Final answer:
The highway transportation system comprises people, vehicles, and roadways, which include pedestrians, drivers, various forms of transportation, and the network of roads and highways.
Step-by-step explanation:
The parts of the highway transportation system (HTS) can be categorized as D. People, vehicles, and roadways. This comprehensive system is designed to ensure the smooth transport of people and goods.
People are the users of the HTS, which includes pedestrians, cyclists, and drivers who navigate the system on a daily basis. Vehicles represent various modes of transport, such as cars, trucks, and bicycles, which are essential to the mobility within the HTS. Finally, roadways make up the physical network that includes roads, streets, and highways, which facilitate the movement of vehicles and people.
The development of the interstate highway system was a significant project that drastically improved the ability to travel by automobile across the nation. Ironically, the rise of the HTS also led to challenges in urban planning, such as the need for large-scale parking and accommodating increasing numbers of vehicles without negatively impacting the natural beauty of landscapes.