During the planning process multiple planning parameters are dealt with at the same time and the proposed solution is often a result of several functional, economic and environmental factors. It can be very difficult to isolate the costs that are related to fragmentation issues. An integrated approach and an iterative planning process will help develop effective solutions with low costs and high benefits. Frequently the choice of solutions determined by the topography can significantly reduce the costs of mitigation measures. In other situations the use of waste material to construct overpasses can be a low cost solution.

A description of costs related to fragmentation should include:

• Costs derived from avoiding fragmentation by choosing longer or more expensive routes and alignments.
• Costs derived from mitigation measures and fences added to the project for defragmentation purposes.
• Costs derived from the limitation to optimise on other functional aspects of the infrastructure.
• Costs derived from compensation measures caused by the fragmentation of the road or rail scheme.

A description of benefits related to fragmentation issues should include:

• Benefits derived from the long-term conservation of nature and biodiversity in general.
• Benefits from maintaining ecological coherence in the landscape.
• Benefits derived from preserving habitats for vulnerable species. •
• Benefits from avoiding traffic accidents caused by wildlife.

The value of nature and biodiversity conservation can be described on the basis of a Willingness-to-Pay method. Interpretation of results from these methods should take into account that avoiding, mitigating or compensating for habitat fragmentation is a long-term benefit which is often irreversible. In other words, benefits will persist as long as the relationship between infrastructure and the ecological structure is under pressure. Often benefits could increase over time when new infrastructure has secondary effects on urbanisation or other landuse change which increase pressure on habitat fragmentation. The calculation of benefits should therefore take into account the long-term efficacy of avoidance and mitigation measures.

Existing older structures on roads and railways can often function as mitigation measures with only small changes or adaptations. These investments are not always critical to habitat fragmentation but can strengthen the ecological coherence of the surrouding landscape. In this situation, even small costs can have significant benefits. The recommended planning method is described in Section 5.5.