The incorporation of data from archaeological works into the BIM process will reduce capital cost over the project life cycle for large-infrastructure projects, but most people don’t realise how it will benefit them and contribute to this key objective of BIM adoption
Broadly speaking the work of the archaeological contractor during the CAPEX phase of an infrastructure project can be broken down into three parts; analysis and assessment of known heritage assets, evaluation of potential archaeological remains within the scheme, and, finally, mitigation and monitoring during construction. In this article we will consider the first of these processes, assessment and analysis, which is completed during the initial phases of a project whilst concern is still being given to the final design. A second article will follow that looks at the more fieldwork intensive evaluation and mitigation works. Both articles are written under the umbrella of a general premise; that the archaeological record produced through the work of the archaeological contractor doesn’t need to be shared through BIM.
By its very nature the assessment and recording of archaeology is a data heavy process; an assessment synthesises information from a large range of different sources, and in most cases all archaeological remains within the footprint of a scheme are destroyed, leading us to use a process called preservation by record. This means that the remains are recorded using a set of industry standard processes, such as the creation of written and drawn records, a photographic archive and survey data. In the recording of a single archaeological feature numerous pieces of data are captured as we record the nature and extent of the heritage asset that we are losing.
The incorporation of all of this data into a federated model would do little except contribute towards bloating it and making it clumsier to use: what is required is an understanding of the information that would assist other members of the planning and construction teams, and its delivery at the appropriate level of definition.
Another thing that needs outlining before we consider the exchange of data is the dynamic nature of the work to be undertaken in discharging archaeological planning conditions. The extent and significance of archaeology often remains unknown until the evaluation phase is undertaken, and even then significant features can still be identified during the monitoring of topsoil stripping by non-archaeological contactors. As such archaeological works can be programmed to run consecutively with other construction works at short notice, having to be accommodated into work programmes that have been planned for some considerable time.
In any project preparation is key and at the very outset of any construction project an assessment is carried out using known heritage assets within the scheme and its immediate environs, alongside any available documentary or cartographic evidence; this can inform the construction in several key aspects.
In performing an assessment a wealth of information is collated, drawing upon sources such as the National Monuments Records, the Historic Environment Record, historic mapping, local archives and previous archaeological reports to name a few.
This is often supplemented in larger schemes with initial pieces of fieldwork, such as walkover surveys, geophysical surveys and, increasingly, UAV based photogrammetric survey. We are now seeing the facility to perform LiDAR survey from UAVs being increasingly offered as a service and this, coupled with the release of the LiDAR data collected by the Environment Agency as Open Data, means that we have the potential to understand landscapes like never before.
The collation and assessment of this information allows for key assertions to be made that are used to inform the construction process in the following ways;
- It allows all stakeholders, including monitoring bodies, to understand the impact of the proposed construction on the historic environment;
- It evaluates the risk of encountering previously unknown archaeological remains and the impact of the proposed development on known heritage assets;
- It enables the design team to understand any heritage related limitations that may be encountered during construction, and informs the methodology for any subsequent archaeological work that may be required to discharge planning conditions placed on the proposed development.
By sharing through BIM data relating to these assertions made at the assessment stage, it allows other members of the supply chain to understand the risks and limitations that would be associated with a construction project and facilitate optimised planning and design to mitigate them.
Chris Breeden
Senior Geomatics Officer
Wessex Archaeology
Tel: 0114 255 9774
