Which of the following measures can reduce the impact of highway noise?

The chosen answer encompasses a comprehensive approach to reducing highway noise, recognizing that multiple strategies can be effective in addressing this environmental issue.

Each measure plays a distinct and valuable role. Setting lower speed limits for highways can significantly decrease noise levels since noise generated by vehicles often increases with speed. Slower-moving vehicles create less friction and can lead to a quieter travel experience for nearby residents.

Establishing alternate truck routes is another practical solution. By rerouting heavy trucks away from residential areas, the overall noise exposure for those communities can be minimized, which is particularly important since larger vehicles typically produce more noise than smaller passenger cars.

Enclosure of highways through residential areas, such as by constructing noise barriers or sound walls, directly interrupts the transmission of sound from the highway to the surrounding neighborhoods. These structures can absorb or deflect sound waves, effectively reducing the noise that reaches homes and schools located nearby.

Thus, the combination of these approaches recognizes that a multifaceted strategy is often the most effective method for mitigating highway noise, making the answer "All of the above" the most appropriate choice for this question.