## 3 Results and Discussion  
The critical position of the impactor (Figure 4) is given below, when its angular velocity \(\omega=0\) rad/s and the deformations reached the maximum value (577 mm) in 137 ms and 109,287 calculation cycles. It is suggested to analyze the bus body frame front part behavior in combination with the driver's position at different moments of impact:  
* t = 35-65 ms (Figure 5a,b)--deformations are observed only in the window frame of the windshield and the structure of the front part (86 mm max). There is no risk to the driver's legs;
* t = 100 ms (Figure 5c)--the lower part of the driver's legs is at risk--the pedal unit is clearly deformed, which carries the risk of injury. The maximum observed model displacement is 390 mm at that moment;
* t = 137 ms (Figure 5d)--under the influence of the impactor, maximum deformations of the front part were achieved (577 mm of the lower window still at the level of the driver's knees). The deformation of the structure indicates a possible injury risk to the lower limbs, pelvis, and hands of the driver (the steering column will definitely enter the residential space zone). To determine the level of damage to the driver, it is suggested to build a matrix of Y-deformations (Y is the longitudinal axis of the bus corresponding to the impact vector) at the control points #1-9 of the front body part relative to the driver's seat mounting points A and B (Figure 6). The maximum Y-deformation of the mounting points during the crash test is A = 1.1 mm and B = 37.8 mm. In fact, the Ansys \"Solution > Deformation\" tool means a change in the coordinate of the point position relative to the initial state (its displacement), but for the applicability of the presented methodology, it was decided to leave the original Ansys terms. Thus, to calculate the relative deformation of any of the nine selected points, it is necessary to subtract 1.1 mm (relative to point A) or 37.8 mm  
Figure 4: Front impact according to UNECE R29: (a) hidden impactor; (b) shown impactor. As is widely known, all UNECE safety rules are based on the analysis of accident statistics involving road vehicles, in particular buses, which is the subject of our research (low-entry and low-floor buses). Scientists analyze the conditions of live accidents and transfer them in the form of boundary conditions to the appropriate regulations, e.g., NCAP or R29 regarding the speed and energy of the collision, etc. As a result, there is a difference in the way the frontal impact test was performed: the bus hit the wall at high speed (NCAP) or the pendulum hit the front part of the fixed bus (R29). The difference between them lies in the perception of impact energy: in NCAP conditions, it is mainly the entire bus that deforms as opposed to the front part in the case of R29, but its deformation is much stronger--this results in more danger for the driver. Another characteristic feature is the time to reach the maximum deformations in the front part of the bus: in tests for compliance with the R29 regulations, this moment is reached earlier than according to NCAP (137 ms vs. 170-230 ms, which were established during a separate investigation of the same JSC \"Ukrbusbusprom\"--model 4289). In the case of frontal collisions of heavily loaded intercity buses at a speed of 32 km/h, this moment is reached even later--approximately 750-900 ms. This means much longer FEA calculations compared with the low-entry bus model studied here and significantly more computational resources. The number of finite elements in the intercity bus model is expected to be greater, also due to its more complex structure. The next configuration (two physical Intel Xeon 24-core processors, RAM of 48 GB, and NVIDIA GeForce 4 GB video) took 7 h and 48 min for the R29 (Explicit Dynamics) rules.