Addressing cumulative effects due to transport infrastructure should be a strategic planning exercise, and involves their consideration in master plans. Master plans offer the opportunity to handle these complex multiple interactions taking a systemic approach (see Chapter 4 – Integration of infrastructure into the landscape). Whilst master plans are expected to be on the right scale of analysis and management (see Chapter 2 – Policy, strategy and planning), some are inadequately designed, and this has an effect on their use for effective identification and management of cumulative impacts.
The impact assessment is the developer’s responsibility which limits its ability in coordinating with multiple actors from different types of activity and thus evaluating its own contribution to cumulative impacts. This statement is true at the project level (EIA), where the developer has limited coordination with other project developers. But this issue also applies to strategic planning, where the local authorities responsible for the SEA have a limited amount of information from multiple project developers.
Master plans often only include known projects by the local authorities and generally do not record other projects occurring in the same area nor make projections of planned future projects. The specifications of these other projects are therefore not considered for the conception of the master plan, as the project’s developers have their own timeline that does not match the schedule of the strategic planning. This results in cumulative impacts created by the interactions of several projects for which no mitigation has been planned. A more appropriate analyses would be to conduct thorough SEAs to consider all potential cumulative impacts in a same landscape or jurisdiction and use these assessments to guide project level EIA. A complete change in impact assessment governance at the spatial planning scale is therefore required where the planning administration of a given jurisdiction should lead the coordination, the management, and the monitoring of cumulative impacts on behalf of all project developers operating in its territory. All the expected impacts in terms of spatial consumption by any type of project are pooled, as illustrated in the section concerning the role of master plans in the avoidance and compensation steps (Figure 3.2.1 and Figure 3.4.1), but this approach is still new and should be developed more widely.