The bridge is a Protected Structure. it was heavily repaired/tarted-up about ten years ago.
The structure was originally three arched [east arch now absorbed into the re-aligned bank] and it appears to be the same structure as the one depicted in elevation on a 'Map of the Phoenix Deere Park' dated 1671. Some people think it may be contemporary with Sydney's rebuilding of the six arch bridge over the Liffey at Islandbridge in the 1570s, being situated on the same route into the city from the west.
The reference for the 1671 map is NLI [Manuscript Library] 17 G 48
There's a good, early 20th century, photograph of the bridge [all three arches] from the north east in Seosamh O'Broin's history of 'Inchicore, Kilmainham and District' published in1999, a plundered copy of which was posted in these parts a few years ago, but on which thread god only knows.