What is the purpose of "louvers" on traffic signals?

Louvers on traffic signals are designed primarily to reduce the visibility of the light from certain angles, which helps to prevent confusion for drivers who are not in the intended line of sight. This selective visibility helps ensure that the signal is clearly seen by vehicles in specific lanes, thereby promoting safety and compliance with the traffic control system.

While the other options touch upon various aspects of signal visibility or performance, they don't accurately reflect the primary role of louvers. Enhancing color visibility and reducing glare are important, but these factors are more related to signal design features rather than the specific function of louvers. Additionally, allowing for better signal synchronization pertains to the timing and coordination of traffic lights, which is separate from the physical characteristics and operational purpose of louvers.