A set of process-related barriers negatively determines the effectiveness of EIA in transport planning. Recent research highlights in particular the unstructured stakeholder involvement and inefficient public participation during the scoping phase of EIA as key bottlenecks. While the academic literature has produced several promising theories for addressing these barriers, they have rarely been translated into solutions applicable and testable in practice.
In order to bridge this theory–practice gap, we present a systematic literature review of interventions and mechanisms aimed at facilitating the integration of different sources and types of knowledge during the scoping phase of EIA. This review explores if and how interventions and mechanisms have been conducted in practice; if and why they worked or did not work; and how relevant they are for EIA in transport planning. Based on this review, we distil a set of three specific interventions and trigger mechanisms applicable in the context of EIA in transport planning based on: i) balancing between too much and too little information and complexity; ii) using the EIA to facilitate a social learning process; and iii) adapting the participatory process to the specific characteristics of EIA in transport planning.