Plain common sense screams out that those low parapets are not safe.
Railway authorities have always required the provision of higher parapets where roads cross the railway.
On bridges where cyclists and horse riders are required to ride immediately adjacent to bridge parapets, higher parapets are provided.
The north masonry facade of the causeway, capped by a parapet, was significantly more formal than the southern edge of the causeway, where the ballast feathered out.
There are at least two shallow depressions, just ventral to the dental parapet, that may represent nutritive foramina, but these are indistinct and their identification cannot be confirmed.
Pinnacles were added above the parapet level.
Thus, the masonry wall created by the causeway foundation and parapet would have been effective at retaining and diverting the southerly flow of stream discharge and rainfall runoff.
Evidently, this is a diverse collection, whose contributors rarely rise above the specialist parapet to venture general or comparative ideas.
