What is the term for the portion of the right of way at grade level for pedestrian use?

The correct term for the portion of the right of way at grade level designated for pedestrian use is "sidewalk." This area is specifically designed for pedestrians to walk safely alongside roadways, separate from vehicular traffic. Sidewalks are crucial for providing a safe passage for pedestrians, allowing them to navigate urban environments without having to share the designated traffic lanes with vehicles.

In terms of other definitions, a crosswalk refers to the marked path across a road where pedestrians may cross, which may or may not be adjacent to sidewalks. A carriageway typically refers to the part of the road used for vehicles, rather than pedestrians. Meanwhile, a pedestrian access-way describes pathways for pedestrians but doesn't specifically denote the typical infrastructure meant for walking along streets. Thus, the most accurate choice that aligns with the description of a pedestrian-use area at grade level is indeed the sidewalk.