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  • Writer's pictureMark Reiner, PhD, PE

Decaying Infrastructure as a Hazard and part of City Resilience Planning

Updated: Sep 24, 2019

The most accepted definitions of resilient infrastructure do not encompass a significant urban threat – chronic decay due to deferred maintenance and hurried construction. Likewise, resilient cities have not defined how failed infrastructure ‘disrupts’ city economic and social life nor quantified the associated true costs. In order to establish a foundation for a smart and resilient city, urban planning must adopt a methodology for defining critical areas in a city that should not be disrupted.

Despite perpetual urban road construction to fix, repair, and replace infrastructure assets, city resilience and smart planning rarely quantifies the resulting chronic social and economic disruption impacts. In New York City (population 8.6 million), the streets are sliced open 200,000 times per year, an average of almost 550 cuts per day, to facilitate buried infrastructure repairs, replacements, and new construction [1]. For purposes of scale, Arvada, Colorado (population 119,000) – my hometown and data acquired by an open records inquiry – experiences an amazingly proportional 8 road cuts each weekday. And, without changing the RABID paradigm (Roads and Buried Infrastructure Decay from Part 1), there is no reason to expect that the rate of infrastructure decay and associated road closures will not increase.

This is due, in part, to the fact that the chronic decay of infrastructure has not been properly classified as a hazard. In fact, even the U.S. Federal Emergency Management Agency’s (FEMA’s) Hazard Mitigation Planning (HMP) process for communities does not include aging infrastructure as a hazard [2]. The HMP only requires communities to address natural, manmade (vulnerabilities of systems to terrorism), and technological (nuclear power plant incidents and U.S. Army chemical stockpiles) hazards [3].

One reason for this omission is that the common definition of resilient infrastructure is based on acute shocks that a system should absorb, quickly recover, or ‘bounce forward’. This view is included in the most common definition for resilient infrastructure: “…the ability to plan and prepare for, absorb, recover from, and adapt to adverse events” [4]. But this view of "events" ignores the chronic threat of decay. That is, resilient infrastructure must function under the shock of natural disasters and the chronic threat of decay. In the United States, there are over 650 water main breaks per day [5] and the main causes of failure are corrosion and hurried construction (explained further in Part 3). Natural disaster is not even listed as a significant contributor to these breaks [6, 7]. Therefore, the deferred maintenance caused by inaccessibility due to the RABID paradigm is not properly qualified as a threat.

A common perspective of infrastructure risk is: Risk = Asset + Threat + Vulnerability. While it may be common practice to view deferred maintenance of infrastructure assets as a key cause of vulnerabilities (correctly so), it is not common to view deferred maintenance as also the actual threat. Rather, the infrastructure risk is attributed to the threat of natural hazards and construction accidents. But when does deferred maintenance move from being the cause of vulnerabilities to being the actual threat to our infrastructure assets? Deferred maintenance caused by the inaccessibility of the RABID paradigm is the major threat to urban infrastructure that should be discussed in urban resilient/smart planning – but is generally not.

RABID and City Resilience

Consider the City of Boston’s resilience plan – Resilient Boston: An Equitable and Connected City [8]. In the second paragraph of Mayor Martin J. Walsh’s introductory letter, he states:

We are addressing our most serious shocks, such as extreme weather events, and our chronic stresses, such as economic inequality and aging infrastructure.

In one sentence, Mayor Walsh correctly states that the threats to city resilience are both shocks (acute) and chronic. But despite identifying “aging infrastructure” as a chronic threat, the term is only mentioned one other time (bottom of page 128) in the entire document as a reference to the 311-phone service where citizens can complain about aging infrastructure. Rather, the term “aging transportation infrastructure” is discussed throughout the report without the connection to the underlying (or, overhead) infrastructure. The reasons for this omission are at least two parts: 1) no methodology for simplifying and discussing the condition of all infrastructure sectors in areas of a city; and 2) not differentiating acute ‘shocks’ coming from natural hazards from the slow decay of chronic deferred maintenance.

Simplifying the combined condition of multiple sectors of infrastructure into a letter grade over an area has been applied at the national level. The American Society of Civil Engineering (ASCE) has issued quadrennial reports since 1998 – Infrastructure Report Card (Report Card) – that comments on the status of infrastructure in the United States [5]. The Report Card issues a single letter grade for the entire United States – “D+” – derived by averaging the grades of 16 categories of infrastructure. But this national level methodology of averaging grades does not account for the physical hazards of collocating assets in close proximity under our urban roads, i.e. RABID.

For example, a freshly paved urban road may receive a letter grade of “A+”, while just below the surface is a large-diameter, 130-year-old cast-iron water main that might receive an “F” grade. Still below the same road section are natural gas, buried electric, and communications assets that each received “C” grades. Averaging these sectors would result in an overall grade of “C” for this road segment. But, on a paradigm level, the grade for an urban intersection should reflect the threat of the asset that could cause physical disruption (these are assets that are structural, e.g. a bridge, or under pressure, e.g. a water main) [9]. Therefore, the intersection could be graded by the asset that poses the greatest threat to disrupting city life, i.e. the water main. By grading at the RABID paradigm level, this road segment should receive an “F” until the threat from the decaying water main has been replaced. The two photos in Figure 1 represent the victor in the battle between new pavement and a failed water main (on left) and a critical urban intersection that should not be disrupted (on right).

Figure 1: Threats of Collocating Infrastructure Assets for Determining Grades (obtained via Google image search)

To better integrate the RABID paradigm in city resilience and smart planning, and to establish a foundation for discussing paradigm change in certain corridors of a city, key performance indicators (KPIs) must document the economic impact of RABID from a city-centric point of view. This begins with a broad categorization of threats to urban infrastructure as either:

- Chronic disruptions: This is represented by daily disruptions due to infrastructure maintenance, repair/replacement: traffic delays, detours, loss of business…etc. And, the indirect costs that a city shoulders without quantifying (discussed in Part 4).

- Acute disruptions: This includes non-frequent shocks to infrastructure causing failures that include FEMA’s HMP categories of natural disaster, manmade, and technological. The key driver in the discussion of natural disasters being primarily climate change (aka, non-stationarity).

Further details regarding these KPIs are discussed in Parts 3 through 5.

The Previous and Next Parts to this Blog Include:


[2] Reiner, M.; Rouse, D. Dependency model: Reliable infrastructure and the resilient, sustainable, and livable city. Sustain. Resilient Infrastruct. 2017, 9689, 1–6, doi:10.1080/23789689.2017.1386041.

[4] The National Academies. (2012). Disaster resilience: A national imperative. Washington, D.C.: National Academies Press.

[5] Derived from: ASCE's 2017 American Infrastructure Report Card | GPA: D+. (2019). Retrieved from

[6] Folkman, S. (2018). Water Main Break Rates in the USA and Canada: A Comprehensive Study. Mechanical and Aerospace Engineering Faculty Publications, Paper 174. Retrieved from

[7] Climate change is the most major threat to the world, but in terms of threats to urban infrastructure, decay needs to be considered equally as a threat. In addition, natural disasters do not endanger infrastructure equally. The Transition needs to be considered, e.g. wildfires endanger high voltage transmission lines, but rarely buried water mains.

[8] City of Boston, Mayor's Office of Resilience and Racial Equity, 2019. Retrieved from:

[9] Reiner, M., & McElvaney, L. (2017). Foundational infrastructure framework for city resilience. Sustainable And Resilient Infrastructure, 2(1), 1-7. doi: 10.1080/23789689.2017.1278994

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