# Analysis of the Motion Sickness and the Lack of Comfort in Car Passengers
## 3 Methodology
### Journey, Driver and Car Selection  
The traversed route is shown in Figure 2b. The route covers a total of 26 km near Bilbao, in the north of Spain. It has been selected bearing in mind that it should contain representative and diverse sections, so as to asses the accelerations suffered by the passengers. It can be divided into 4 distinguishable sections:  
* Section 1 (S1): From point 1 to point 2 (3.7 km). An interurban road with altitude changes (it first goes up and then down), some smooth curves and a couple of 90 degree turns. The average speed is 61.36 km/h;
* Section 2 (S2): From point 2 to point 3 (5.2 km). An interurban section with a remarkable change in height that includes lots of curves. The average speed is 44.60 km/h;
* Section 3 (S3): From point 3 to point 4 (15.4 km). A flat highway with overtaking and lane change possibility. The average speed is 80.72 km/h;  
Figure 2: Selected data acquisition device and journey. **(a)** An example of a screenshot during data acquisition [53]; **(b)** selected 26-km journey near Bilbao, in the north of Spain.  
Section 4 (S4): From point 4 to point 4 (2.2 km). A circular urban section with zebra crossings, roundabouts, traffic lights and bumps. The average speed is 30.35 km/h.  
Figure 3 displays longitudinal, lateral and vertical accelerations experienced by the passengers across the representative journey. As it can be seen, there are meaningful differences among sections. For example, while section S3 (which corresponds to a highway) exhibits low accelerations in both longitudinal and lateral axes, S2 (a section with significant height differences) and S4 (an urban section) exhibit higher frequency accelerations, which are also higher in magnitude. Additionally, although the differences are smaller in the vertical axis, there are certain situations that show great values in magnitude. It has been verified that those situations correspond to zones where there are bumps.  
The aforementioned route has been covered by three different drivers and two different vehicles, so it has been completed six times. The objective of incorporating variability into the study is to analyze the effect on passenger comfort of both driving style, which could vary depending on the gender and age of the drivers, and vehicle dynamics, which can be influenced by the type and age of the cars. Drivers are identified as D1 (40/50-year-old man), D2 (20/30-year-old woman) and D3 (20/30-year-old man), whereas vehicles are designated as C1 (crossover type, Nissan Quashqay) and C2 (sedan type, Opel Vectra).  
The differences in the driving style are shown in Figure 4, a representative graph where longitudinal, lateral and vertical accelerations for the same car being driven by two drivers completing Section 2 are depicted. In fact, one driver (blue) covers the journey faster (300 s) and generates more brusque maneuvers (especially in lateral axis) than the other one (red), who has a more conservative driving style and needs 100 s more to complete the section. Concerning vehicle differences, Figure 5 displays the data collected during the journey driven by the same driver and using both cars. Differences can be observed in both lateral and longitudinal directions, while the vertical accelerations remain similar.  
It is expected that the disparity in road characteristics, driving style and vehicle dynamics will impact differently on passenger comfort. In the following sections, a comprehensive analysis of the causes associated with the lack of passenger's comfort will be conducted.  
Figure 3: Longitudinal, lateral and vertical acceleration experienced by the passenger across the representative journey.