Articulated trucks towing a single trailer or two trailers (commonly known as "short doubles") with a maximum overall length of are referred to as "General access heavy vehicles" and are permitted in all areas, including metropolitan. B-doubles are limited to a maximum total weight of 62.5 tonnes and overall length of , or if they are fitted with approved FUPS (Front Underrun Protection System) devices. B-doubles may only operate on designated roads, which includes most highways and some major metropolitan roads. B-doubles are very common in all parts of Australia including state capitals and on major routes they outnumber single trailer configurations.