The Corridor X is one of the pan-European corridors. It runs between Salzburg in Austria and Thessaloniki in Greece. The corridor passes through Austria, Slovenia, Croatia, Serbia, Macedonia and Greece. It has four branches: Xa, Xb, Xc and Xd.
The European Bank for Reconstruction and Development has given loans to support infrastructure improvements along Corridor X.
X: Salzburg - Ljubljana - Zagreb - Belgrade - Niš - Skopje - Veles - Thessaloniki.
Branch A (Corridor Xa)
Main article: Corridor Xa
Corridor Xa runs between Graz, Austria and Zagreb, Croatia through three countries: Croatia, Slovenia and Austria.
Branch C (Corridor Xc)
Corridor Xc follows the route Niš - Sofia - Plovdiv - Edirne - Istanbul.
The road in Serbia from Niš to the Bulgarian border near Dimitrovgrad currently is being upgraded to a motorway standard. Construction works are expected to be completed in all sections in 2017.
In Bulgaria some 31 km of Kalotina motorway from Kalotina to Sofia were tendered in 2012. Currently transit traffic has to pass via Sofia ring road, but a new bypass Northern Speed Tangent was tendered in 2012 and is expected to be completed in 2015. Trakia motorway runs from Sofia to Chirpan, where Maritsa motorway, when completed in 2014, will branch off to Turkey.
In Turkey motorway passes near Edirne to Istanbul.