In the initial planning stages of transport projects, archaeological investigation concentrates on the identification of known sites and areas of archaeological potential in order to inform the selection of the appropriate route.
Environmental Impact Statement
Following route selection and in tandem with the engineering and architectural design process further desk-based studies and field-walking of the preferred route are carried out as preparatory works for compiling the archaeological component of the Environmental Impact Statement (EIS). During this process it may also be possible to carry out archaeological investigations using techniques such as geophysical survey, underwater survey and test excavation. The results from these investigations inform the EIS of the archaeological potential of the route and of the measures that need to be put in place in order to improve the effects on archaeology.
Archaeological work during construction phase
Following approval of a scheme and during the construction phase all measures required to improve the effects on archaeology that were set out in the EIS are implemented. This may involve carrying out condition surveys and recording of upstanding archaeological sites and undertaking further archaeological assessments (e.g. geophysical surveys, test excavations) where these were not possible previously. Following completion of fieldwork a report is produced detailing the results of the assessment.
It is rarely possible to carry out testing before the main construction phase in developed urban areas due to the level of disturbance this would cause to traffic and to the public. As a result, archaeological monitoring of ground disturbance works is generally carried out in order to identify and protect archaeology.
Excavation and recording
Any sites identified through investigations and or monitoring which cannot be preserved will be archaeologically excavated and recorded before further construction works take place. Archaeological excavation involves the removal of topsoil or overburden layers, which cover the archaeological remains. Then each archaeological layer is removed and unpeeled in the reverse sequence in which it was deposited. Every stage is recorded on site through written descriptions, photography, sampling and drawings linked to a site survey grid.
Post-excavation documentation and reporting
Following completion of site works the study and analysis of all the records and finds that were retrieved from a site commences.This phase is called post-excavation and is an essential part of the process as it ensures that the site is fully recorded and documented for future generations. A report detailing the preliminary results of the excavation is produced initially.Following this the results of the detailed study and analysis, along with photographs and drawings are compiled into a final illustrated report of the site.