Usually during the construction phase a quality control plan is applied which aims to ensure the appropriate installation and construction of all of the infrastructure project's elements. These plans should also include environmental follow up activities which aim to ensure that the construction activities are having minimum impact on the habitat and also that the measures are installed in the correct place, with the correct materials and dimensions and finalised according to the technical prescriptions established by the environmental impact studies.

This chapter does not aim to describe in detail this type of monitoring activity. However, a short check list is provided to draw attention to the main activities that can be included in the quality control plans to avoid the most common causes of failure of measures.

Aspects to be checked during the environmental follow up and quality control activities during the construction phase:

• Calendar of works. All works should be planned in such a way that disturbances are avoided to ponds and rivers during the amphibian breeding period and during the fish spawning season and also in the vicinity of birds' nests during breeding periods (especially birds of prey). Disturbances which affect amphibians and fish breeding sites include pollution or alteration of physical or chemical properties of the water and movement of soil. Disturbances affecting birds of prey include the movement of machinery and people and noise, especially the noise caused by blasting.
• Location of measures. Measures should be correctly located according to the guidelines established in the EIA.
• Fences. The dimensions and type of mesh should be checked. After installation it should be checked that the fence is well fixed to the soil with no opportunities for animals to pass underneath it.
• Fauna passages. It should be checked that the materials and dimensions are applied following the guidelines provided by the EIA. Other crucial points to check are that the surface is well formed with the correct planting and installation of other structures (stumps, stones, etc.). Access to the passage is also fundamental, including slope of ramps (when they exist), continuity of vegetation from the surrounding natural habitats to the passage and drainage of the surrounding areas. Often the drainage of cuttings or embankments near passages leads to flooding during periods of rain.
• Restoration activities. Disturbed areas which need to be restored or areas where compensatory measures are applied must be exhaustively monitored during the construction phase. It is important that species and ecotypes of plants have been correctly chosen and that irrigation and all the other systems that require maintenance have been installed. Restoration activities can also include the translocation of animals which requires specific control activities, such as the control of the origin population and sanitary aspects.
• Avoiding disturbances and pollution of adjacent habitats. The whole number of activities carried out during the construction of a road or railway can cause pollution to the adjacent soil or waters, and other disturbances originated by the movements of machines and workers. There are a large number of mitigation measures that can be carried out to ensure that all these impacts are minimised. 

A definition of follow up activities during the construction phase can be undertaken within the framework of standard norms, such as ISO 14001 (to minimise the environmental impacts) and ISO 9000 (to ensure the quality of works).