## 1 Introduction
The implications of these findings are substantial for transportation planning and operation, emphasizing the importance of considering multiple factors to improve the overall passenger experience. Vibrations and noise in metro trains originate from two sources: external factors, such as poor infrastructure maintenance causing wear and noise during train passage, and internal components of the metro vehicle itself. The first group includes issues like railway turnouts or curved lines in tunnels, contributing to increased noise both inside and outside the train. The second group involves vibrations and noise generated directly  
Figure 1: (**a**) Set of the newer type 81 series compared to the version with an old front wall, (**b**) Alstom Metropolis 98b, (**c**) Siemens Inspiro, and (**d**) Skoda Varsovia. by individual components within the metro vehicle. Key contributors to internal noise are the converter and inverter. The converter, audible even when the train is stationary, changes voltage from the third rail for electrical equipment, often operating at 110 V. The inverter controls voltage for acceleration and braking, noticeable in specific train models like Metropolis 98b. The pneumatic system, controlling brakes and doors, produces increased noise and vibrations, particularly evident in Russian-made trains. Wheelset axle issues, including failures, defects, and damage to bearings, also impact vibrations and noise in metro vehicles. Rail vehicle body vibrations are categorized into stiff and flexible modes, affecting ride comfort. Stiff modes, like bouncing and rolling, occur at around 1 Hz, while flexible modes, impacting human balance, occur in the 4 to 12 Hz range. Minimizing stiff modes' impact with springs and shock absorbers does not directly address flexible modes, which require distinct designs [9, 10, 11]. Modern lightweight bodies, while reducing weight, may compromise structural stiffness. Relying solely on rigid modes for comfort analysis might overlook critical phenomena, especially considering structural flexibility's impact on acceleration levels in the vehicle floor [12, 13]. Proper wagon design and second-stage suspension assembly selection are crucial to prevent excessive vibrations [14, 15, 16, 17, 18]. Noise and vibration levels are further influenced by the drive system and bogie running gear characteristics, contributing to the overall vibrocacoustic climate. This paper considers rail vehicles used in the Warsaw metro. In Table 1, basic parameters regarding the rolling stock construction are presented. In series 81 vehicles, each train wagon is driven. In Metropolis trains, wagons 1 and 6 have non-powered bogies; in Inspiro trains, bogies in wagons 2 and 5 are not powered; and in the latest Skoda trains, non-powered bogies are used in wagons 3 and 4. Additionally, only Inspiro trains use non-rotational bogies. The Warsaw metro uses ballast-less (concrete) and sleeper-less tracks. The concrete foundation (acts as a ballast) on the M1 line uses B25-class concrete, appropriately formed with channels. For part of the length, the rails are placed in the lagging. S60E1 and S49E1 rails are used along with a rail attachment node. Both parts are connected with anchor bolts, fixed (glued) in the concrete base using epoxy concrete. On the Kabaty-Wilanowska section, the track surface is fastened with a K-type fastening with a triple ring and a Lpa2 clamp.