This phase applies to specific construction projects undertaken to modify infrastructure under operation with different purposes which can be combined, such as to improve safety, increase capacity and enhance resilience of the infrastructure. Joining two or more infrastructure together in the same transport corridor (‘bundling’) could also be a motivation.
To reduce impacts of existing transport infrastructure on nature and benefit biodiversity must also be a goal to be included in any infrastructure upgrade or adaptation project. It may also be the primary goal for infrastructure upgrade. Defragmentation plans are the tool allowing to analyse the impacts of the infrastructure and to design solutions to be applied to restore ecological connectivity, avoid wildlife mortality or reduce disturbance caused by existing infrastructure. In these specific situations, the general principles of planning, design, construction, and maintenance described in previous chapters should be followed.