Septemvri–Velingrad This first part is 39 km long. It starts at Septemvri, where it meets the
standard-gauge railway line
Sofia–
Plovdiv. After almost straight 6 km long section in the plain, the route reaches station Varvara, the former
junction with the removed
branch to Pazardzhik. Then the route passes the river
Chepinska reka (also known as Elidere) and the road to Velingrad onto a steel bridge and continues on the left (eastern) bank of the river. As a part of the road widening work, some time between 2013 and 2016 the bridge was replaced with a new one. Along the gorge, the line passes Marko Nikolov (ex Mineral baths),
Tsepina (ex
Dorkovo) stops, the river again and the road at manually operated
level crossing, to reach station Dolene, where it continues in the opposite direction on the other side of the valley, climbing 246 m level displacement to
drainage divide Chukata and station
Kostandovo ( 801 m
AMSL) in 10.9 km. Here is the maximum
slope of the route at 32 ‰. After passing this station, the route descends to Velingrad valley. In the beginning there are also stops Milevi skali at km 17.5 between Tsepina and Dolene and Dryanov dol between Dolene and Kostandovo. In the period of heavy traffic in 60s and 70s, Dryanov dol is extended with
passing loop and becomes a station, but then it is completely closed, together with Milevi skali. Tsepina also had been station with
passing loop and
sidings, removed in 2003. All 10
tunnels on this part of the railway are between Marko Nikolov and Dolene. In April 1928 as a result of the
Chirpan earthquake (M6.8), a huge amount of rocks collapses over the track at km 11.7. A new tunnel Nr 2 is constructed to avoid the small radius curves of the temporary track around the collapse. The abandoned old tunnel is still existing next to the new one. It is visible from the road, but not from the train. The open track between tunnels Nr 3, 4, 5, 6, 7, 8 is now covered to prevent another rock collapses on the route.
Velingrad–Yakoruda This is the hardest section of Septemvri–Dobrinishte railway. It is 45 km long and all four
spirals, 25 remaining tunnels and the highest railway station on the Balkans are here. Beginning from Velingrad, through Velingrad south stop, the line starts to climb along the right side of river Ablanitsa, heading Ostrets stop and station
Cvetino. A few kilometers after Cvetino, the route turns to the right through the valley of the small river Lyuta reka, reaching the former station, now minor stop Sveta Petka. There the route enters the
Avramovo Saddle between the Rhodope Mountains and Rila and starts climbing 224 m in 9.8 km distance to station
Avramovo, which is the highest railway station on the Balkans at 1267 m above sea level. Just after Tunnel Nr 16, the track passes a stone
arch bridge over the river and begins its four-level way on the north side of the valley through 16 tunnels, two
spirals and one 180° turn. The line passes under itself two times in tunnels Nr 18 and 24. In this section, the train changes its traveling direction 6 times. The average incline is 30 ‰. The climbing ends at station Avramovo just after tunnel Nr 32, which is the longest one – 315 m. This highest point is followed by steep and long descent in the valley of river Dreshtenets. After the
Smolevo stop, the line turns at the third spiral, passing under itself in tunnel Nr 34. Just after the spiral, the route overpasses the river and the road on a stone
arch viaduct, followed by the fourth spiral around a natural hill, where is the last tunnel Nr 35. Reaching
Cherna Mesta stop, the track continues to
Yakoruda through the valley of river
Mesta. Since 2020 there is a new stop Yakoruda mineral baths. Sveta Petka and Cherna Mesta are former stations, which have had
passing loops and
sidings. Between Sveta Petka and Avramovo there is also a closed stop for the nearby village
Pashovo.
Yakoruda–Dobrinishte The last part of the railway has much better parameters, because most of the route is traced for
standard-gauge railway, which had been planned to replace the narrow-gauge track in future. After stops
Yurukovo and
Dagonovo, the line passes station
Belitsa and continues to General Kovachev stop, where it leaves the valley of river Mesta and heading
Razlog through the valley of smaller river, named Iztok. In his end, the track passes the longest bridge over the river – 58 m long stone viaduct with four arches. It is followed by Guliyna banya stop and after this point the railway continues in the Razlog plain and reaches its final station
Dobrinishte through Razlog and
Bansko. In Razlog there had been a small branch, serving some industry near the town. It is source of the last freight traffic until 2003, when closed and removed. ==Traffic and rolling stock==