outer "rings" of compound arches overlaying the one forming the intrados, used in old English bridges since medieval times, are called "counter-arches" following the works of John Smeaton;
an arch that is built adjacent to another arch to oppose its forces or help stabilize it. The counter-arch can be used, for example, when constructing the flying buttress,
buttressing arches built between the opposing building facades over narrow streets of old cities;
in fortification, an arch built on the tops of counterforts behind the bastion walls intended to limit the scope of the potential wall breaching;
when a pier of the Old Westminster Bridge started sinking during the construction, Charles Labelye was forced to retrofit the bridge with open spandrels using the counter-arches springing off haunches of the two adjacent arches of the bridge thus relieving the pier.
The Enneüs Heerma Bridge showing the inverted counter arch in the middle
Murray, J.A.H. (1893). "Counter-arch". A New English Dictionary on Historical Principles: part 1. C-Comm (1893). Clarendon Press. Retrieved 2024-07-05.
Trautwine, J.C. (1874). "The Moseley Bridge". The Civil Engineer's Pocket-book: Of Mensuration, Trigonometry, Surveying, Hydraulics ... Etc. ... Claxton, Remsen & Haffelfinger. Retrieved 2024-07-05.