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  • Writer's pictureMark Reiner, PhD, PE

The Risk Velocity of Crumbling Infrastructure

FEMA definition of a hazard: “An act or phenomenon that has the potential to produce harm or other undesirable consequences to a person or thing.” Failed infrastructure certainly can produce harm, but is “crumbling” (aka, aging) an act or a phenomenon? Do officials warn the public to failing infrastructure in the same way as approaching natural hazards?


Typically, the term risk velocity is used in business management as an expression of the time that passes between an occurrence of an event and the point at which the organization first feels its effects. Risk velocity can also be applied to natural hazards, e.g., the time before a hurricane or wildfire is predicted to impact a specific exposed target. However, can risk velocity be applied to the hazards associated with crumbling (aka, aging) infrastructure? It seems counter-intuitive that the answer would be “no”, but as failure is often instantaneous and the threat is already below our streets, the public has no warning. However, it is worth reframing risk velocity for purposes of inclusion in disaster preparedness and focus on breaking down the components of risk velocity – two terms for risk and two terms for velocity.

Risk is the result of a phenomenon or act that causes monetary damage to a thing, or bodily injury to a person. This establishes a two-part causal relationship between the perpetrator of the phenomenon (cause) and the receiver of the damage (effect). With natural hazards, the impacts that result from the cause are often covered under insurance force majeure clauses (e.g., a declaration of war, a disease epidemic, or a hurricane, earthquake, or other natural disaster events that fall under the legal term, “act of God”). However, crumbling infrastructure (cause) is not an act of God, but rather can be traced to a specific utility – that would have some assumed liability. And, while the utility is insured, those local businesses and residents that experience the effect of the cause, are rarely covered by personal insurance (many previous blogs cover indemnification).

The two issues with Risk in crumbling infrastructure are: who is responsible for the cause and what are the cumulative uninsured damages to the effected community?

Velocity is a physics term that is expressed as the rate at which an object changes its position, i.e., change in distance divided by change in time (delta x/delta t). This is easy to visualize with a hurricane or wildfire – how much time before the threat impacts a specific area. The public receives weather/news reports, reverse 911 calls, door to door announcements…etc., and therefore an estimated rate and time until impact. However, velocity does not translate well to crumbling infrastructure. When new infrastructure was placed decades ago, it was never considered a threat, but rather a benefit. The threat evolved as the infrastructure aged in situ (delta x=0) and weakened due to daily stresses and deferred maintenance.

As for the warning period, there are two different values for delta t. One for the utility that owns the crumbling asset and another value for the public. From a utility ownership perspective, there are data regarding the age, condition, and probability/consequences of failure analyses. The goal of these analyses is to determine a delta t that represents a period where the utility can extract as much remaining useful life from the asset under a calculated probability of failure. Thereby maximizing the utility’s economics. But the accepted consequences of asset failure do not consider the full total costs that will Impact the surrounding community.

The other perspective of delta t belongs to the public that use the assets daily, e.g., drive over the bridge, or over the buried water main. They are unaware of this probability of failure period. And, that their insurance may not protect them from the likely consequences of failure. For the public delta t=0. The time associated with failure is the exact time when the asset fails – not when it was expected to fail.

Velocity in the context of crumbling infrastructure, from either the utility’s or the public’s warning interval is zero as delta x=0. The cause is already in-place.

Case Studies

The 2021 ASCE Infrastructure Report Card reports that there are 720 water main breaks per day in the United States. Also, the National Bridge Inventory reports over 45,000 structurally deficient bridges. Of course, most infrastructure failures occur without much impact to the surrounding community due to system redundancy and quick repair responses. But there the occurrences of failures that are called “disasters”, such as the failure of a 96” diameter water main in Houston in February, 2020, that closed an extensive list of businesses and schools. These large community impacts are not uncommon and disaster preparedness should include the discussion of expected recurrence intervals of these failures in planning.

The following three short case studies of failed infrastructure all occurred in the first few months of 2022 and made national news. Each case study is framed to address FEMA’s definition of a hazard, how each failure was referred to as a disaster, and to highlight the instantaneous uninsured risk resulting from the unintended consequences of failure.

Fern Hallow Bridge, Pittsburgh, Pennsylvania: Friday, January 28th, 6:45am

Just hours before President Joe Biden's scheduled speech in Pittsburgh, regarding “crumbling infrastructure” and the $1.2 trillion Build Back Better plan to correct these deficiencies, a bridge collapsed just before rush hour. According to Pittsburgh’s news channel KDKA - Ten people were injured – four of them taken to hospitals – and search dogs were brought in, as were about a dozen NTSB officials, as a chaotic scene began to unfold. Fire Chief Darryl Jones said crews rappelled 100 to 150 feet down the steep hillside in order to help pluck the injured people out of the rubble.

This collapse occurred despite the National Transportation Safety Board finding the bridge in poor condition since 2011, with the latest inspection in 2019, i.e., delta t = 11 years. The city also turned up other needed repairs, but they were not viewed as “as imminent hazards” and were pushed off to future years but do not appear to have been done.

Image 1: Failure of the Fern Hallow Bridge, January 28, 2022 – see footnote.

The impact to the community from the bridge failure then radiated outwards from this single point of failure. KDKA-TV's Bryant Reed reported a strong smell of natural gas in the area. The natural gas main had been cut by the bridge collapse and several families needed to be evacuated from their homes. Pittsburgh Bureau Fire Chief Darryl Jones reported that following the collapse there was a massive gas leak when a line broke, which emitted a sound like a jet engine, on Forbes near South Dallas Avenue. While a local resident stated: “There was a boom, then a monster sound,” said Melissa Bakth, who said she heard the four-lane bridge collapse, followed by the rushing sound of a gas line that broke. Before the end of the day of the collapse, Pennsylvania Governor Tom Wolf signed a disaster emergency proclamation for Allegheny County.

Kingsessing neighborhood, Philadelphia, PA, Wednesday, February 9th, 6:42am

Philadelphia officials reported that a 48-inch water main break occurred at the intersection of 56th Street and Springfield Avenue just before rush hour on February 9th, 2022. The break sent roughly eight million gallons of water into the streets of the Kingsessing neighborhood, leading to evacuations of houses, the closure of 16 schools, and the shut-off of natural gas and water shut off over entire neighborhood. First responders conducted door to door searches and rescued 6 people from flooded basements. SEPTA buses were brought in to provide shelter to those who needed to evacuate. News reports showed that the Kingsessing neighborhood had transformed into a temporary river. Many of the cars on the block were trapped as crews worked to assess the situation.

Figure 1: 3D representation of average daily traffic before (left) and after (right) water main break. Courtesy of StreetLight Data

The 3D image in Figure 1 represents average daily traffic on a normal weekday just prior to the water main break (left) and the impacts to traffic across the neighborhood following the water main break (right). Consider what other impacts occurred across this area, e.g., loss revenue and wages from local businesses, travel delays and associated emissions, and loss of natural gas heating during frigid winter months. A failed asset might be a point location, but the community impact is a much larger polygon.

As to reoccurrence intervals that we are familiar when discussing large precipitation events, e.g., the 100-year flood, consider this quote: "Philadelphia, built on a network of 3,100 miles of aging water infrastructure, is no stranger to breaks in its mains. On average, the city experiences about 776 water-main breaks per year, with large bursts like the one in Kingsessing happening once or twice annually, a water department spokesperson said. In a letter to Governor Wolf, Reps. Dwight Evans and Mary Gay Scanlon, both Democrats from Southeastern Pennsylvania, wrote that “a swift response is essential to provide support to Kingsessing and the families affected by this disaster,…”.

Odessa, Texas: Monday, June 12th, 6:00 pm

According to Odessa Mayor Javier Joven, the water main break occurred at 6 p.m. Monday, June 12th near Tom Green Avenue between 42nd and San Jacinto streets. During a news conference Tuesday, Tom Kerr, the city’s utilities director, said the line that broke is about 60 years old. “Aging water systems are common throughout the country,” Kerr said. “It’s often difficult for municipalities to be able to afford to manage those systems as they age. That’s the situation we find ourselves in.”

The break left about 165,000 people without water in Odessa and some surrounding areas. The city suddenly lost the ability to open their taps for basic household functions such as drinking, cooking, cleaning and toilet use. The water break could not have happened at worse time for Odessa, as temperatures soared in an early summer heat wave. There's an "imminent threat" of "severe damage, injury, or loss of life or property", according to a declaration of disaster from the Ector County Office of Emergency Management. On a personal community level, Nikki Buchanan stated her concerns: “I have a 4-month-old at home, and I need a way to wash my bottles and my pump to breastfeed,” Buchanan said. “I had to throw out the milk I had pumped, which was very upsetting for me because I could’ve used that for my baby.

By Wednesday, June 14th, Texas Governor Abbott directed state agencies, through the Texas Division of Emergency (TDEM), to coordinate and deploy resources in response to a disaster declaration issued by Ector County Judge Debi Hays resulting from the City of Odessa main water line failure. While the water utility saw the point of impact to their system at Tom Green Avenue between 42nd and San Jacinto streets, the community saw a water, economic, and health impact city-wide.


Although just three case studies are included in this blog, these events are very common across the United States and across all seasons. Occurring far more frequently than the return period of natural hazards. In fact, a major water main break occurred near me just last month. The goal of this blog is to introduce more terms that frame crumbling infrastructure into the hazard discussion, and recognize that more can be done to evaluate a community perspective of the potential hazards prior to failure. Although addressing the impacts of flooding, this quote from Pennsylvania Governor Wolf is on target for community inclusion and the point failure characteristic of failed infrastructure.

“Evaluating impacts solely on a micro level at the municipal or county level alone, rather than toward a whole state assessment, would provide a more realistic assessment of the impacts to that community… Doing so will provide much needed direct assistance to the most vulnerable who most often are ineligible for other disaster assistance.”
– Gov. Tom Wolf

Changing the risk velocity of crumbling infrastructure requires that the senior staff and elected officials of a city can act as empowered utility stakeholders, with their own information. The first steps in this evolution are to proactively develop the key performance indicators of infrastructure disruption into a common vernacular commonly used by the Public Works Director, Senior Planner, and Emergency Management. This requires a comprehensive methodology for determining and quantifying when/where failed infrastructure would be “disruptive” to communities within the city. Consider this statement from the Mayor of Hoboken, New Jersey during the summer of 2018:

Good morning, I am here today to brief the public on the unacceptable rash of water main breaks that have occurred in Hoboken since June 23rd. In total we have experienced 14 water main breaks over a 64-day period, with two breaks occurring as recently as yesterday. Never before have we seen such a string of major breaks in our city; particularly during the summer months. … First, in order to expedite our ability to thoroughly investigate, and permanently resolve, the threat to the health, safety and welfare of our residents caused by these breaks, the city is declaring an emergency under Section 60-11 of the City Code.
- Mayor Bhalla, Hoboken, NJ

As more infrastructure assets fail, public opinion can be detrimentally affected and directed towards city-leadership, regardless of which entity is to blame. Without quantifying the costs burdened by the community following asset failures, i.e., social costs, how can cities really discuss the "true cost" of infrastructure.


The credit to the image of the bridge collapse at Frick Park, PA. is Bloomberg via Getty Images. It is used under terms of fair use as this is an informative blog that is not monetized and no claims of copyright are intended.

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