The design of a road is based on planning and data collection showing kinds and amounts of __________ using the road.

The design of a road relies heavily on the planning and data collection related to traffic, as this encompasses not only the types of vehicles that will use the road but also their volumes, patterns, and the overall flow of movement. Understanding traffic dynamics is essential for engineers and planners to ensure that the road can accommodate current and future needs without congesting or compromising safety. By analyzing traffic data, planners can make informed decisions on aspects such as lane widths, traffic signals, signage, and road alignment, which all contribute to a road's efficiency and safety.

While vehicles and pedestrians are important components of traffic, they are more specific subsets. Infrastructure pertains to the broader context of the road system but does not focus on the specific patterns and behaviors of traffic flow necessary for effective road design. Hence, the term "traffic" best encapsulates the broad set of data required for comprehensive road design.