Defeating disaster

December 2013 » Features » PROGRESSIVE ENGINEERING
A wide range of planning, infrastructure, and design strategies can be used to engineer more resilient cities.
Mickey Sullivan, P.E.
A bioswale median on Nashville's 28th-31st Avenue Connector helps to filter stormwater runoff.
Photo: Aaron Matheson

Whether in person or on television, whether witnessing massive flooding in Colorado, devastating tornadoes in Oklahoma, or the swath of destruction cut by Superstorm Sandy, we have all seen the havoc that natural disaster can wreak on lives, communities, and properties. We have heard, too, that climate change could worsen that damage and increase the occurrence of atypical weather events. Having seen and heard these things, the real question is, what are we going to do about it? How can we, as planners and engineers, use our skills to ensure that our communities are prepared and their citizens are as safe as possible?

Resilience engineering offers one answer to that question. In its 2013 infrastructure report card, the American Society of Civil Engineers (ASCE) defines resilience as a system's "capability to prevent or protect against significant multi-hazard threats ... expeditiously recover, and reconstitute critical services with minimum damage to public safety and health, the economy, and national security" (ASCE, 2013). More simply, I would also define it as choosing action over reaction. Each time we design a new project, update a municipal plan, or write new building codes and zoning ordinances, we have a chance to take action and build in safeguards against future disaster. To be most effective, this action should be both fine-grained and universal, integrated into projects large and small, across disciplines and throughout a city.

Local weather data provides the perfect starting point. A 2009 U.S. Global Change Research Program report mapped the effects of climate change on regional weather. It predicted more heavy downpours and flooding in the Northeast, both severe flooding and severe drought in the Midwest, more severe tornadoes and hurricanes in the Southeast, increased wildfires and coastal erosion in the Northwest, and severe drought interspersed with unexpected flooding in the Southwest (see Figure 1). Overall, the occurrence of randomized, heavy precipitation events was predicted to skew upwards from historical averages (Karl et al., 2009).

This upward trend in non-average, unpredictable weather events poses a fundamental problem for designers and engineers, who typically base designs on predictions drawn from historical weather data. Climate change, and its volatile effect on weather patterns, is pushing the limits of that data set and challenging designers to think beyond precedent. A failure to seek out current data and account for projected changes could result in designs that stand up perfectly well to "traditional" weather, but falter when faced with new or more severe patterns.

Figure 1: Predicted effects of climate change on regional weather.
Source: Gresham, Smith and Partners, based on U.S. Global Change Research Program

Aside from broad reevaluation of data, a wide range of planning, infrastructure, and design strategies can be used to engineer more resilient cities, with good, responsible design as the first line of defense.

Resilient planning
Nearly every aspect of city planning can play a role in increasing a city's resilience across a broad cross-section of initiatives.

Site selection – Relocate fire stations, police stations, water utilities, schools, and other key infrastructure as far from the floodplain as possible. Some cities have converted low-lying areas into public parks, providing a nice amenity while restricting key services to higher ground.

Emergency protocols – Double-check emergency protocols for accuracy and efficacy. Ensure that emergency contact databases are up-to-date and set up regular drills to avoid complacency and identify weaknesses. Review public shelter offerings, schools, and other buildings that can double as high-capacity shelters when disaster strikes. Equip these designated buildings with easily accessible basements, reinforced walls, and other safeguards to minimize casualties.

Building codes and zoning ordinances – Evaluate codes and ordinances to determine if they assist or impede resilience engineering measures. Consider updating codes to automatically integrate resilience engineering in future plans.

Continual evaluation – Resilience is all about adaptation, and resilient systems should constantly evolve based on lessons learned from each disaster event. Make evaluation and reevaluation a priority.

Rain gardens and bioswales near Vanderbilt's 100 Oaks Medical Center mitigate flooding by capturing and slowly filtering rainwater.
Photo: Bob Schatz
Floodwaters partially submerged a key water treatment plant in Nashville.
Photo: Gresham, Smith & Partners

Resilient infrastructure
Resilience engineering should become the modus operandi for infrastructure development, with the goal of creating systems that can proactively adapt to non-normal situations.

Transportation systems – Identify key evacuation routes, determine if capacity is appropriate for large-scale evacuation, and develop contingency plans for transforming those routes into one-way pathways away from disaster. Invest in dynamic electronic message boards to communicate real-time messages to the public when time can save lives. Install redundant communication and power systems, especially in crucial locations such as airports, which depend on a real-time data stream.

Stormwater management – Re-evaluate rainfall statistics to determine if key sites can accommodate increased precipitation. Consider using rain gardens, bioswales, or permeable pavement to mitigate flooding along transportation corridors. More site-specific solutions, such as grooved airport runways, should also be evaluated.

Water systems – If sewers are in disrepair, stormwater can seep in during heavy rainfall and cause sanitary sewer overflows. Comprehensive sewer rehabilitation efforts can minimize this risk by routinely evaluating sewer systems, replacing worn pipes and liners, and testing manholes and other entry points for leakages. In addition to reducing overflows, these measures can manage costs by minimizing the amount of water needing treatment.

Power systems - As most of us know too well, above-ground power lines are very vulnerable to weather events, even moderate thunderstorms. Installing and relocating power lines underground can help prevent outages.

Resilient buildings
Resilient strategies can be built into any structure, and even small steps can make a big difference when disaster strikes.

Resilient water treatment plants – In 2010, Nashville, Tenn., suffered severe flooding and its central K.R. Harrington Water Treatment Plant was forced completely out-of-service. Gresham, Smith and Partners was charged with getting the plant online, and later, with incorporating measures to prevent future problems. These included elevating plant power systems and switchgears to keep them running during a flood.

Resilient hospitals – Perhaps more than any other building, it is critical that hospitals remain operational during disasters. As with water treatment plants, elevate key functions to prevent flood damage. For example, Tampa General Hospital located its Emergency Department on the second floor. Where elevation is not possible, upper-floor rooms should be designed as "flex spaces." Designers of St. Bernard Parish Hospital, rebuilding a facility destroyed during Hurricane Katrina, created adaptable spaces on the hospital's upper floors that could convert to emergency treatment areas with little notice and remain functional during disaster.

Equipping waiting areas, conference rooms, and administrative areas with locked medical gas cabinets can help accommodate patient overflows. At Tampa General, even the parking garage is multi-purpose, designed to become a triage area in the event of a major catastrophe. Central energy plants and other critical building systems, such as air-handlers, pumps, and elevator equipment, should also be located either on upper floors or on rooftops. However, rooftop equipment should be durable enough to withstand water and wind damage.

An elevated central energy plant helps to safeguard operations at St. Bernard Parish Hospital.
Photo: Rob Pepple

Secure buildings – In both public and private buildings, good design can guard against a wide range of threats. This does not necessarily mean putting bars over every window – there are a number of subtle strategies that can protect a building's occupants. For example, exterior courtyards, bollards, or planters create an attractive building perimeter and serve the dual purpose of keeping vehicles a safe distance away. In the event of a tornado or flood, this buffer can help minimize damage from wayward vehicles and other debris. Again, key building functions should be elevated to minimize damage, and connectors or other structural elements reinforced to withstand extreme loads.

The emergency department at Tampa General Hospital is located on the second floor to guard against flooding.
Photo: Rion Rizzo

This is certainly not a comprehensive list, but it is a good start. Without a doubt, many of these changes bring considerable costs. However, when dealing with natural disaster, the cost of inaction can be tremendous, not just in dollars, but in lives, businesses, and homes. Investing in resilience engineering now can help mitigate the costs of future disasters. In fact, one statistic from the Center for American Progress shows that every $1 invested in disaster resiliency will save $4 in future recovery costs (Weiss and Weidman, 2013).

The need for such investment is great, and the time is ripe. In the ASCE's most recent report card, American infrastructure received an overall grade of D+. Considering that abysmal grade, there is currently significant public and political interest in funding infrastructure improvement. The most prudent use of that funding would couple standard infrastructure upgrades with investments in resilience engineering to improve the performance of our infrastructure in everyday situations and during disasters. We have a window of opportunity, and now is not the time for inaction. It is the time to decide how we would like to be remembered – as a generation of engineers mired in inaction or as a generation prepared to take tough action today to make our cities safer and more resilient in the challenges of tomorrow.

References

Mickey Sullivan, P.E., is regional vice president with Gresham, Smith and Partners.

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