Urban transportation networks, from pavements and bicycle paths to streets and railways, provide the backbone for movement and socioeconomic life in cities. To make urban transport sustainable, cities are increasingly investing to develop their bicycle networks. However, it is yet unclear how to extend them comprehensively and effectively given a limited budget. Here we investigate the structure of bicycle networks in cities around the world, and find that they consist of hundreds of disconnected patches, even in cycling-friendly cities like Copenhagen. To connect these patches, we develop and apply data-driven, algorithmic network growth strategies, showing that small but focused investments allow to significantly increase the connectedness and directness of urban bicycle networks. We introduce two greedy algorithms to add the most critical missing links in the bicycle network focusing on connectedness, and show that they outmatch both a random approach and a baseline minimum investment strategy. Our computational approach outlines novel pathways from car-centric towards sustainable cities by taking advantage of urban data available on a city-wide scale. It is a first step towards a quantitative consolidation of bicycle infrastructure development that can become valuable for urban planners and stakeholders.

从人行道，自行车道到街道和铁路的城市交通网络，为城市的交通和社会经济生活提供了支柱。为了使城市交通可持续发展，城市越来越多地投资发展自行车网络。但是，在预算有限的情况下，如何全面，有效地扩展它们尚不明确。在这里，我们研究了世界各地城市的自行车网络的结构，发现它们由数百个不相连的路段组成，即使在像哥本哈根这样对自行车友好的城市中也是如此。为了连接这些补丁，我们开发并应用了数据驱动的算法网络增长策略，表明少量但有针对性的投资可以显着提高城市自行车网络的连通性和直接性。我们引入了两种贪婪算法，以在自行车网络中添加最关键的缺失链接（关注连接性），并表明它们在随机方法和基线最小投资策略上均不及预期。我们的计算方法通过利用整个城市范围内可用的城市数据，概述了从以汽车为中心到可持续城市的新颖途径。这是迈向定量整合自行车基础设施发展的第一步，这对于城市规划者和利益相关者而言可能变得很有价值。