Urban transportation systems are vulnerable to congestion, accidents, weather, special events, and other costly delays. Whereas typical policy responses prioritize reduction of delays under normal conditions to improve the efficiency of urban road systems, analytic support for investments that improve resilience (defined as system recovery from additional disruptions) is still scarce. In this effort, we represent paved roads as a transportation network by mapping intersections to nodes and road segments between the intersections to links. We built road networks for 40 of the urban areas defined by the U.S. Census Bureau. We developed and calibrated a model to evaluate traffic delays using link loads. The loads may be regarded as traffic-based centrality measures, estimating the number of individuals using corresponding road segments. Efficiency was estimated as the average annual delay per peak-period auto commuter, and modeled results were found to be close to observed data, with the notable exception of New York City. Resilience was estimated as the change in efficiency resulting from roadway disruptions and was found to vary between cities, with increased delays due to a 5% random loss of road linkages ranging from 9.5% in Los Angeles to 56.0% in San Francisco. The results demonstrate that many urban road systems that operate inefficiently under normal conditions are nevertheless resilient to disruption, whereas some more efficient cities are more fragile. The implication is that resilience, not just efficiency, should be considered explicitly in roadway project selection and justify investment opportunities related to disaster and other disruptions.

中文翻译：

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运输网络的弹性和效率。

城市交通系统易受交通拥堵，事故，天气，特殊事件和其他代价高昂的延误的影响。尽管典型的政策应对措施优先考虑在正常情况下减少延误，以提高城市道路系统的效率，但仍缺乏对提高抵御能力（定义为从其他中断中恢复系统）的投资的分析支持。在这项工作中，我们通过将路口映射为节点并将路口之间的路段映射为链接，将铺装的道路表示为交通网络。我们为美国人口普查局定义的40个市区建立了道路网络。我们开发并校准了一个模型，以使用链路负载评估流量延迟。可以将负荷视为基于交通的集中度度量，以估计使用相应路段的人数。效率被估算为每个高峰期自动通勤者的年平均延误，发现建模结果与观察到的数据接近，纽约市除外。复原力被估计为道路中断导致的效率变化，并且发现在城市之间存在差异，由于5％的随机失去道路联系而造成的延误增加，从洛杉矶的9.5％到旧金山的56.0％不等。结果表明，许多在正常条件下运行效率低下的城市道路系统仍能抵御干扰，而一些效率更高的城市则更加脆弱。这意味着在道路项目选择中应明确考虑应变能力，而不仅仅是效率，并证明与灾难和其他破坏相关的投资机会是合理的。