The National Academies Press

Currently Skimming:

Pages 19-44

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.

From page 19... ... 19 The increasing threat that natural hazards pose to the nation's transportation infrastructure and mobility varies by region and by mode. To boost transportation resilience, policy makers and infrastructure decision makers need a solid understanding of the specific hazards that the transportation systems under their purview face. Read the entire page →
From page 20... ... 20 INVESTING IN TRANSPORTATION RESILIENCE for inflation, averaged only 2.9 per year. By the 2010s, the average reached $11.9 billion in disasters per year. Read the entire page →
From page 21... ... AMERICA'S TRANSPORTATION INFRASTRUCTURE 21 greenhouse gases.8 For roads, both the Assessment's high-emission and lowemission scenarios show increased costs, cumulatively up to an additional $230 billion through 2100, just to repair damage attributed to changes in temperature, precipitation, and freeze-thaw cycles. For bridges, the primary danger is scour, where the flow of water undermines the integrity of the bridge piers. Read the entire page →
From page 22... ... 22 INVESTING IN TRANSPORTATION RESILIENCE concludes with a discussion of the role of federal investment in providing data for hazard modeling and projections. TO BUILD RESILIENCE -- FIRST, UNDERSTAND THE HAZARD All approaches to evaluating resilience to inform transportation investment decisions require knowledge of the natural hazards. Read the entire page →
From page 23... ... AMERICA'S TRANSPORTATION INFRASTRUCTURE 23 programs, which develop and utilize this knowledge, are vital for integrating resilience into transportation decision making. Asset management is a strategic and systematic process of operating, maintaining, and improving physical assets. Read the entire page →
From page 24... ... 24 INVESTING IN TRANSPORTATION RESILIENCE Meteorological Hazards Meteorological hazards are commonly called bad weather: hurricanes and other storms with high winds, heavy rain or snow, and intense lightning; heat waves and severe cold snaps; and drought. High winds can occur during major storms such as hurricanes and nor'easters, as well as more localized windstorms such as tornadoes. Read the entire page →
From page 25... ... AMERICA'S TRANSPORTATION INFRASTRUCTURE 25 melting permafrost.14 These chronic changes in the natural environment, which are happening today and are expected to be exacerbated by climate change, can alter the context under which transportation operates. Such hazards may affect transportation directly or they may interact with meteorological and geological events, affecting their frequency and severity. Read the entire page →
From page 26... ... 26 INVESTING IN TRANSPORTATION RESILIENCE outlet. Since 1964, the water level of the lake has risen by 13 meters, the area of the lake has expanded by 10 times, and the volume of water in the lake has expanded by 32 times. Read the entire page →
From page 27... ... AMERICA'S TRANSPORTATION INFRASTRUCTURE 27 FIGURE 2-1 Average annual temperature change for the contiguous United States from the 1981–2010 climate normals to the newest data in the 1991–2020 normals.22 Hazards Vary by Region and Location Meteorological and geological hazards and the effects of climate change vary by region and location. Resilience analysis, planning, and management processes need to account for this variation. Read the entire page →
From page 28... ... 28 INVESTING IN TRANSPORTATION RESILIENCE FIGURE 2-2 Expected frequency of earthquake occurrences in the United States.23 and hail appear in every state. Mountainous regions create the conditions for landslides and rockfalls. Read the entire page →
From page 29... ... AMERICA'S TRANSPORTATION INFRASTRUCTURE 29 FIGURE 2-3 Number of flood events reported for a county or zone in New York 1996–2019.25 FIGURE 2-4 Number of flood events reported for a county or zone in California 1996–2019.26 25 FEMA. Read the entire page →
From page 30... ... 30 INVESTING IN TRANSPORTATION RESILIENCE interactive data tool, which presents historical flood risk using data from 1996 to 2019.27 Increases in the Frequency of Extreme Weather Events Climate change can lead to shifts in extreme weather, and trends indicate that large areas of the United States are being subject to such extremes. Because conventional design, material, and operational standards in transportation are built around historic weather data, increases in the likelihood of a hazard can turn a distant threat into an imminent disaster. Read the entire page →
From page 31... ... AMERICA'S TRANSPORTATION INFRASTRUCTURE 31 Management Agency (FEMA) defines a "base flood" as "a flood having a one percent chance of being equaled or exceeded in any given year." FEMA's base flood also has a metric for flood elevation.29 Measuring Likelihood Measuring likelihood is an integral step to producing the scenarios required for most approaches to resilience analysis. Read the entire page →
From page 32... ... 32 INVESTING IN TRANSPORTATION RESILIENCE 50 years.) Furthermore, each level is tied to a performance goal. Read the entire page →
From page 33... ... AMERICA'S TRANSPORTATION INFRASTRUCTURE 33 Examples of Measuring Exposure and Likelihood The U.S. Department of Transportation's (U.S. Read the entire page →
From page 34... ... 34 INVESTING IN TRANSPORTATION RESILIENCE HAZARD CHARACTERIZATION The significance of a natural hazard depends not only on how likely it is to occur but also on how serious and widespread its effects are likely to be. Resilience analysis, therefore, must also incorporate knowledge about how specific natural hazards interact with specific transportation assets (including nodes, networks, and systems) Read the entire page →
From page 35... ... AMERICA'S TRANSPORTATION INFRASTRUCTURE 35 For flooding or storm surge, spatial analysis usually focuses on the area inundated and the depth of the water.41 Spatial analysis of hazard effects also must include the geographic extent of the transportation system under study and capture disruption to nodes and network links, as well as infrastructure assets. Duration of the Hazard Event Hazard characterization includes the entire arc of time from first warning to when the event is no longer actively producing effects. Read the entire page →
From page 36... ... 36 INVESTING IN TRANSPORTATION RESILIENCE forecasting, by contrast, is much more limited. Earthquake "shaking" alert systems can only provide seconds of warning. Read the entire page →
From page 37... ... AMERICA'S TRANSPORTATION INFRASTRUCTURE 37 only characterize all relevant hazard events but also analyze the potential for events to occur simultaneously or in quick succession. Multiple-hazard analysis evaluates the effects of two or more separate hazard events, as opposed to looking at the multiple effects of a single event. Read the entire page →
From page 38... ... 38 INVESTING IN TRANSPORTATION RESILIENCE Deterministic and Probabilistic Methods The deterministic approach chooses a set of hazard scenarios that could affect the transportation asset or system. Using methods specific to the type of hazard, the approach generates the loadings from each scenario and chooses the one that presents the worst case. Read the entire page →
From page 39... ... AMERICA'S TRANSPORTATION INFRASTRUCTURE 39 this shortcoming involve generating a set of realistic loading scenarios that correspond to approximately the same hazard level.50,51 The time-based approach requires generating the spatial distribution of loading intensity for all events that could impact the region of interest over a specific time horizon. The time-based approach, which is also used by the insurance industry, is the most complex, and its application in transportation is currently limited to research. Read the entire page →
From page 40... ... 40 INVESTING IN TRANSPORTATION RESILIENCE FEMA Flood Maps FEMA produces maps of flood hazards to serve the National Flood Insurance Program (NFIP) and the associated regulatory requirements for county-level flood zone management. Read the entire page →
From page 41... ... AMERICA'S TRANSPORTATION INFRASTRUCTURE 41 FIGURE 2-5 Unmapped stream miles by county, as of fiscal year 2019.57 FIGURE 2-6 Difference in number of properties at substantial flood risk compared to FEMA's data.58 57Association of State Floodplain Managers. Read the entire page →
From page 42... ... 42 INVESTING IN TRANSPORTATION RESILIENCE Atlas 14 Atlas 14 is the most recent edition of a database produced by NOAA's Hydrometeorological Design Studies Center that provides detailed precipitation frequency data for most regions of the United States. Although Atlas 14 is used at the federal, state, and local levels for planning activities, engineering design, modeling of flood risks, and managing floodplain devel opment for NFIP, its data are out of date. Read the entire page →
From page 43... ... AMERICA'S TRANSPORTATION INFRASTRUCTURE 43 a four-state effort to update Atlas 14's precipitation estimates. Updated data are essential to support accurate estimates for what communities can expect from storm events; for Commonwealth agencies to have accurate forecasting projections to prepare for future rain, storm, and other climatic events; and to ensure accurate regulatory processes. Read the entire page →

From page 19...

... 19 The increasing threat that natural hazards pose to the nation's transportation infrastructure and mobility varies by region and by mode. To boost transportation resilience, policy makers and infrastructure decision makers need a solid understanding of the specific hazards that the transportation systems under their purview face.