# Drive on a Greener Way: A Case Study on Navigating Cross-Regional Traffic Networks in South China
## 6 Conclusions  
In this paper, we calculated the optimal route in the navigation process from a green perspective, addressing the problems of the lack of a sustainable mobility evaluation model and dynamic route planning algorithm for determining the greenest route. We analyzed three cases from South China with different service times, various types of roads, and variable weather conditions. Based on these cases, we demonstrated the effectiveness of the model and algorithm and compared the carbon emissions produced from vehicles and road maintenance. The conclusions are as follows:  
1. A sustainable mobility evaluation model that applies the LCA to measure carbon emissions is proposed. This model can calculate carbon emissions during periods of traffic from both vehicles and roads by considering vehicle fuel consumption, vehicle maintenance, periodic road maintenance, periodic road inspections, and additional road maintenance.
2. An algorithm for greenest route planning that combines static planning with dynamic adjustments is proposed. The A* algorithm calculates the static optimal route, where the road weight is the product of carbon emissions from vehicles and the proportion of carbon emissions from each road at an intersection. Considering the dynamic attributes of traffic conditions such as time, weather, and congestion levels, the near-real-time traffic state dynamic adjustment triggers and adjustment methods are proposed.
3. Three real-world traffic cases are proposed for South China. The results of the case study verify the effectiveness of the model and algorithm and compare the relationship with the shortest route. The carbon emissions caused by vehicles are much greater than the carbon emissions from road emissions. For these cases, decreasing the carbon emissions from vehicles is a more useful method than optimizing the road maintenance. When the road length is determined, shorter roads help to decrease the carbon emissions.  
The results of this paper are generalizable. The carbon emission evaluation model can be used in many different regions, unless there are other characteristics with great influences on the carbon emissions, such as steep roads. The navigation algorithm can be used in other traffic networks. The results of the comparison of vehicle carbon emissions and road carbon emissions are also generalizable unless some characteristics associated with road construction are present. For example, if the traffic network is in the desert, the carbon emissions associated with road maintenance will be increased and there may be an additional carbon emission associated with logistics.  
Upcoming work will address the issue of traffic flow as a whole. This will not only consider traffic factors but will also concentrate on the characteristics of regions, such as economic and social implications. It will also consider other carbon-containing materials used during road maintenance to construct more accurate and detailed methods for estimating the carbon emissions. In addition, equity and fairness in green route planning can be considered to add to the evaluation model and algorithm to make the results more objective and effective for other scenarios.  
Conceptualization, B.W. and J.S.; Methodology, Y.Z. ([PERSON]), Y.Z. ([PERSON]) and J.S.; Software, Y.Z. ([PERSON]) and Y.Z. ([PERSON]); Validation, J.S. and Y.Z. ([PERSON]); Formal analysis, Y.Z. ([PERSON]); Data curation, Y.Z. ([PERSON]); Writing--original draft, Y.Z. ([PERSON]); Writing--review & editing, J.S.; Visualization, Y.Z. ([PERSON]); Supervision, B.W. and J.S. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest.