The Roman arch prevented pressure completely, trying to keep each of the masonry in compression, in the keystone into the piers. Stone in compression has good power, and the Romans designed large arched bridges and aqueducts in large figures. Extending their arch right into a tunnel, they invented the barrel https://vymaps.com/US/West-Hills-Masonry-VN23008/?id_new=91f028d46d98c5b158f38e36720f8a1f