Final answer:
A low ground railroad crossing is a level junction between a railway and a road without any separation in height, generally marked by signs and signals.
Step-by-step explanation:
A low ground rail road crossing is typically a level crossing where a railway line intersects with a road or path at the same level, as opposed to an overpass or underpass where the two cross at different heights. Such crossings can be found in rural or urban areas and are identified by their warning signs, lights, and sometimes barriers to prevent accidents when a train is approaching. From the provided references, it's clear that the concept of a railroad and its crossings is not the main focus, but rather a setting for various narratives involving trains and their adjacent environments.
These references talk about military outposts near railroad bridges, wartime orders regarding the sabotage of railway infrastructure, a station on the muddy shore of San Francisco Bay, strategies in military expeditions described in classical texts, poetic expressions of train crossings, and the description of a landscape around a town with railroad tracks.