The Montana-Sofia expressway, with a tunnel under the Petrohan Pass, is a critical link in the national and European transport networks. Currently, transit times on the Sofia-Petrohan-Montana route and towards Lom on the Danube are significantly longer due to the difficult passage through Petrohan. In winter, traffic restrictions are often imposed due to the mountainous terrain and harsh weather conditions, increasing the burden on alternative routes.

Plans for such an expressway have existed since the late 1980s, but due to the presence of protected areas and sites along the proposed routes, previous projects were cancelled