Societies continuously modify infrastructure to meet changing societal needs. To do so, multiple organisations represent the interests of a myriad of stakeholders within the infrastructure planning process. With diverse, even competing, perspectives, it is challenging to build consensus for infrastructure modifications, ultimately leading to society not meeting its needs optimally. To better meet societal needs, it is necessary to step back and evaluate the planning process as a whole, and determine how the process can be improved. For societies to review their infrastructure planning processes, this paper introduces for the first time the concept of the responsiveness of the process, which specifically goes beyond the well-studied planning of specific projects. Responsiveness is demonstrated as a concept that captures how quickly a society is able to modify infrastructure to meet societal needs. The concept is illustrated using an example of a fictive but realistic process for planning highways in Zurich Oberland, Switzerland. The changes in the infrastructure planning process responsiveness are evaluated for impact on societal needs using eight process variations and multiple future scenarios. The societal needs are quantified over time using owner and user costs considering uncertain road user numbers and uncertain delivery date.