system that effectively signals to motorists the presence of upcoming work areas, significantly enhancing safety in those zones. Thus, all the mentioned devices are effective in alerting drivers and play integral roles in work zone traffic control.