A Dispatch Strategy for Shared Bicycles Based on a Levels-of-Detail Model
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摘要: 公共自行车系统作为城市公共交通的重要组成部分,对于缓解城市交通拥堵和建设低碳、环保的出行体系起到了积极的作用。然而,由于公共自行车系统的借还车需求在时间和空间分布上存在不均衡性,在使用公共自行车时,经常遇到“借车难”或者“还车难”的问题,使得出行者不得不放弃使用公共自行车出行。为了有效地提升出行者借还公共自行车的成功率,研究了1种基于细节层次模型的自行车调度方法。基于公共自行车站点之间的相似度,采用谱聚类算法对站点进行层次划分,形成基于空间范围(即公共自行车站点所占据的地理空间区域)的站点簇;在每个划分层级上统计不同簇之间的自行车借/还需求,结合遗传算法对调度车辆的运输路径进行求解;将不同层级上的调度方案叠加,形成1种调度粒度由粗到细的自行车调度方案。通过对比实验证明:基于细节层次模型的公共自行车调度方法较传统方法减少了42.70%的调度路径,进而减少了相应的调度时间。Abstract: As an important part of urban public transportation, the shared bicycles have played a positive role in relieving traffic congestion and promoting a low-carbon, environmentally friendly travel system. However, people often encounter difficulties with borrowing or returning a bicycle when tending to use shared bicycles, due to the uneven temporal and spatial distributions of the demands of borrowing and returning bicycles. Such difficulties sometimes make travelers give up using shared bicycles. In order to effectively improve the success rate of borrowing and returning bicycles, a dispatch strategy based on a levels-of-detail model is proposed. First, based on the similarity among bicycles stations, a spectral clustering algorithm is adopted to hierarchically classify the areas where stations locate. Thus, station clusters are formed based on station scopes (i.e., the geographic spatial area of a public station occupied). Second, the total demand of borrowing/returning bicycles among different station clusters at each level is counted, and a genetic algorithm is adopted to solve the transport route for dispatch vehicles. Third, the dispatch strategies at each level are overlaid to form a dispatch strategy for shared bicycles with the granularity from coarse to fine. Compared with the traditional methods, the proposed strategy reduces the total length of dispatch path by 42.70%, and therefore the corresponding dispatch time can also be shortened accordingly.
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Key words:
- traffic engineering /
- dispatch strategy /
- shared bicycles /
- levels of details
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表 1 早高峰时各调度单元的自行车需求与相应的时间窗
Table 1. Demand and the corresponding time window of each rebalancing unit during morning peak
区域编号 锁桩数 需求量/辆 时间窗 C1 1 406 -141 08:20—09:20 C3 1 711 171 07:48—08:48 C11 341 -34 08:16—09:16 C12 490 -50 08:14—09:14 C22 507 -51 08:23—09:23 C31 672 68 07:51—08:51 C32 635 64 07:43—08:43 C111 90 -10 07:51—08:51 C112 136 -14 07:45—08:45 C113 115 12 07:38—08:38 C122 160 17 07:48—08:48 C123 155 -16 07:46—08:46 C132 170 18 08:05—09:05 C133 205 -21 08:08—09:08 C211 210 -22 08:14—09:14 C212 265 27 07:49—08:49 C213 250 -26 07:56—08:56 C221 180 19 07:41—08:41 C222 207 21 07:52—08:52 C223 120 -13 07:51—08:51 C231 155 16 08:21—09:21 C233 60 7 08:30—09:30 C311 225 23 08:09—09:09 C312 268 27 07:40—08:40 C313 179 18 08:18—09:18 C321 125 13 07:47—08:47 C322 195 20 07:37—08:37 C323 315 32 07:46—08:46 C331 130 -14 07:55—08:55 C332 150 16 07:38—08:38 C333 124 0 07:51—08:51 表 2 不同层级上各调度单元之间的调度方案
Table 2. Rebalancing scheme between each unit on different levels
调度区域 调度路径 调度的自行车数/辆 累计行驶距离/m 原始站点区域 C0→C1→C3→C0 312 5 799.84 1 C1→C12→C11→C1 84 3 886.81 11 C11→C113→C112→C111→C11 36 2 858.69 12 C12→C123→C122→C12 33 1 739.27 13 C13→C132→C133→C13 39 1 944.85 2 C2→C22→C2 51 1 617.62 21 C21→C212→C213→C211→C21 75 2 729.55 22 C22→C221→C222→C223→C22 53 2 782 23 C23→C231→C233→C23 23 5 055.13 3 C3→C32→C31→C3 132 2 543.63 31 C31→C312→C311→C313→C31 68 1 986.14 32 C32→C322→C323→C321→C32 65 4 133.90 33 C33→C332→C331→C33 30 3 033.95 表 3 传统调度方法的调度路径长度与调度时间
Table 3. The length of the path and the rebalancing time of the traditional method
调度线路 调度的行驶距离/m 耗费的时间/min 1 6 654.40 27.73 2 3 446.78 14.36 3 12 221.27 50.92 4 7 893.78 32.89 5 3 460.06 14.42 6 5 786.12 24.11 7 3 851.25 16.05 8 1 429.91 5.96 9 1 541.74 6.42 10 4 962.13 20.68 11 2 501.04 10.42 12 8 495.44 35.40 13 7 761.66 32.34 总计 70 005.58 291.70 表 4 基于层次调度方法的路径长度与调度时间
Table 4. The length of the path and the rebalancing time of the hierarchical method
调度区域 调度的行驶距离/m 耗费的时间/min 最上层调度区域 5 799.84 24.17 1 3 886.81 16.20 11 2 858.69 11.91 12 1 739.27 7.25 13 1 944.85 8.10 2 1 617.62 6.74 21 2 729.55 11.37 22 2 782 11.59 23 5 055.13 21.06 3 2 543.63 10.60 31 1 986.14 8.28 32 4 133.90 17.22 33 3 033.95 12.64 总计 40 111.38 167.13 -
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