My reason for the observation that the triangular pillars were unusual were based solely on looking at several pages of google images where I couldn't find any images of other bridges with similar triangular pillars.
Yes, that was the point I was trying to convey in my response to Geoff-E. Although it isn't unusual to see triangular shaped cutwaters at water level, and on low-height bridges like Geddington it isn't unusual to see them extend to parapet height. But the subject of the painting is a high-level bridge which means considerable extra material and effort went in to building these structures to full-height, which is not something you see that often.
The closest I've found in design terms is the Loyn Bridge over the River Lune.
https://en.wikipedia.org/wiki/Loyn_BridgeHowever the backdrop of the Loyn Bridge is completely wrong for the bridge in the picture. In addition the area the 'family' are walking in is heavily wooded in the Loyn Bridge location. Although the far river bank does look a bit similar and there is even a tree (possibly Ash?) standing on its own like the one in the painting. (This would be on the basis of viewing the bridge from the south).
One thing I wasn't sure about the painting bridge is whether it has two spans, or if a third is hidden from view by the trees/bushes on the right-hand side of the picture. The third span possibly being shorter than the other two based on the line of the riverbank.
That was one of the things which made me take a good look at the Loyn Bridge - it to has two roughly equal spans with a third shorter span on the eastern side of the river.
If no other location for painting turns up then my guess would be the artist has taken the Loyn Bridge (not a million miles from Silverdale) as inspiration and planted it in a more interesting backdrop.
