Khojasan depot

"Khojasan" depot of the Purple Line has been commissioned. Every line has its own depot. Fifty-five years after the inauguration of the Baku Metro, its second depot has been launched. The entire infrastructure project of the depot, covering an area of 24.28 hectares, is planned to be constructed in three phases. Currently, areas crucial for the existing infrastructure covering four stations and tunnels of the line have been established. The work for the next two phases will be conducted as new stations and tunnels of the line are constructed, in accordance with the demand.

It's noteworthy that over the past years, the "Narimanov" electric depot has been serving trains operating on the Red and Green lines. Organizational matters related to the technical condition, inspection, and repair of trains operating on the Purple Line, commissioned in 2016, have also been carried out at the "Narimanov" electric depot.
However, according to operational requirements of the metro system, each line should have its own depot. Therefore, the commissioning of the "Khojasan" electric depot will enable all organizational and service operations on the Purple Line to be independently provided.
Line Access Tunnels - The Next Success in Metro Construction
The construction of the depot began with the excavation of tunnels connecting it to the "Bus Station," the first station of the Purple Line. The work on tunnels, 1,112 and 1,235 meters long, was carried out under the densely populated area of Bilajari, in challenging hydrogeological conditions. The area was characterized by unstable soil layers and rich groundwater sources. The absence of sewage lines in the residential area complicated the situation further, as infiltrating wastewater hindered the diggers' work. Additionally, since the tunnels passed under the railway mainline and crucial engineering communication lines, special preventive measures were taken to avoid any unforeseen accidents. Experienced, professional specialists were engaged in the work, strictly adhering to labor protection and safety techniques. Consequently, the tunnel excavation was safely conducted, marking another bright success in Baku's metro construction history.

The tunneling work was carried out using shield driving, completing one tunnel in 2019 and the other in 2020. Both tunnel tracks were built on reinforced concrete blocks produced by the Baku Metro's own manufacturing facility, rather than on wooden sleepers. This significantly saved financial resources, preventing the outflow of currency abroad, and creating more favorable operating conditions and environments with the application of the latest technologies without dependency on foreign manufacturers. Maintenance and service of this type of road infrastructure are easier and more cost-efficient.

First Phase Main Construction Works
After completing the relevant relocation works, retaining walls were constructed to protect the southern part of the depot area from landslides. In the final phase of the work, besides systems ensuring the depot area's safety, walls facing the Baku circular road featured stands reflecting the care and attention of the state, the 55-year history of the Baku Metro, the unparalleled contribution of the national leader Heydar Aliyev to the metro, and projects aimed at infrastructure and human resources over the last five years. Landscaping was carried out, greenery was planted, and trees were sown considering the soil properties of the area. It's worth mentioning that green spaces were also arranged in the depot area, and corners and a green belt along the slope across the portal area with over 2000 trees and bushes were created. This not only improves the ecological environment of the surrounding area but also further strengthens the soil stability of the slope.

As for infrastructure facilities, all service areas for the first phase have been commissioned. This includes the dispatcher control center for train movement, maneuvering organization, and process supervision, a 35 kV electric substation, a temporary service and inspection area for passenger trains serving as a depot for utility trains, a cargo terminal, depot tracks and the branch connecting them to the Azerbaijan railway mainline, two drinking water reservoirs each with a capacity of 240 cubic meters, two fire water reservoirs each holding 500 cubic meters, a 201-meter-long power cable collector, and most importantly, Baku Metro's 2nd above-ground station, etc.

Depot Tracks
The total length of the depot tracks is 11,857 km. In the first phase, including the test track, 4,279 km of movement rails built on 5298 reinforced concrete sleepers is directed to the motor depot, cargo terminal, test track, transition tracks, Azerbaijan railway mainline, and "Khojasan" station by 33 switch devices. The total length of the branch leading to the Azerbaijan railways is 1140 meters. During construction, the rails were transported to the depot via the branch separated from the main railway. In the future, cargoes and new wagons for the Purple Line will be delivered to the depot in this manner. It's reminded that five years ago, on the eve of the opening of the Purple Line, this path did not exist, so trains were lowered to the line from the "Bus Station" branch through special planning work. The distinctive feature of the park tracks is the safety barriers for the contact rails.

Movement, Signaling, and Communication Systems Organization
The installation of the signaling and telecommunication system of the "Khojasan" depot was realized based on two important contract documents signed between "Baku Metro" JSC and "Thales International" company during the visit of the First Vice-President of the Republic of Azerbaijan, Mrs. Mehriban Aliyeva, to the French Republic on March 11-12, 2019, within the framework of the signing ceremony of Azerbaijan-France documents. One document was related to the creation of the Operation Control Center for the Purple Line dispatcher center, and the other to the realization of the signaling and telecommunication system of the "Khojasan" depot. This meant that along with the construction of the "Khojasan" depot, the main activity's supporting system was also determined.

The organization of train movement is based on the most modern technologies of signaling, centralization, and communication systems. Cooperation with "Thales" in organizing the operation and management of the station will enable the application of modern SCADA and CBTC systems, microprocessor centralization systems, and "wheel counter" equipment, enhancing the safety level of movement and applying a new model of dispatcher management. For the initial phase of the depot's operation, 23 tower signals, 19 dwarf signals, 69 "wheel counters" were installed, 33 switch devices were provided with actuators, and 25,000 meters of signal cable were laid. Two of the signals - the entrance-exit and branch signals - belong to the "Khojasan" station.

Based on a unique project model applied in aviation, the dispatcher control center building is one of the depot's most crucial facilities. The five-story circular building is an analogue of a similar purpose-built facility recently commissioned at the "Narimanov" depot. The highest floor of the multifunctional centralization center, equipped with modern devices, allows the centralization duty officer to observe train movement both through modern systems in front and visually enhanced by a modern video surveillance system. This optimizes security and safety measures based on the latest technologies in the depot area. Other floors of the building house signaling and communication equipment, microprocessor centralization and relay racks, an automated workstation for electrical mechanics, a video surveillance center, and areas created to meet the social and domestic needs of the staff according to new requirements and standards.

Electric Substation
The electric substation of the depot is capable of meeting the energy needs of not only the first phase but all phases of construction-related facilities. The substation, providing energy to all electric consumers of the depot, including the dispatcher centralization center, motor depot, "Khojasan" station, pump stations, cargo terminal, and other utility facilities, has a nominal power of 11.920 kW and a voltage of 35 kV. The internal cable network of the substation consists of 10,000 meters of entry and 18,550 meters of exit power cables. The length of the 825 V cable network is 11,000 meters.
The energy supply scheme of the new depot differs from that of the "Narimanov" depot. There are two distribution devices for 825 V here. One supplies the park tracks, and the other provides traction power to trains moving between "Khojasan" and "Bus Station." For the full operation period of the substation, two 1000 kVA and four 630 kVA power units, as well as four 1600 kVA power units, have been installed. All equipment is prepared based on modern technologies.

Most Important Service Facilities
The utility train depot (motor depot) will be used as a repair, inspection, and storage facility for passenger trains in the first phase. Since only six train compositions are considered to meet the needs of the line at the current stage, the repair and inspection facilities for wagons will be temporarily conducted in the motor depot until the construction of the main repair and inspection facilities for passenger trains in the second phase. For this purpose, repair-inspection pits have been constructed in the area. The area is equipped with necessary equipment for the repair of wagons and, in the future, utility trains. Bridge cranes and other devices will be used to minimize manual labor. A normal work and living environment, labor safety and security, and ecological conditions have been established for the workforce.

The cargo terminal (service loading-unloading point) is intended for the accumulation of goods brought to and from the depot area. Construction materials for tunnel works – sand, gravel, cement, etc. – are collected here, and waste from the tunnels is transported to the cargo yard by utility trains. Two bridge cranes have been installed here. Until the construction of the main repair and inspection facility for passenger trains in the second phase, the inspection and repair of the platforms of motor and utility trains will be conducted in the cargo yard. For this purpose, a 20-meter-long pit has been constructed, and all necessary conditions have been created.

Infrastructure Projects Supporting Depot Operation
Like the centralization center building and electric substation, many other infrastructure projects are calculated for the situation after all three phases. Therefore, all communication line works cover the entire area in accordance with the project. Cable collectors, sewage lines, and their potential carrying capacity cover the full scope of the project. Thus, only the construction of main infrastructure areas will be carried out in the second phase.

The depot features modern security, information-communication, communication, fire protection, lighting systems, and two boiler rooms. Areas equipped with modern devices have been allocated for vehicle parking. Both entry-control points are equipped with devices for automatic control-registration with service badges. Modern-type car parks have been created near them.