# Research on Vibration Comfort of Non-Motorized Lane Riding Based on Three-Axis Acceleration
## 4 Experimental Results Analysis
### Ranking of Importance of Random Forest Variables  
(1) Order of importance  
The variables were ranked based on their significance, in descending order: with or without non-motorized lanes, with or without human non-isolation, riding speed, the number of roadway articulated protrusions, with or without on-street parking area, type of non-motorized vehicle, number of manhole covers, with or without machine non-isolated, number of intersections, percentage of e-bikes, number of bus stops, number of access points, and number of turns (see Figure 2 for details).  
\begin{table}
\begin{tabular}{l l l} \hline \hline
**Variable Name** & **Value Type Variable Type** & **Variable Type** \\ \hline Comfort level & 1 = slightly uncomfortable, 2 = very & Dependent variable \\  & uncomfortable & \\ Number of bus stops & 1 = 0–5, 2 = 6–10, 3 = \textgreater{}10 & Independent variable \\ Number of intersections & 1 = 0, 2 = 1, 3 = \textgreater{}1 & Independent variable \\ Number of access points & 1 = 0–5, 2 = 6–10, 3 = \textgreater{}10 & Independent variable \\ Number of turns & 1 = 0, 2 = 1–3, 3 = \textgreater{}4 & Independent variable \\ With or without non-motorized lanes & 1 = no, 2 = yes & Independent variable \\ With or without machine non-isolated & 1 = no, 2 = yes & Independent variable \\ With or without human non-isolation & 1 = no, 2 = yes & Independent variable \\ With or without on-street parking area & 1 = yes, 2 = no & Independent variable \\ Number of manhole covers & 1 = 0, 2 = 1–4, 3 = \textgreater{}4 & Independent variable \\ Number of roadway articulation protrusions & 1 = 0, 2 = 1–5, 3 = 6–10 & Independent variable \\ Type of non-motorized vehicle & 1 = bicycle, 2 = electric bicycle & Independent variable \\ Percentage of e-bikes & 1 = low, 2 = medium, 3 = high & Independent variable \\ rRding speed & 1 = low, 2 = medium, 3 = high & Independent variable \\ \hline \hline \end{tabular}
\end{table}
Table 2: Variable assignments.  
Figure 2: Order of importance of variables.  
Employing a stepwise random forest approach, beginning with the highest-ranked variable based on the importance score, this study observed that the out-of-bag estimation error rate remained low and stable when limited to six variables. The top six variables, according to their importance scores, were absence of non-motorized lanes, lack of non-motorized segregation, cycling speed, the number of articulated protrusions on the roadway, the division of non-motorized lanes into parking zones, and the type of non-motorized vehicles (refer to Figure 3 for more details). Consequently, this paper infers that with or without non-motorized lanes, with or without human non-isolation, riding speed, the number of roadway articulation protrusions, with or without on-street parking area, and the type of non-motorized vehicles significantly impact riding vibration comfort. In contrast, the influence of the number of manhole covers, with or without machine non-isolated, the number of intersections, the percentage of e-bikes, the number of bus stops, the number of intersections, and the number of turns on riding vibration comfort is not substantial. Among the first six significant influences, in terms of road characteristics, road cross section and road surface are mostly significant factors, while road alignment and longitudinal section are in a non-significant position; in terms of traffic flow characteristics, speed and non-motorized vehicle models are a significant influence, while other influences are significant. In conclusion, it can be seen that the factors of road cross section and road surface as well as the speed of traffic flow and non-motorized vehicle models have a significant effect on riding vibration, while the route alignment and the percentage of different traffic flows have little effect on riding vibration.