Many of the layouts are duplexes or triplexes. The remaining 4% are duplexes, triplexes, or quadruplexes. The remaining dwellings are roughly 28% duplexes (including triplexes and quadruplexes) and 21% single-family dwellings. These include cruciforms, intramolecular triplexes, and more. Those buildings that have a third storey are known as triplexes. The formation of PPRHs triplexes takes place at physiological pH. PPRHs provoke a strand displacement. The Erie Railroad scrapped their Triplexes from 1929, 1931, and 1933. The brick triplexes on Overdale are already gone, unprotested, replaced by more parking space.