“Access routes affect emergency rescue or and have effects on implementing fire suppression tactics from any potential location on the structure. Approved fire apparatus access roads shall be provided for every facility, building or portion of a building hereafter constructed or moved into. Where two or more access roads are required, they shall be placed at approved locations.”
Reference: http://www.cityofvancouver.us/fire/page/development-standards-fire-department-emergency-access
In a broader perspective, access is not always land based, but may involve water access for remove facilities requiring boats and potentially helicopters.