How are parallel taxiways and cross taxiways conventionally designated?

Parallel taxiways and cross taxiways are designated based on their relation to the runway because this system provides clarity for pilots and ground control regarding taxiing routes. Specifically, parallel taxiways run alongside the runway and are typically designated with a standard nomenclature that includes letters, while cross taxiways intersect with taxiways and are designated with a different set of identifiers. This method of designation ensures that everyone utilizing the airport's layout can easily understand and navigate the taxiway system in relation to the active runways, facilitating smoother operations and enhancing safety on the airport grounds.

The other choices do not reflect the standard practices for taxiway designation. While the terminal's relation could be relevant for certain operational aspects, it is not the primary method used for taxiway identification. Length and width, as well as surface material, are not factors considered for designation in the airport taxiway system, as these attributes do not impact the operational guidance provided to pilots. Designation based on the relationship to the runway is crucial for the orderly and safe movement of aircraft on the ground.