A designation is like a 'spot zoning' over a site or route in a district or city plan. This 'spot zoning' authorises the requiring authority's works or project on the site or route without the need for a subsequent land-use consent from the relevant council. Once the designation is put in place, the requiring authority may do anything in accordance with the designation, and the usual provisions of the district plan do not apply to the designated site.
A designation also places restrictions on what anyone other than the requiring authority can do on the designated land, without first getting the requiring authority's permission or necessary approvals from the territorial authority.