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Abstract
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Background
Cycling has been an important mode of transportation that enhances transportation sustainability by reducing air and noise pollution as well as traffic congestion. This study seeks to improve the methodology for determining the relationship between cycling dynamic performance and roadway environment characteristics across different bicyclists' skill levels. We examined two facets of performances: mobility and comfortability.
Methods
To achieve the goal of this study, an Instrumented Probe Bicycle (IPB) equipped with various sensors was built. Using sensors allowed us to monitor bicyclist interactions to roadway environment and dynamic movements. A naturalistic field experiment, including intersections, roundabout, alignment changes, and different road surface conditions, was conducted. The Pavement Surface and Evaluation Rating System (PASER) was used to determine the quality of road surfaces. In addition, two self-reported questionnaires were used in order to obtain each participant's skill level as well as their perception on the level of cycling comfortability.
Results
Fault Tree Analysis was employed to develop the performance measures for recognizing the probability of fault event occurrence. Bicycle speed is being used to measure the mobility performance of the bicycle environment system. The probability that a particular segment fails to support a rider is defined as mobility performance failure. Moreover, the bicycle dynamic movements as well as the PASER rating estimate the comfortability level of the bicyclists. The probabilistic outcome of the proposed Ordered Probit Model was considered to develop the Cycling Comfortability Index (CCI). CCI is a continuous value between 0 and 1, which is adopted to find the probability of comfort level for each observation. At the end, by having two failure probabilities (mobility and comfort), the probability of a fault event occurrence is calculated.
Conclusions
We found that the probability of a fault event occurrence, was strongly related to the bicyclist's level of experience. The fact that inexperienced bicyclists had higher failure ratio implies that their levels of mobility and comfortability are lower. In addition, the quality of road surface had a significant impact on the speed as well as the comfortability index. The Ordered Probit Model showed that cycling comfortability was significantly affected by the average Y-axis acceleration and the mean absolute deviation of Z-axis velocity. Steering movements and Z-axis angular movements (yawing) also affected cycling comfortability. The IPB developed in this study turned out to be very useful in collecting cycling maneuver data and in analyzing bicycle safety associated with bicycle infrastructure. |