What is the suggested advanced warning sign spacing for freeway or expressway environments?

In freeway or expressway environments, advanced warning signs are crucial for providing drivers with sufficient time to prepare for changes in road conditions, construction activities, or other hazards. The correct answer, which is 2640 feet, aligns with the guidelines established by traffic management and safety authorities that recommend greater spacing for advanced warning signs in high-speed areas.

This spacing allows drivers to process the information presented on the signs and react appropriately, ensuring that they have adequate time to adjust their speed or maneuver safely as they approach the area where the warning is applicable.

The other options do not meet the recommended distance for effective communication in these high-speed environments, which tend to require more distance due to the higher traveling speeds of vehicles. A spacing of 2000 feet, 1500 feet, or even 1000 feet would not provide the same level of advanced warning and reaction time for drivers, potentially leading to dangerous situations on fast-moving thoroughfares. Thus, the choice of 2640 feet is justified for maximizing safety and driver awareness on freeways and expressways.