However, most of the situations listed here only apply to the oldest autovías, and mainly to the radial A-1 through A-6 plus the A-42 near their endpoints, which were the first to be twinned in the 60s into dual carriageways (with at-level intersections) and then were upgraded to limited-access freeways in the 70s-80s, keeping most of their old route unchanged except where the old national road ventured into towns. In those cases, the freeway would make a semi-loop called a "variante" around the town, leaving the old national road as the access between the freeway and the town.