Chartered Institute for Archaeologists 2023

22 Geophysical survey results, Iron Age and Roman settlement ©HS2 Approaches to evaluation and assessment for linear infrastructure: HS2 Phase One John Halsted MCIfA, HS2 LTD In this case study, John Halsted outlines the approach to the assessment and evaluation of archaeological potential and impact on a mega-project, the construction of the High Speed 2 (HS2) rail link. HS2 may not be a ‘typical’ project but it has provided opportunities to test evaluation techniques on a large scale. The HS2 Historic Environment Research and Delivery Strategy (HERDS) emphasises the importance of using competent, accredited professionals to design and deliver appropriate programmes of work which minimise risk and maximise the opportunity for archaeological work to create value for business and society. HS2 Phase One extends for 225km across the landscape through a variety of topographical and geological areas and potentially a wide variety of archaeological remains. Through the Environmental Minimum Requirements, notably the Heritage Memorandum, 1 a programme of historic environment works was enacted in advance of construction. HS2 as a client, employed a number of contractors in a tiered supply chain in order to deliver and manage the archaeological works alongside an in-house embedded historic environment team. A strategy was developed, following a process of industry and stakeholder consultation, which sought to focus upon clear objectives for archaeological investigation (the Historic Environment Research and Delivery Strategy) 2 . In order to better understand and define the location of archaeological assets, a variety of different methods were applied which can provide a useful insight into the potential approaches to evaluation. In support of the Hybrid Bill process and in advance of the Heritage Memorandum, the scheme was subject to an Environmental Impact Assessment. 3 This sought to establish the known heritage assets on the scheme and the potential impacts of the scheme design on those assets. 4 This assessment also included defining a series of archaeological character areas as a means of providing an overview of archaeological potential across different landscapes. Building on this work, with the initial ‘urgent works’ construction programme in mind, an archaeological risk model was developed. From a construction perspective, areas of higher risk were determined on the basis of locations where relatively little was known but where a set of criteria 1 Environmental minimum requirements for HS2 Phase One – GOV.UK (www.gov.uk ) 2 https://www.gov.uk/government/publications/hs2-phase-one-historic-environment-research-and-delivery-strategy 3 HS2 Phase One environmental statement: documents – GOV.UK (www.gov.uk ) 4 HS2 Phase One environmental statement volume 5: cultural heritage – GOV.UK (www.gov.uk )