Poor mobility limits the productivity benefits of cities

Cities make firms more productive by bringing workers, customers, suppliers, and ideas closer together.

城市通过将工人、客户、供应商和创意更紧密地联系在一起，提高企业的生产力。

Yet in many rapidly growing cities in developing countries, severe congestion makes physical proximity deceptive: firms may be located close to one another yet remain difficult to reach.

然而，在发展中国家的许多快速发展的城市中，严重的拥堵使得物理上的接近具有欺骗性：公司可能彼此靠近，但仍然难以到达。

A recent paper shows that this distinction matters.

最近的一篇论文表明这种区别很重要。

Density generates productivity benefits, but they vary considerably across cities and are substantially smaller where mobility is poor, particularly where congestion is severe.

密度会产生生产力效益，但不同城市的生产力效益差异很大，在流动性较差的地方，特别是在交通拥堵严重的地方，效益要小得多。

A city can therefore be physically dense but economically disconnected.

因此，一个城市可能物理上密集，但经济上却孤立无援。

To reduce the erosion of economic benefits in dense cities, governments can implement anti-congestion policies as they work toward improving urban connectivity infrastructure.

为了减少密集城市经济效益的侵蚀，政府可以在努力改善城市连通基础设施的同时实施反拥堵政策。

The evidence on whether firms in developing countries’ metropolitan areas benefit from agglomeration economies—the productivity gains through sharing, matching, and learning in a city—is mixed.

关于发展中国家大都市地区的企业是否受益于集聚经济（通过在城市中共享、匹配和学习而提高生产力）的证据好坏参半。

Some studies find strong urban density effects similar to those observed in developed countries, consistent with the idea that clustering allows businesses to share resources and learn from one another, match with workers and suppliers more efficiently, and improve market access.

一些研究发现，城市密度效应与发达国家相似，这与集群允许企业共享资源、相互学习、更有效地匹配工人和供应商以及改善市场准入的理念相一致。

Others find evidence of “sterile” agglomerations due to diseconomies such as traffic congestion, crime, exposure to pollution and disease, and greater competition for centrally located real estate.

其他人则发现了由于交通拥堵、犯罪、污染和疾病以及对市中心房地产的激烈竞争等不经济因素导致的“无菌”聚集的证据。

The literature suggests that these differences partly reflect different choices for outcomes (nominal wages versus productivity measures) and differences across industries (manufacturing versus services) and types of labor (skilled versus unskilled).

文献表明，这些差异部分反映了结果选择的不同（名义工资与生产率指标）以及行业（制造业与服务业）和劳动力类型（熟练与非熟练）之间的差异。

A recent paper examines another possible source of this variation: differences in urban mobility, differentiating between slow traffic throughout the day and very slow traffic during peak business hours due to congestion.

最近的一篇论文研究了这种变化的另一个可能来源：城市交通的差异，区分全天交通缓慢和高峰时段由于拥堵而导致交通非常缓慢。

When movement within a city is slow, the effective distance between workers, firms, and consumers increases, reducing opportunities for sharing, matching, learning, and market access.

当城市内的流动缓慢时，工人、企业和消费者之间的有效距离就会增加，从而减少共享、匹配、学习和市场准入的机会。

In developing countries, such mobility issues may also entrench informality in unequal cities .

在发展中国家，这种流动性问题也可能会加剧不平等城市的非正规性。

Slow traffic throughout the day due to poor road networks makes it difficult to reach distant low-income neighborhoods, while very slow traffic due to congestion makes even nearby poor neighborhoods difficult to access.

由于道路网络较差，全天交通缓慢，难以到达遥远的低收入社区，而由于拥堵，交通非常缓慢，甚至导致附近的贫困社区也难以到达。

To investigate how mobility problems reduce firms’ returns to density in the developing world, the paper combines geocoded firm-level data from the World Bank Enterprise Surveys with a unique global database of urban mobility indices built from more than 530 million simulated trips on Google Maps.

为了研究流动性问题如何降低发展中国家企业的密度回报，本文将世界银行企业调查中的地理编码企业级数据与根据谷歌地图上超过 5.3 亿次模拟出行建立的独特的全球城市流动性指数数据库结合起来。

The final sample includes 38,526 firms located in 356 metropolitan areas across 80 developing countries.

最终样本包括位于 80 个发展中国家 356 个大都市区的 38,526 家公司。

The mobility data distinguish between two related but different challenges: low uncongested travel speeds (slow movement even when traffic is light) because of poor road quality or underdeveloped road networks) and much lower speeds due to congestion delays, captured as the additional travel time caused by peak-hour traffic.

出行数据区分了两个相关但不同的挑战：不拥堵的行驶速度较低（由于道路质量差或道路网络不发达，即使交通畅通，行驶速度也很慢），以及由于拥堵延误而导致的速度低得多，这被视为高峰时段交通造成的额外行驶时间。

The distinction matters because these problems have different origins and may require different policy responses.

这种区别很重要，因为这些问题有不同的根源，可能需要不同的政策反应。

The paper finds that urban density generates productivity gains for firms, but these gains are substantially smaller when mobility is constrained.

该论文发现，城市密度可以为企业带来生产力提升，但当流动性受到限制时，这些收益会大幅减少。

The implication is that cities are unlikely to realize the full returns to densification unless urban growth is accompanied by improvements in connectivity and accessibility.

这意味着，除非城市增长伴随着连通性和可达性的改善，否则城市不太可能实现致密化的全面回报。

Extremely low speeds due to congestion emerge as the more powerful constraint compared with slow traffic throughout the day, because it more severely weakens firms’ ability to do business in dense urban environments.

与全天缓慢的交通相比，由于拥堵而导致的极低速度成为更强大的限制，因为它更严重地削弱了企业在密集的城市环境中开展业务的能力。

The estimates presented in the paper suggest that the erosion of agglomeration economies due to congestion is approximately 2.5 times larger than the erosion associated with slow traffic due to poor city roads.

论文中提出的估计表明，拥堵对集聚经济的侵蚀大约是城市道路状况不佳导致交通缓慢造成的侵蚀的 2.5 倍。

Firms operating in nontradable sectors—such as retail, restaurants, local services, transportation services, and personal services—are more vulnerable to congestion constraints than manufacturing firms because the production and consumption of these services take place at the same time and place.

从事非贸易部门（例如零售、餐饮、本地服务、运输服务和个人服务）的企业比制造企业更容易受到拥堵约束，因为这些服务的生产和消费是在同一时间和地点进行的。

Businesses offering nontradable services therefore depend heavily on face-to-face interactions and local markets for workers and customers.

因此，提供非贸易服务的企业在很大程度上依赖于面对面的互动以及工人和客户的当地市场。

When congestion increases travel times, their effective market size shrinks.

当交通拥堵增加出行时间时，其有效市场规模就会缩小。

Customers and workers are less willing to travel, and business interactions become more costly.

客户和员工出差的意愿降低，业务互动的成本变得更高。

Manufacturing and export-oriented firms appear less exposed to these constraints because they rely more on global transactions and less on local demand.

制造业和出口导向型企业似乎较少受到这些限制，因为它们更多地依赖全球交易，而不是本地需求。

Although manufacturing workers must travel to their factories, these facilities are often located on the outskirts of cities, in more remote but less congested neighborhoods.

尽管制造业工人必须前往工厂，但这些设施通常位于城市郊区，较偏远但不那么拥挤的社区。

Firms also have more ways to adapt, for example, by providing transportation services for their workers, adjusting their work or shipment schedules, and holding inventories.

企业还有更多的适应方式，例如为员工提供交通服务、调整工作或发货时间表以及持有库存。

As a result, their productivity gains from density are less severely reduced by traffic congestion.

因此，他们因密度而提高的生产率不会因交通拥堵而受到严重影响。

Similar patterns appear when comparing nonexporting firms with exporters and domestic firms with foreign-owned firms.

当比较非出口企业与出口企业以及国内企业与外资企业时，会出现类似的模式。

The latter are better capitalized than domestic firms and therefore have funds to adapt.

后者的资本比国内企业更好，因此有资金来适应。

They also have more affluent customers who can afford to travel longer distances or live in proximity to these companies, which are typically located in central business districts.

他们还拥有更富裕的客户，他们可以负担得起长途旅行或住在这些公司附近，而这些公司通常位于中央商务区。

The debate about urbanization in developing countries often focuses on whether cities are too crowded.

关于发展中国家城市化的争论往往集中在城市是否过于拥挤。

This study suggests a different perspective: the problem is not density itself, but the inability to move efficiently within dense cities.

这项研究提出了不同的观点：问题不在于密度本身，而在于无法在密集的城市内有效地移动。

The central policy challenge is therefore to make density work by coordinating urban development, connectivity, and accessibility.

因此，核心政策挑战是通过协调城市发展、连通性和可达性来提高密度。

Improving mobility and reducing congestion in fast-growing developing countries’ metropolitan areas is a complex task, which requires financing and well-implemented, multipronged strategies.

在快速发展的发展中国家的大都市区改善流动性并减少拥堵是一项复杂的任务，需要融资和实施良好的多管齐下的战略。

These often combine long-term plans for mass transit system development with policies that increase the relative attractiveness of public transportation (for example, through congestion pricing, parking charges, and fuel subsidy cuts), align land-use planning with transportation investments, and improve digital connectivity to reduce travel needs and ease pressure on transport networks.

这些措施通常将公共交通系统发展的长期计划与提高公共交通相对吸引力的政策（例如，通过拥堵费、停车费和燃油补贴削减）结合起来，使土地使用规划与交通投资相结合，并改善数字连接以减少出行需求并缓解交通网​​络的压力。

The new research does not identify which individual intervention is most effective, and the appropriate combination will depend on local conditions.

新研究并未确定哪种个体干预措施最有效，适当的组合将取决于当地情况。

However, it strengthens the case for congestion pricing because it shows that each driver imposes an externality not only on those behind them in traffic but also on firms and people across the city through diminished agglomeration economies.

然而，它强化了拥堵定价的理由，因为它表明，每个司机不仅对交通中落后的人施加外部性，而且通过减少集聚经济，对整个城市的企业和人民施加外部性。

The policy conclusion is that local governments should prioritize anti-congestion measures while implementing their long-term plans for developing well-functioning urban connectivity infrastructure.

政策结论是，地方政府应优先考虑反拥堵措施，同时实施发展运转良好的城市互联基础设施的长期计划。

This way, fast-growing cities will be able to realize the full productivity benefits of densification.

这样，快速发展的城市将能够充分实现致密化带来的生产力优势。

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