An alternative route: why closure of the Nizami–28 May section should be postponed

The planned separation of the Baku Metro’s Red and Green lines is technically necessary. However, the proposed 11-month closure of the Nizami–28 May section threatens to cause large-scale transport disruption in the centre of the capital. As an alternative, the closure of this critical section could be postponed and the project carried out in stages, beginning with construction of the Darnagul–Bakmil-2–Ulduz link. This would reduce train intervals, preserve established passenger flows and allow the integration of underground infrastructure to be completed without undue haste.

The separation of the Baku Metro’s Green and Red lines, due to begin on August 15, is a long-overdue and technically justified undertaking. In the current configuration, the merger of the two branches creates a bottleneck that forces trains to run at longer intervals, particularly on the 28 May–Darnagul section. A fully developed interchange at 28 May station would allow timetables on the two lines to be regulated independently, significantly reduce intervals and improve the long-term safety of passenger services.

Despite the project’s strategic importance, however, the chosen implementation scenario would place an enormous burden on the city’s infrastructure. Closing the section between Nizami and 28 May stations for 11 months would sever the key east–west corridor, Hazi Aslanov–Darnagul, which has historically carried the capital’s main passenger flow. The announced replacement buses cannot physically fill the gap because the carrying capacity of a single metro train is more than 20 times that of an articulated bus. As a result, tens of thousands of passengers who can no longer make their usual direct metro journey would be forced to switch to surface public transport or private cars.

The temporary closure of the Nizami–28 May section risks overloading the road network and triggering systemic transport paralysis in central Baku. Separating the metro lines is unquestionably necessary, but the cost of doing so should not bring life above ground to a halt.

The most effective option would therefore be to postpone separation of the Red and Green lines near 28 May and Jafar Jabbarli stations and create the Green Ring in stages, with two interchanges: first at Bakmil and only then at 28 May.

The first stage would involve construction of the 3-kilometre Darnagul–Bakmil-2–Ulduz section.

What would this achieve?

The project proposes building a new northern interchange station, Bakmil-2, beneath the existing above-ground Bakmil station.

Construction of the Darnagul–Bakmil-2–Ulduz section would connect the eastern Hazi Aslanov–Ulduz segment of the Red Line with the Darnagul–28 May segment of the Green Line. At present, the Green Line ends at 28 May and merges there with the Red Line; after the lines are separated, the Green Line would bypass 28 May, continue to Jafar Jabbarli and then to Khatai. The link would allow direct, no-transfer services from Hazi Aslanov to 28 May and, in the future, to the parallel Jafar Jabbarli station. Bakmil and Bakmil-2 would form the northern interchange between the Red and Green lines.

Under this option, the Red Line would be shortened to the Bakmil–Icharishahar route, returning it to its original 1967 configuration, when the metro’s first Red Line section entered service.

The project would be advantageous both because it would reroute and shorten the main train service, cutting intervals to 1.5–2 minutes, and because it would optimise passenger routes and journey times. About two-thirds of passenger traffic is concentrated on the sections that would form the future Green Ring, and most passengers travel from one end of the city to the other. The proposed configuration would therefore reduce journey times between the busiest stations in the east — Koroglu, Ahmadli, Khalqlar Dostlugu, Gara Garayev and Neftchilar — and those in the west — 20 January, Elmlar Akademiyasi and Memar Ajami, which also provides an interchange with the Purple Line.

Passengers travelling towards the city centre along the Green semi-ring from Hazi Aslanov would meanwhile be able to transfer to the Red Line by leaving the train at Bakmil-2 and walking to Bakmil. They would no longer need to travel through the city centre and place further pressure on the already congested 28 May interchange. Unlike the old 28 May station, built in the 1960s, the new Bakmil/Bakmil-2 northern interchange could be designed to be much more spacious and capacious, as the entire site beneath which it would be built belongs to the metro.

Technically, construction of the Darnagul–Bakmil-2–Ulduz section would proceed as follows: the section between Darnagul and Bakmil-2 would be built using the cut-and-cover method; the shallow Bakmil-2 northern interchange station would be constructed; and a short stretch from the new station to a junction with the existing Nariman Narimanov–Ulduz section would also be built by cut-and-cover.

Given the shallow depth of the tunnels in this area and an artificial-intelligence estimate that one kilometre of metro built by cut-and-cover would cost an average of $40 million to $120 million, or 70 million to 200 million manats per kilometre including a station complex, the project could be implemented at a comparatively modest cost of about 200 million to 600 million manats. This method is roughly 25–35 percent cheaper and one and a half times faster than closed, deep-level construction, and the work could take about 1–1.5 years. Funding could be found within the 2025–2030 State Programme for the Development of Baku’s Transport Infrastructure, whose total financing amounts to about 4.2 billion manats, or around $2.5 billion.

Once the Darnagul–Bakmil-2–Ulduz section is complete, the second stage could begin: separating the Red and Green lines near 28 May station and suspending train services on the Nizami–28 May section.

This would avoid or substantially reduce excessive pressure on surface transport because connectivity between the metro lines would be maintained. The Green Line would operate temporarily on the Hazi Aslanov–Nizami section, while the Red Line would run between Bakmil and Icharishahar.

Completion of the first stage would also allow new Green Line tunnels towards Jafar Jabbarli station to be built without haste and without the pressure of a rigid 11-month deadline. The work would have to be carried out amid a high groundwater table and unstable soils around 28 May, creating the risk of unforeseen complications.

In addition, connecting new tunnels to 60-year-old underground infrastructure requires exceptional precision and periodic reinforcement of tunnel vaults, which may also demand more time. Completing the tunnel excavation is only part of the task: installing new automation, power-supply and signalling systems, and testing trains under the new operating regime, often takes longer than the tunnelling itself.

After this work is completed, the Green Line would form a semi-ring running from Hazi Aslanov to Khatai. Passengers would be able to transfer from the Green semi-ring to the Red Line at two points: the Bakmil-2/Bakmil interchange and the Jafar Jabbarli/28 May interchange.

In the third stage, the Green Line could be extended through the Nizami and Khatai districts to Hazi Aslanov station. It would then become a full ring, fundamentally addressing the capital’s main public-transport problems.

The proposed phased scenario, prioritising construction of the Darnagul–Bakmil-2–Ulduz section, would accomplish the strategic task of separating the metro lines without risking transport paralysis in central Baku. It would preserve connectivity along the city’s main passenger corridor during complex underground works and give engineers the time needed to integrate the infrastructure safely. In the long term, this would become the first practical step towards a full ring line that would substantially improve the reliability and carrying capacity of the capital’s entire public-transport system.