Most scholars conceive policy integration (PI) as a top-down process steered by governmental bodies and consider the formulation stage to be the decisive step for achieving PI. Adopting a different stance, this article hypothesizes that PI can also occur throughout the implementation stage thanks to “integration entrepreneurs” who are able and willing to bring together policies that were designed in silos. I test this hypothesis by analyzing the evolution of federal legislation intended to curb urban sprawl in Switzerland over four decades (1980–2020) and investigate three major urban renewal projects that concretely reduced urban sprawl in the cities of Zurich, Bern and Geneva. In line with my hypothesis, these urban renewal projects succeeded thanks to an ex post integration of several policies that occurred during the implementation stage. This integrative process was an unintended outcome of the transformation of the Swiss Federal Railways (SBB) from a federal government institution into a state-owned company. Since then, the SBB has become an “integration entrepreneur” who brings together three federal policies that were previously poorly integrated: the spatial planning policy, the railway policy and the agglomeration policy. Case study evidence thus shows that PI can also happen unintentionally, namely through coordination mechanisms that were not foreseen by policymakers at the formulation stage. This finding challenges the top-down sequential approach of the policy process that is dominant among PI studies and calls for more research on the role and the strategies of “integration entrepreneurs” throughout the implementation stage.

大多数学者将政策整合（PI）视为由政府机构主导的自上而下的过程，并认为制定阶段是实现PI的决定性步骤。本文采取不同的立场，假设 PI 也可以在整个实施阶段发生，这要归功于“整合企业家”，他们能够并且愿意将各自独立设计的政策整合在一起。我通过分析四十年来（1980-2020）旨在遏制瑞士城市扩张的联邦立法的演变来检验这一假设，并调查了三个具体减少苏黎世、伯尔尼和日内瓦城市扩张的主要城市更新项目。根据我的假设，这些城市更新项目的成功得益于实施阶段的多项政策的事后整合。这一整合过程是瑞士联邦铁路 (SBB) 从联邦政府机构转变为国有公司的意外结果。自此，SBB成为一名“整合企业家”，将之前整合不佳的三项联邦政策整合在一起：空间规划政策、铁路政策和集聚政策。因此，案例研究证据表明，PI 也可能在无意中发生，即通过政策制定者在制定阶段未预见到的协调机制发生。这一发现挑战了在 PI 研究中占主导地位的政策过程中自上而下的顺序方法，并要求对“一体化企业家”在整个实施阶段的角色和策略进行更多研究。