# Impact of Environmental Factors on Passenger Ride Comfort
## 7 Results of Experimental Studies
### Thermal Comfort Results  
Figure 15 shows the average values of air temperature and relative humidity measured during the summer period in the passenger car and old-type metro trains. The results are presented against the proposed scale of thermal comfort (Figure 5). Measurements in the passenger car were carried out with the air conditioning switched off.  
\begin{table}
\begin{tabular}{c c c c c} \hline  & **Car, Main Road** & **Car, Local Road** & **Metro, New Train** & **Metro, Old Train** \\ \hline LAeq [dB(A)] & 73.5 & 81.6 & 77.9 & 82.6 \\ Comfort level C2 & 4 & 2 & 3 & 2 \\ \hline \end{tabular}
\end{table}
Table 10: Noise level LAeq and index of acoustic comfort C2 in passenger car and metro trains.  
Figure 14: Equivalent sound level adjusted by the A-weighting curve in metro trains and passenger car.  
The results of the temperature measurements in the metro show that the temperatures were similar in the two trains tested, which could indicate the same thermal conditions inside the vehicles. However, taking into account the average values for humidity, it must be concluded that better thermal comfort conditions were provided in the new metro trains. In the case of the passenger car, a significantly higher average temperature value was recorded during the journey, while at the same time, the air humidity was quite low. The results, together with the thermal comfort rating, are shown in Table 11.  
In summary, the new metro train offers the best thermal comfort of the three vehicles, while the passenger car and the old metro car reach a level of \"quite uncomfortable\" on the comfort scale. These results suggest a need to improve conditions, especially in the tested passenger car.  
The thermal conditions in the metro trains show clear differences compared to those observed in the Montreal metro [30]. In the present study, the average temperature of the old metro train was 26.7 \({}^{\circ}\)C with a relative humidity of 37.6%, resulting in a thermal comfort rating of 3 on the scale of C3. This indicates a \"quite uncomfortable\" level of thermal comfort, though still acceptable. In contrast, Montreal's old metro cars had significantly lower thermal comfort, scoring only 0.46 on the [0, 1] scale adopted in [30], which categorises this level of comfort as \"uncomfortable\".  
The new metro train in the Warsaw metro offers slightly better thermal conditions with an average temperature of 26.9 \({}^{\circ}\)C and relative humidity at 40.5%, corresponding to a comfort level of 4, close to the high end of the comfort scale from 1 to 5. Montreal's newer metro cars also achieve a higher rating, 0.64, than older cars, but still fall into the \"fair\" category as defined in [30].  
Importantly, the present study highlights that very low levels of relative humidity, such as those found in Montreal's metro system (less than 22%), can negatively impact passenger comfort. As in the present study, the scale of thermal comfort in the Montreal study is assessed based on a combination of temperature and relative humidity. However,  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Vehicle** & **Temperature [\({}^{\circ}\)C]** & **Relative Humidity [\%]** & **Confort Level C3** \\ \hline Car & 28.0 & 36.7 & 3 \\ Metro, new train & 26.9 & 40.5 & 4 \\ Metro, old train & 26.7 & 37.6 & 3 \\ \hline \hline \end{tabular}
\end{table}
Table 11: Temperature, relative humidity, and index of thermal comfort C3 in passenger car and metro trains.  
Figure 15: The average values of temperature and relative humidity in the passenger car and metro trains placed on the scale of thermal comfort (Figure 5).  
the temperature thresholds in that scale are constructed in such a way that comfort is considered the same, regardless of whether the relative humidity is 50% or as low as 10% for the same temperature of air. In contrast, the present study accounts for the effect of humidity on thermal comfort by emphasising the importance of maintaining sufficient humidity levels alongside temperature to ensure passenger well-being.