Arcades are usually free standing elements in gardens or parks, which is why we have classified them in the category of 'other constructions' -- object greening. Here you will find various construction and trellising options. Information in the sections on pergolas and canopies (galleries/awnings/'green roofs') may also be useful. Some arcades are joined to a building or connect two buildings, and sometimes they act as outdoor corridors/passageways. See "greening large structures" for some examples.
Archways and arcades can have angular or round roofs made of wood or metal. They are often built with forms like pergolas. Modern, basic components are round arches made of steel pipes which are anchored in the ground on both sides, strutted diagonally (braced at an angle) and connected to each other up top. There are kits available for such projects. In addition, wooden slats are installed, or a wire rope arrangement (similar to that used for a pergola) is added. How to green these structures? Take a look at the section on pergolas. The concept is pretty much the same.