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Context of the AIR research project

On this page you can find out about:

  • the international context of the AIR research project within urban environments;

  • the origins of the AIR research project, within academic study, between 2007 and present;

  • the practical and academic relevance of the research, internationally;

  • the processes of developing the AIR processes and why they were undertaken, including how they were applied to the interfaces of metro infrastructure across the world;

  • see how the AIR research is applicable to other forms of transport infrastructure and its environment;

  • findings from the collective 2007-2019 research;

  • and see the aim of the AIR research prpoject.

Urbanisation and densification

As global populations increase (United Nations, undated), cities become denser. Within those cities are existing urban infrastructure. That infrastructure takes many and various physical forms. I.e., buildings, utilities networks, and transport systems, which also have many and varied ages and methods of construction. The infrastructure is also owned, maintained, and used, by many and varied urban stakeholders. Its safe continued presence and operation is therefore essential to enable urban environments to function.

For example, note how in Fig.1, a variety of types of urban infrastructure are represented, including buildings with multiple levels above and below ground, public open space, highway, and metro infrastructure. This infrastructure is owned/maintained by many and varied urban stakeholders and is subsequently managed according to their needs.

Fig.1: Central China’s mega-city Wuhan has started the construction of the country’s largest “underground city,” as more cities look to underground space as land resources become scarce. Source: Hubei, 2015.


Due to the interconnected and interdependent nature of urban infrastructure and its environment, densification of those urban environments causes what Bobylev, 2009, referred to as ‘rivalness and excludability’. I.e. the needs or use of land by one urban stakeholder, over-riding the needs or use of land by other urban stakeholders.

As such, the existing and proposed presence, property, and protection interfaces of urban infrastructure (where something is present, someone must own it, and its safe continued presence and operation must be protected), must be effectively managed during periods of urban change and urban management. Failure to do so can have potentially catastrophic effects to the use of urban space, its infrastructure, and its stakeholders.

For example, Fig.2, shows an example of the rivalness and excludability within the urban environment of London, where foundations for a new development were proposed to intercept an existing tube railway tunnel (discussed further on the Example  UUMI interfaces page).

Fig.2: Showing an example of urban ‘rivalness and excludability’, where foundations for a new development were unintentionally designed to conflict with a tube-railway tunnel, in London, UK. Source: RAIB, 2014.


Ongoing research and a common gap in comprehension

Based on the academic and practitioner experience of members of the AIR research project team, ongoing analysis and consideration of the presence, property, and protection interfaces between urban underground metro infrastructure (UUMI) and its environment, has been undertaken (Darroch, 2012; 2014; 2020; Darroch et al., 2016; 2018; 2020a; 2020b).

The purpose of the continuing research was to determine how, when, where, and why, the interfaces of UUMI and its environment occurred and how those occurrences affected each other (Fig.3). This was due to the identified common misconception that UUMI is “out of sight” and is therefore “out of mind”. Subsequent outputs from the research saw the production of a dissertation, a thesis, and 5 journal papers to date, on this topic, available online (see bibliography page).

Fig.3: An example of the effect urban underground metro infrastructure can have on its environment, 160 years after its construction, north of Farringdon station, London, UK. Source: Nathan Darroch.

Figure 3 Ray Street Bridge.jpg

The MA dissertation, Darroch, 2012, discussed the historical development of tube railways in London, and the effects and affects that tube railways had and continue to have on their environment and vice versa. The dissertation demonstrated that there is a continuing interconnected and interdependent nature to the presence, property, and protection interfaces of that tube infrastructure and its environment.

Darroch, 2014, presented the initial arguments that the interfaces of UUMI and its environment were essential considerations for urban and transport academics, practitioners, policy makers, and urban stakeholders, to effectively undertake urban change and urban management. To demonstrate the argument, example occurrences of the effects and affects of sub-surface railway and tube-railway UUMI in London, were presented.

Between 2014 and 2019, the ongoing research determined that there was also a paucity of multi-disciplinary (legal, civil engineering, urban and transport planning, asset management, geographical, and historical) analysis and discussion of the occurrences of the interfaces within academic and professional transport and urban management literature, to date, globally.

This was despite the increasing densification of urban environments; proposals for the development of urban underground space (UUS), internationally and the further creation of interfaces of presence, property, and protection interfaces within those urban environments. Fig.4, presents one such example of the interfaces where existing UUMI affected the design the British Library, Euston Road, London (discussed on the Examples UUMI interfaces page).

Fig.4: Section through the British Library showing foundation and building design. Source: Simpson, B., and Vardanega, P., 2014.


The literature review for the research (Darroch, 2020, pp.79-113), determined that the gap in comprehension of the effect and affect of the interfaces, was potentially due to a lack of standardised processes for analysing the occurrences of the interfaces, or for the gathering and publication of key data providing reasoning for their occurrence.

This seeming lack of comprehension was especially apparent through the review of International standards, such as ISO55,000, Asset management (British Standards Institution, 2014), which presumes that asset owners have a clear comprehension of their asset presence, property, and protection interfaces.

The lack of standardised processes for:

  • analysis of the interfaces of infrastructure;

  • gathering of key data relative to the interfaces;

  • verification and validation of data gathered through the analysis; and lack of sharing data within organisations and with interfacing stakeholders.​

To address the lack of a common approach to analysis  and thus comprehension of the interfaces, the 2014-2019 research, saw the development and testing of a conceptual framework (CF) (Fig.5).

Where a conceptual framework is a “theoretical structure of assumptions, principles, and rules that holds together the ideas comprising a broad concept”, WebFinance, 2019). 

Darroch, 2020, (p.30), therefore described the conceptual framework for analysis of the interfaces as "a diagrammatic representation of the primary and subinterfaces/enablers of UUMI and its environment, and how these are interconnected".

Fig.5: The conceptual framework showing the interfaces of UUMI and its environment, and their sub-interfaces/enablers. Source: Darroch, Beecroft, & Nelson, 2016.

Figure 1 The Conceptual Framework.jpg

While the primary interfaces represent overall concepts of what should be considered regarding the interfaces, the nine sub-interfaces/enablers, within the primary interfaces, were to assist clarification of the occurrences of the primary interfaces.

For example, legislation enables the physical presence of example of UUMI within an urban environment and provides requirements to ensure the continued safe continued presence and operation of interfacing infrastructure (future proofing) (Darroch et al., 2016).

To assist the application of the CF to occurrences of the interfaces, several supporting components were developed to assist analysis of the interfaces (Darroch et al., 2018; Darroch 2020, pp.143-163).

These took the form of:

  • depths of analysis (holistic, macro, and micro);

  • what to consider within those depths of analysis (contextual environment to the UUMI;

  • immediate environment of the UUMI;

  • interfaces of the assets forming the UUMI and interfacing urban infrastructure;

  • standardised questions to be applied to the CF and to pertinent data gathered to determine the occurrences of the interfaces;

  • levels of comprehension, which would be achieved from each depth of analysis (appreciation, understanding, knowledge) and which enable effective organisational decision making;a workflow to guide application of the CF during analysis;

  • key findings to be gathered and recorded from the application of the CF to the analysis.

International application of the principles of the conceptual framework

During the 2014-2019 research, the CF was applied to:

  • a pilot study to Glasgow Subway (Darroch et al., 2016);

  •  40 case studies on the London Underground network (Darroch et al., 2018; 2020a; Darroch, 2020, pp.20-236; 248-368) (click this link to see a table of the occurrences identified); and  

  • a questionnaire of Metro organisation members of the Community of Metros and Nova benchmarking group (CoMET, 2020), regarding occurrences of the interfaces on their network (click this link to see a table of findings from the questionnaire);

  • a hypothetical analysis of New York Subway interfacing with the New York Times building, New York, US.

Collectively, these approaches found that the interfaces and their sub-interfaces/enablers, represented by the CF (Fig.4), did not just occur in the UK, but on all surveyed metro systems, internationally (Darroch, 2020, pp.236-247; 368-372).

Hypothetical analysis of the interfaces to other forms of transport and urban infrastructure

To further test the applicability of the CF and the findings of the research, hypothetical analysis of occurrences of the interfaces was undertaken, between (presented on the Interfaces of other infrastructure page):

  • a utilities subway, in Paris;

  • a building over a tramway, in DenHaag, Netherlands;

  • a highway passing through a building in Osaka, Japan; and

  • surface railway infrastructure interfacing with a highway in Hillingdon, Greater London.

From the hypothetical analyses, it was found that the interfaces did not just apply to UUMI or UUS, but to other forms of transport and urban infrastructure (Darroch, 2020, pp.372-385). As with UUMI, occurrences of the interfaces are interconnected and interdependent with their environment and urban infrastructure within that environment.

Fig.6: A tramway in DenHaag, Netherlands, passing through urban infrastructure (a building). The principles of the presence, property, and protection interfaces represented in Fig.5 are just as applicable to this scenario as they are to UUMI. Source: Nathan Darroch.


Findings from the collective research

From the application of the conceptual framework to the case studies of UUMI interfacing with its environment, it was identified that:

  • transport infrastructure and its environment do not exist in isolation, they are interconnected and interdependent;

  • transport and urban infrastructure have many and varied occurrences of the presence, property, and protection interfaces;

  • the interfaces represented within the CF were applicable to all occurrence of the interfaces, internationally;

  • those occurrences have multi-disciplinary factors;

  • the research methodology, processes, and approaches employed in the research, were applicable to all test subjects;

  • multi-disciplinary analysis of the interfaces, has time and cost benefits to metro organisations and their stakeholders;

  • data gathered can be employed to inform Building Information Modelling (BIM) and asset data management processes;

  • that data gathered can save time and cost in asset and urban management processes for infrastructure owning/maintaining organisations and their interfacing stakeholders, locally, nationally, and internationally;

  • the occurrences of interfaces analysed can be employed as guidelines for understanding other similar existing and future occurrences, internationally;

  • standardised benchmarkable processes of analysis and data gathering, publication, and sharing, can assist urban management of the interfaces, internationally;

  • standardised benchmarkable processes of analysis and data gathering, publication, and sharing, can assist the improvement of urban management standards, policies and procedures, internationally.

Further findings from the 2014-2019 research and further gaps in comprehension

While the 2014-2019 research developed a process of qualitative analysis for the interfaces and identified practical benefits to transport and urban infrastructure owners, managers, and policy makers, internationally, it was also found that:

  • the multi-disciplinary analysis of interfaces is currently a little considered topic in current academic, professional, policy-making, transport and urban management disciplines;

  • there appear to be no combined standardised benchmarkable processes of multi-disciplinary analysis, data gathering, publication, and sharing of interface data, to inform accurate BIM and asset data management processes, globally;

  • standardised processes of interface analysis and data gathering to effect that comprehension are not yet commonly employed within organisational, local, national, or international standards for asset and infrastructure proposals, planning, design, construction or subsequent urban management;

  • there is a current and pressing need for practitioners, academics, and policymakers to further enhance the comprehension of the interfaces of urban infrastructure and its environment, as cities globally, densify.

To address the seeming gap in comprehension, discussion, and practical data management of the occurrences of interfaces between urban infrastructure and its environment, the AIR research project was developed.

The outputs of which research are intended to be  developed and tested within participating metro organisations, intentionally. 

Continue to the aims and objectives of the research page.

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