During rush hours, what is the function of some traffic signals at expressway entrances?

Traffic signals at expressway entrances during rush hours primarily serve to control vehicle entry into the expressway. This function is crucial for managing traffic flow, especially during peak travel times when the volume of vehicles can exceed the expressway's capacity. By regulating the number of vehicles that enter the expressway, these signals help to prevent congestion, reduce the likelihood of collisions, and improve overall safety on the roadway.

The signals may allow vehicles to enter the expressway in a staggered manner, reducing the potential for backups and ensuring a smoother transition from the entrance ramp onto the highway. This method helps maintain efficient traffic flow and minimizes the risk of accidents that can occur when too many vehicles enter at once.