The writer of this song, Frank O'Donovan (1900-74), was a Dublin born actor, singer and song-writer who was well known in Ireland due to his being in Ireland's first TV soap. The probability is that he visited one or more of the Raheens in his touring in Ireland. There was someone from one of the Raheens killed in the famous Upton ambush but there is no evidence of an O'Donovan killed in any ambush. O'Donovan also wrote a song called "The Little White Cross" which also used the roadside white cross theme. Given that it was written by O'Donovan in 1940 the likelihood is that "The Road" is a commercial composition rather than reflecting personal or family experiences.
O'Donovan himself performs the lyrics of the song as given by Alice above, with a few minor alterations such as "auld" instead of "old" in some places.