Tunnel Vijenac, also known as Tunnel "1. Mart" (meaning Tunnel of March 1st), is a twin-tube tunnel on the A1 motorway in Bosnia and Herzegovina, with a total length of approximately three kilometers. It serves as a vital link within the Pan-European Corridor Vc, connecting Kakanj near Bilješevo to Zenica. The tunnel's construction started in 2010 and was completed in 2016, making it a relatively recent addition to the Bosnian motorway network. Its twin tubes, each measuring 2,962 meters in length, accommodate two traffic lanes per tube. Additionally, nine emergency pedestrian passages was built in to ensure safe evacuation in case of emergencies. Aslo, two transverse links provide access for rescue and maintenance vehicles.