# Analysis of Conflict Distribution Characteristics between Motor Vehicles and E-Bikes at Roundabouts
## 4 Discussion and Conclusions  
Conflicts between vehicles and e-bikes at roundabouts are usually various. In this paper, the two most representative conflicts, Type 1 and Type 2, were discussed. Conflicts spatial distribution shows that Type 1 is mainly concentrated around the exit and the outermost circulatory lanes, while Type 2 is mainly concentrated at the interior of the outermost circulatory lanes and after the second stop line. Conflict distribution within one signal cycle show that conflicts increase rapidly before reaching a peak and then decrease gradually after that peak with the green time moving. Both types of conflicts reach a peak at 30 percentile green time, but the range of rapid increasing is different. Compared with conventional conflict types [40], many roundabouts in China are carried out with signal control and a second stop line, which will lead to the occurrence of Conflict Type 2, which is also different from other countries in terms of conflict types.  
Figure 14: Overall conflict distribution of Type 2.  
A safety assessments study of 50 urban roundabouts from Rome, Italy developed and validated a Safety Index (SI) for evaluating urban roundabouts and provided a Safety Index for a quantitative safety assessment of both roundabouts and roundabout approaches based on the presence of risk factors [41]. A report from Australia and New Zealand found that four-fifths of the conflicts at roundabouts were caused by drivers failing to give way to cyclists, suggesting that, in many cases, drivers did not realize the presence of the cyclists or misjudged their speed [30]. The conflict occurrence in this paper was mainly caused by the unclear road rights and unreasonable channelization, which is similar. Therefore, exclusive and colored e-bike lanes are necessary to further improve the e-bike's visibility and clarify its road rights. This will reduce the occurrence of conflict.  
This paper mainly analyzed the conflict distribution characteristics between vehicle and e-bike at roundabouts. Though the data of actual accidents was not obtained, the relationship between conflict and accidents was very related. By analyzing the two kinds of data, we can further excavate and avoid safety problems by setting up some traffic control devices at roundabouts. This could include designing advanced warning signs, perceptual measures, or delineation treatments in serious conflict areas to warn vehicles and e-bikes of the high risk of potential conflicts [42], which would be an interesting topic worthy of further study.  
The conclusions developed by this article could provide a theoretical basis for formulating improvement measures for roundabouts. Still there are several questions that need to be further explored. Because of the physical attributes, we only analyzed the defined roundabout types in our research. The conflicts between vehicles and e-bikes under different central island radii and control modes at roundabouts still need further study.  
Conceptualization, R.L. and G.L.; methodology, R.L. and G.L.; formal analysis, Y.C. and D.Z.; resources, B.W.; data curation, D.Z., writing--original draft preparation, R.L., G.L. and D.Z.; writing--review and editing, G.L. and R.L.; supervision, G.L. All authors have read and agreed to the published version of the manuscript. This research was supported by the General Program of the National Natural Science Foundation of China (No. 52172338), National Natural Science Foundation of China (No. 52002033).  
Not applicable.  
The data presented in this study are available on request from the first author.  
The authors declare no conflict of interest.