If your advertising campaign is targeting romanian high & middle class, you should consider the most crowded route linking Bucharest area and Valea Prahovei (Prahova Valley): DN1 Bucharest - Ploiesti - Brasov.
Regional GDP for Bucharest - Ilfov is the highest of Romanian economy (with GDP per capita 2.5 times higher than the national average).
AADF (Annual Average Daily Flow) for DN1 (National Road no.1) may vary from 40.000 to 53.000 vehicles from one road segment to another. This is the highest AADF for a Romanian major road. Another route with equivalent AADF is Bucharest - Pitesti (A1 Motorway) that links western region of Romania with Bucharest.
DN1 is the shortest route from Bucharest - Ilfov to Prahova Valley and the first week-end and holiday destination. Most holiday homes located on Prahova Valley are owned by Bucharest & Ilfov residents.
DN1 links Bucharest to northern and central region of Romania (Cluj, Mures, Bihor, Harghita, Covasna, Maramures, Brasov, Prahova), so it also routed business traffic for above cities.
Advertising signs - billboard sizes