Strategic Issues Facing Transportation, Volume 2: Climate Change, Extreme Weather Events, and the Highway System: Practitioner’s Guide and Research Report (2014) / Chapter Skim
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P a r t I Practitioner's Guide
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3 Extreme weather events, hurricanes, tropical storms, and prolonged intense temperatures have heightened awareness of a changing climate. Even for those who are skeptical about the long-term effects of this change, there is strong evidence to suggest that these extreme weather events are occurring more frequently, with the need for state transportation agencies to respond to the aftermath.
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4 Strategic Issues Facing Transportation Step 7: Coordinate agency functions for adaptation program implementation (and optionally identify agency/public risk tolerance and set trigger thresholds)
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Climate Change, Extreme Weather Events, and the Highway System: Practitioner's Guide 5 and the overall goal of the study. The main tools used to simulate global climate and the effects of increased levels of greenhouse gases (GHGs)
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6 Strategic Issues Facing Transportation Climatic/ Weather Change Impact to Infrastructure Impact to Operations/Maintenance Temperature Change in extreme maximum temperature Premature deterioration of infrastructure. Damage to roads from buckling and rutting.
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Climate Change, Extreme Weather Events, and the Highway System: Practitioner's Guide 7 Climatic/ Weather Change Impact to Infrastructure Impact to Operations/Maintenance Increased intense precipitation, other change in storm intensity (except hurricanes) Heavy winter rain with accompanying mudslides can damage roads (washouts and undercutting)
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8 Strategic Issues Facing Transportation 3. What is the risk to the asset and to the affected environment given expected changing climatic conditions?
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Climate Change, Extreme Weather Events, and the Highway System: Practitioner's Guide 9 Climate change and the associated increase in extreme weather is an increasingly important factor in this estimation. With respect to culverts, for example, as increasing financial, regulatory, and demand maintenance factors make it increasingly difficult to inspect and maintain culverts, the increasing risks due to climate change are exacerbated.
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10 Why Is This Guide Needed? The climate is changing and, according to the latest climate modeling, is projected to continue changing at an increasingly rapid pace over the coming decades.
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Introduction and Purpose 11 What Is Adaptation? A number of organizations have sought to define the concept of adaptation.
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12 Strategic Issues Facing Transportation Who Should Read What? This guide is organized to allow readers to focus on the adaptation issues of most interest.
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Introduction and Purpose 13 • Chapter 5 presents approaches and methods for considering the risk to infrastructure of changing climatic conditions and extreme weather events, one of the key challenges in adaptation planning. Risk to infrastructure has been repeatedly identified by practitioners as one of the most difficult tasks in adaptation planning.
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14 How should a transportation agency assess and adapt to the challenges of climate change? This question is becoming more important as extreme weather events occur more frequently and more transportation agencies come to believe that these events go beyond normal climate variability.
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Framework for Adaptation Planning and Strategy Identification 15 policies as well as testing alternative management practices designed to address new and uncertain conditions. An adaptive systems management approach to transportation infrastructure management provides a structured framework for characterizing future risks and developing new and evolving strategies to minimize system risk over time.
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16 Strategic Issues Facing Transportation The framework then determines the likely future climatic and weather conditions. In other words, if the goal is to develop strategies to protect assets from higher-than-normal environmental stresses, there has to be some sense of what these stresses are likely to be.
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Framework for Adaptation Planning and Strategy Identification 17 Step 2: Define Policies on Assets, Asset Types, or Locations That Will Receive Adaptation Consideration Changes in climate can affect many different components of a transportation system. Depending on the type of hazard or threat, the impact to the integrity and resiliency of the system will vary.
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18 Strategic Issues Facing Transportation The United States Geological Survey (USGS) and other government agencies are in various stages of producing downscaled climate data -- that is, data at more disaggregate levels (such as an 8 mile by 8 mile grid cell)
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Framework for Adaptation Planning and Strategy Identification 19 The State of California, for example, has performed an assessment of its vulnerability to coastal flooding, including vulnerability of its transportation infrastructure. The vulnerability assessment utilized flood mapping studies from the Scripps Institution of Oceanography and probability calculations of 100-year flood events.
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20 Strategic Issues Facing Transportation In the diagnostic framework (Figure I.2) , there is the possibility of proceeding directly to the identification of design or other solutions (Step 8)
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Framework for Adaptation Planning and Strategy Identification 21 research on the response of materials, soils, and structures themselves has led to a better understanding of the factors that can be incorporated into engineering design to account for such extreme events. Similarly, other design contexts reflect forces that might be applied during collisions, fires, or heavy snows.
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22 Strategic Issues Facing Transportation procedures to changes in construction practices. If the focus of the adaptation assessment is on specific assets in a particular location, more detailed engineering site analyses might be needed.
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Framework for Adaptation Planning and Strategy Identification 23 competitiveness, community quality of life, public health, etc. Goals and objectives further define how the vision will be accomplished.
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24 Strategic Issues Facing Transportation Scenario Analysis to Determine Vulnerable Populations to Sea-Level Rise on Cape Cod Three federal agencies -- the Federal Highway Administration, National Park Service and the U.S. Fish and Wildlife Service -- sponsored a scenario-planning effort on Cape Cod, one of the nation's most ecologically sensitive areas.
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Framework for Adaptation Planning and Strategy Identification 25 Institutional, Financial, and Political Obstacles The diagnostic framework in Figure I.2 mirrors the thought process that transportation agencies are using around the world in adaptation planning. However, this framework focuses on the technical aspects of adaptation planning, whereas many of the state officials participating in the testing of this framework noted practical institutional, financial, and political issues.
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26 Strategic Issues Facing Transportation Figure I.4. Guide organization based on diagnostic framework.
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27 C H A P T E R 3 Determining the types and potential magnitudes of changes in climate that could affect transportation systems is one of the most important early steps in the diagnostic framework. Such information can be used in efforts to increase the robustness and resilience of transportation systems to changes that might represent threats to infrastructure and system operations.
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28 Strategic Issues Facing Transportation research, which can estimate changes in GHG concentrations, average global temperatures, and sea levels. Multiple models are usually used, all guided by IPCC-specified parameters.
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Projected Changes in the Climate 29 Scenarios (SRES) ; Nakicenovic et al.
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30 Strategic Issues Facing Transportation values, while the higher A1FI scenario results in a 4.1°C (7.4°F) increase, a factor of 2.7.
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Projected Changes in the Climate 31 (560 ppm) , resulting in an estimate of how much average global temperatures will increase.
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32 Strategic Issues Facing Transportation Pacific Northwest dry. During so-called "La Niña years" (when those sea surface temperatures in the tropical Pacific are cooler than normal)
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Projected Changes in the Climate 33 While all U.S. regions are projected to increase in temperature, the amounts will vary by location and season.
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34 Strategic Issues Facing Transportation will increase with higher temperatures (because as air warms it can hold more water vapor) , it is not the case that all areas will get more precipitation.
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Projected Changes in the Climate 35 precipitation change from the model results. It may be best to look at regional areas in this figure and not focus on what is happening in specific states or localities.
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36 Strategic Issues Facing Transportation of what are now considered extreme temperatures, such as days above 32°C (90°F)
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Projected Changes in the Climate 37 will be even stronger (Emanuel et al. 2008; Knutson et al.
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38 Strategic Issues Facing Transportation 2009)
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Projected Changes in the Climate 39 Bias-Corrected Statistical Downscaling It is generally not a good idea to use raw GCM output directly as an estimate of climate change. Typically change in climate as estimated by GCMs is used.
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40 Strategic Issues Facing Transportation about how precipitation can change, then it should use scenarios that capture a wide range of potential changes in precipitation. Timeframe Climate conditions over approximately the next two to three decades will most likely be dominated by natural variability, whereas more than three decades into the future, the "signal" from human-caused climate change will most likely emerge from the "noise" of natural variability.
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Projected Changes in the Climate 41 Climate Models It is not advisable to use just one climate model. For a given emissions scenario, a model only gives one projection of change in climate, which can be misinterpreted as a forecast.
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42 This chapter identifies potential climate change impacts on highway systems and on the natural environment, and the possible strategies state transportation agencies could adopt to respond or prepare for these impacts. For the highway system, information is presented on the climaterelated impacts on infrastructure, operations, and maintenance.
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Possible Impacts to the Highway System and the Natural Environment and Agency Responses to Them 43 A secondary impact of extreme and extended periods of heat, when combined with reduced precipitation, is the projected increased risk of wildfires and resulting smoke, especially in the west. Fire poses a risk to infrastructure and travelers, and can result in road closures.
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44 Strategic Issues Facing Transportation In Southern Canada, studies suggest that rutting and cracking of pavement will be exacerbated by climate change and that maintenance, rehabilitation, or reconstruction of roadways will be required earlier in the design life (Mills et al.
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Possible Impacts to the Highway System and the Natural Environment and Agency Responses to Them 45 Impacts on Operations/Maintenance Changes in rain, snowfall, seasonal flooding, and drought conditions can affect safety and maintenance operations on roads. More precipitation increases weather-related crashes, delays, and traffic disruptions and, consequently, loss of life and property.
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46 Strategic Issues Facing Transportation Impacts on Operations/Maintenance Generally, intense precipitation and increased runoff during winter months are likely to increase flood damage to tunnels, culverts, and coastal highways. The intense downpours can also lead to more landslides and affect roadway operations.
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Possible Impacts to the Highway System and the Natural Environment and Agency Responses to Them 47 sea levels and storm surges may also erode the road base and undermine bridge supports. The loss of coastal wetlands and barrier islands will lead to further coastal erosion due to the loss of natural protection from wave action.
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48 Strategic Issues Facing Transportation can act as a barrier, restricting the movement and migration of flora and fauna, fragmenting ecosystems, and changing the natural flow of water across the right-of-way. Roads can also be a local source of pollution and damage water bodies, as with the pollutants such as oil that run off roads with rainfall.
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Possible Impacts to the Highway System and the Natural Environment and Agency Responses to Them 49 • Roadside vegetation -- Current practices for maintaining or controlling roadside vegetation for a given region may not be well adapted to future climates. For instance, current roadside vegetation may not persist or may be more prone to fire under drier climate conditions.
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50 Strategic Issues Facing Transportation The impacts of climate change on the natural environment could necessitate a number of adjustments by highway planners, designers, and operators. Some of these changes will include the following: • Highway planners and designers will have to give more consideration to future changes and conditions before making decisions.
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Possible Impacts to the Highway System and the Natural Environment and Agency Responses to Them 51 Goal Actions Take operations, maintenance, and administrative actions now which enhance the response to and prevent impacts from extreme weather events Response Actions Enhance coordination with counties on detour routing and signal timing Install system that automatically adjusts signal timing to traffic conditions on key detour routes Provide GPS-capable devices to all snow plows Provide GPS-capable devices for maintenance crews and implement digital work orders Enhance cross-training in emergency maintenance tasks Install battery backups at all intersections that would require a traffic officer if there was an outage Implement an automated system for detecting stoplights affected by power outages Designate truck parking areas during snowstorms and convey information to truck drivers Install system that adjusts signal timing to road conditions on major arterials Expedite environmental permitting to allow drainage emergencies to be quickly addressed (general permitting) Incorporate more contingency clauses in construction contracts for extreme weather events Enhance real-time interaction between maintenance crews in the field and engineers prior to repairs Preposition equipment and conduct inspections before predicted extreme rainstorms Enhance coordination with utilities on at-risk infrastructure and emergency response Create a geographical information system (GIS)
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52 Strategic Issues Facing Transportation Goal Actions Develop a stronger understanding of the long-term implications of a changing climate on the state's highway network Identify sources of climate projections for key infrastructure design parameters through the year 2100 Designate official State Highway Administration/Maryland Transportation Authority climate projections (climate models, downscaling technique, and emissions scenarios to use) Identify the key climate threats to the transportation system through the year 2100 and their expected onset dates Identify critical thresholds where asset functionality and safety will be jeopardized and enter into asset management system Conduct high-level system-wide risk analysis of the climate threats to SHA assets; begin with one county pilot analysis Conduct detailed asset-specific vulnerability analyses for the most critical and unsafe high-risk assets Share risk analysis findings with the general public Develop denser network of stream gauges Integrate maintenance records and the asset management system Create a lessons-learned library for responding to climate change and extreme weather Clarify what perpetual responsibility for environmental mitigation measures means visà-vis climate change Develop long-term policy strategies for adapting existing infrastructure to climate changes as the need arises Create an internal climate change adaptation task force Develop a menu of possible adaptation solutions for common climate threats Identify funding sources for the standard adaptation solutions In consultation with the general public, set trigger thresholds for each asset that will initiate adaptation actions Using climate projections, forecast when the trigger thresholds are to be crossed for planning and budgeting purposes Develop and implement a monitoring system to determine when trigger thresholds are surpassed Enhance coordination on land use decisions that affect state roads Incorporate adaptation language in review of local comprehensive plans and site plans Link streamflow monitoring with stormwater management policies Consider adaptations in new projects to increase their resiliency to future climate impacts Incorporate climate adaptation needs into system planning and capital program development Incorporate climate change adaptation into the project development process Develop a transparent benefit–cost analysis methodology for comparing various adaptation options (including business as usual)
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Possible Impacts to the Highway System and the Natural Environment and Agency Responses to Them 53 • Agency office responsible for implementation, which includes whether in a lead or support role. (Note: Sixteen different agency offices were given some level of responsibility in implementing the policy)
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54 Strategic Issues Facing Transportation Climatic/ Weather Change Impact to Infrastructure Impact to Operations/Maintenance Precipitation Greater changes in precipitation levels If more precipitation falls as rain rather than snow in winter and spring, there will be an increased risk of landslides, slope failures, and floods from the runoff, causing road washouts and closures as well as the need for road repair and reconstruction. Increasing precipitation could lead to soil moisture levels becoming too high (structural integrity of roads, bridges, and tunnels could be compromised leading to accelerated deterioration)
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Possible Impacts to the Highway System and the Natural Environment and Agency Responses to Them 55 in the future and the risks to this infrastructure should be considered in today's decision making. This long-range perspective needs to be balanced with monitoring for near-term changes that may require more immediate adjustments.
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56 Although each step in the adaptation planning process is important from the perspective of conducting an adaptation study, one step in particular is critical to the overall success of the process -- the identification of the risk associated with system or facility disruption due to long-term changes in the climate or due to extreme weather events. Given that the legacy of facility location decisions can last far beyond the useful life of a project (that is, there is a good chance a facility will be rebuilt or expanded)
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Vulnerability Assessments and Risk Appraisals for Climate Adaptation 57 The risk equation shows that low-probability climate events (e.g., a Category 5 hurricane hitting the community) with high probabilities of asset failure and high consequence costs could still have high risk scores.
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58 Strategic Issues Facing Transportation in asset protection? Or is the agency going to fix the weather-related problems the highway network is currently facing on the assumption that such problems will only be exacerbated in the future?
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Vulnerability Assessments and Risk Appraisals for Climate Adaptation 59 Why Consider Climate-Related Risk? Risk assessments are performed to provide a platform for climate change adaptation decision making and planning to ensure the future resiliency of transportation infrastructure.
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60 Strategic Issues Facing Transportation Area's Metropolitan Transportation Commission in its "Adapting to Rising Tides" report (Metropolitan Transportation Commission et al.
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Vulnerability Assessments and Risk Appraisals for Climate Adaptation 61 failed asset? Part of answering this question is understanding how long the consequences might last, e.g., years, weeks, or hours or until capacity is regained through restoration, utilization of redundant assets, or changing mode of travel.
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62 Strategic Issues Facing Transportation Caltrans' Risk-Based Decision Making for Bridge Seismic Retrofit Caltrans' decision-making process on whether a bridge should be considered for retrofit is based on a multiattribute prioritization process. The screening steps are as follows: 1.
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Vulnerability Assessments and Risk Appraisals for Climate Adaptation 63 Caltrans' Risk-Based Decision Making for Bridge Seismic Retrofit (Continued) Summary of multiattribute decision procedure elements showing weighting percentages applied to each attribute.
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64 Strategic Issues Facing Transportation (Highways Agency and Parsons Brinckerhoff 2008)
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Vulnerability Assessments and Risk Appraisals for Climate Adaptation 65 – Attenuation and outfalls – Pavement maintenance – Flooding An adaptation work program was adopted that outlined specific tasks for each of the agency's units. Probability Ranges If an exact probability for an event occurring cannot be determined, this approach assigns probability ranges and links them to qualitative descriptors.
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66 Strategic Issues Facing Transportation The results of the tool application are shown in Table I.7 and Figure I.12. As shown in Figure I.2, Toronto has used the tool to determine the overall risk for the key assets that it is responsible for.
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Vulnerability Assessments and Risk Appraisals for Climate Adaptation 67 – Scientific studies: Some changes in climate stressors are more firmly grounded in scientific studies than others. For example, as noted in Chapter 3, predictions in changes in temperature have higher levels of confidence associated with them than changes in precipitation.
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68 Strategic Issues Facing Transportation • For asset failure – Expert opinion: Most transportation agencies have engineering staff or consultants who are very familiar with the design of different assets. Based on years of experience with asset failures (e.g., culvert failures given intense precipitation)
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Vulnerability Assessments and Risk Appraisals for Climate Adaptation 69 to higher emissions levels is built on a series of assumptions with wide potential variations, with each assumption having its own range of possibilities. The result of this reality is that there is a wide range of possible outcomes from climate models that could define the future.
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70 Strategic Issues Facing Transportation Each of these scenarios could be tested to derive climate variables and possible design responses. The dialogue resulting from this analysis should include the following: • What is the potential cumulative loss of functioning of damage over the lifetime of the asset (infrastructure damage, economic loss, etc.)
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71 The previous chapters have looked at adaptation efforts in the early stages of project development, that is, planning and problem definition. Once the need has been established for taking some action, either as a stand-alone adaptation measure or as part of another project, a more systematic project development process begins.
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72 Strategic Issues Facing Transportation date have consisted of a checklist of questions relating to the potential change in the affected environment. This guide suggests the following approach, which is similar but related to the diagnostic framework in Figure I.2.
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Climate Change and Project Development 73 Once these five questions are answered and documented, the more detailed engineering design can begin. The level of analysis that is used to answer these questions will depend on the requirements of federal or state law, the data and information that are already available (such as climate data for the state from an independent source)
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(continued on next page) Table I.8.
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Table I.8. (Continued)
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76 Strategic Issues Facing Transportation Table I.9 presents information for new infrastructure adaptation options. For example, Table I.9 indicates that for more extreme rainfall events and greater snowfall depths, increasing culvert size, using a small bridge instead of a culvert, or using a larger scour pool or rip rap could be considered.
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Table I.9. Adaptation options for new culverts.
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78 Strategic Issues Facing Transportation Table I.10. Adaptation options for existing culverts.
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Climate Change and Project Development 79 Step 2: Identify the Possible Climate-Affected Design Parameters for the Given Asset Type Step 2 of the analysis identifies the specific climate stressors to which the project will likely be subject. The detailed tables in the spreadsheet and the decision support tool on the accompanying CD-ROM can assist in this effort.
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80 Strategic Issues Facing Transportation When a second-order climate variable exists, engineers have often developed various approaches to model that variable. These are listed in Column E of the table, Method for Estimating the Second-Order Climate Variable, and under the heading Climate Influenced Design Inputs on the relevant engineering information page of the tool (see Figure I.14)
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Climate Change and Project Development 81 parameters from the sources traditionally consulted by engineers. These sources are listed in the tables under Column G, Typical Source(s)
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82 Strategic Issues Facing Transportation parameters affects the design is critical to determining what adaptive actions can be taken in later steps. In the tables, each parameter's impacts on design are shown in the Affected Design Components column (Column I)
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Climate Change and Project Development 83 component. Retrofitting involves making a physical adjustment to an existing design to accommodate projected changes in the design parameters.
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84 Strategic Issues Facing Transportation low ($ in the tool) corresponds to a 1 to 5 percent addition in total asset cost, moderate ($$)
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Climate Change and Project Development 85 alternatives to determine (1) whether taking adaptive action is prudent and, if so, (2)
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86 Chapter 2 examined the possible linkages between adaptation assessment and transporta tion planning, and Chapter 6 described how adaptation could be incorporated into the envi ronmental analysis and engineering activities of project development. This chapter examines the relationship between adaptation concerns and core agency activities with emphasis on construction, operations and maintenance, and asset management.
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Other Agency Functions and Activities 87 over project duration. These standard adjustments are typically included in bid documents.
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88 Strategic Issues Facing Transportation control alone costs state DOTs about $2.5 billion annually -- almost 40 percent of road operat ing costs. With the population in coastal areas vulnerable to extreme weather events expected to more than double over the next 20 years, operations strategies that will allow emergency evacuations and emergency response efforts will become even more critical.
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Other Agency Functions and Activities 89 Lockwood (2008) suggests that changing climatic and weather conditions lead to several operations actions that transportation agencies should consider: • "Improvements in surveillance and monitoring must exploit a range of potential weather sensing resources -- field, mobile, and remote." • "With improved weather information, the more sophisticated archival data and integration of macro and micro trends will enable regional agencies to improve prediction and prepare for longterm trends." • "This in turn can support the development of effective decision support technology with analyses and related research on needed treatment and control approaches." • "The objective to be pursued would be road operational regimes for special extreme weatherrelated strategies such as evacuation, detour, closings, or limitations based on preprogrammed routines, updated with real-time information on micro weather and traffic conditions." • "For such strategies to be fully effective improved information dissemination will be essential -- both among agencies and with the public, using a variety of media." • "Finally, the institutionalization of the ability to conduct such advanced operations will depend on important changes in transportation organization and staff capacity as well as new, more integrated interagency relationships." With respect to maintenance as commonly practiced, an agency's maintenance forces "own" the highway system, and as illustrated in Chapter 4, "their" system and "their" activities are • Monitor and clean, as needed, bike lanes, shoulders, and non-motorized trails in vertical curve sag areas • Ensure all roadside building designs are LEED certified or modified to be energy efficient • Encourage more night/cooler weather work to prevent damage such as slab curling, premature cracking, loss of air entrainment in concrete pavements, rutting, and flushing in asphalt pavements • More closely monitor moisture in aggregate piles • Incorporate materials whose performances are less variable in weather extremes • Modify vegetation planting periods to ensure optimal growth and survival • Stronger specifications for dust control and wind erosion • Stronger strategies for worker safety during extreme heat periods Hotter Drier Summers • Design lower maintenance bridge expansion • Design seed/vegetation mixtures that create a denser, deep-rooted vegetation mat that is more erosion resistant • Eliminate monoculture roadside vegetation designs that may not survive extended drought periods or invasive species attack • Make sure vegetation is managed appropriately during drought periods near roadsides that are susceptible to wildfires • Monitor and be ready to respond quickly to pavement "tenting" due to excessive heat • Monitor health of vegetation in right-of-way that may be stressed due to extreme weather or invasive/new northerly migrating insect species and remove/replace, as necessary Source: Johnson (2012)
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90 Strategic Issues Facing Transportation likely to be subject to different climatic conditions and extreme weather events. In approaching this topic it is important to keep in mind that as the longterm stewards of the highway system, maintenance forces perform thousands of operations large and small every day to preserve and operate the highway network in a safe and efficient manner.
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Other Agency Functions and Activities 91 The remedy is to provide additional resources for culvert management, repair, and retrofit; how ever, this is often beyond the capacity of an overcommitted maintenance budget. The coopera tion and communication necessary to obtain general permits for culvert work from regulatory agencies is also sometimes lacking.
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92 Strategic Issues Facing Transportation Several of these components could have relevance to climate change–related factors that affect the condition (current or future) of highway assets, e.g., the objectives and measures for asset management, lifecycle cost and risk management, and investment strategies (Aktan and Moon 2009, AbouRizk and Siu 2011)
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Other Agency Functions and Activities 93 could be included in asset performance modeling and assessment that will "flag" those assets that might represent high risk to the agency and to the transportation system. Over time, with advancements in the technologies of monitoring infrastructure health, "smart" sensors may be able to be tied into the periodic monitoring of infrastructure assets with the output linked directly to the asset management system database.
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94 Strategic Issues Facing Transportation For example, within any one geographic area, the street and highway network as well as intermodal connections may be under the jurisdiction of a half dozen or more agencies. It is not difficult to envision adaptation strategies that might be inconsistent or even conflicting.
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Other Agency Functions and Activities 95 • Developing effective strategies to respond to or implement programs required by legisla tion that have as their focus multimodal, multijurisdictional, and/or multidisciplinary solutions The handbook identifies different organizational actions and methods for enhancing collabo ration including purpose and needs statements, agreement on language and terms, ad hoc plan ning and decision structures, task forces/committees, common work/activities program, staff assignment/rotation, staff training, thirdparty facilitation, memorandum of understanding/ agreement, collaboration technology, colocation of staff, and formation of a new organization. It is not likely that all of these strategies would be relevant for a collaborative adaptation program; however, they do represent a range of strategies that can be used to foster multijurisdictional and multiagency cooperation.
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96 Aktan, A
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References 97 Commonwealth Scientific and Industrial Research Organization (CSIRO) , Maunsell Pty Ltd, and Phillips Fox.
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98 Strategic Issues Facing Transportation Kirshen, P., S Merrill, P
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References 99 National Research Council.
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100 Strategic Issues Facing Transportation U.S. Environmental Protection Agency (U.S.
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101 A P P E N D I X A Sea-Level Rise Projections Note: Eustatic sea level rise by 2050 is 1.65 inches for B1, 4.72 inches for A1B, and 9.17 inches for A1FI. Sea-Level Rise by 2050 Relative to 2010 (in inches taking into account subsidence and uplift)
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102 Strategic Issues Facing Transportation Sea-Level Rise by 2100 Relative to 2010 (in inches taking into account subsidence and uplift)
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103 A benefit–cost (B/C) methodology was formulated to provide results for a "point of decision" analysis -- in other words, an exercise to determine whether an adaptation strategy or project is worth the additional expense.
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104 Strategic Issues Facing Transportation Figure I.B-1. Climate-risk-adjusted benefit–cost methodology.
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Benefit–Cost Methodology for Climate Adaptation Strategies 105 with major rehabilitation or reconstruction work are addressed in Step 3. The Economic Analysis Primer also recommends estimating all future costs in constant year dollars, without applying an inflation factor.
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106 Strategic Issues Facing Transportation decreased productivity for local businesses and decreased business attraction for the region. For another perspective on understanding the potential economic impacts of asset failure, refer to Georgia Tech Research Corporation (2012)
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Benefit–Cost Methodology for Climate Adaptation Strategies 107 units of increase, such as "2 feet of surge." For first-order stressor types, such as precipitation, the extent to which they contribute to second-order impacts, like flooding, should be considered (e.g., a major culvert is designed for the 1 percent chance flood event, the flow rate of which becomes the critical threshold)
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108 Strategic Issues Facing Transportation would have the same probability of failure for the adaptation scenario in subsequent years. For example, if water levels overtake a bridge that has not been adapted, it is assumed that the new bridge will be built to withstand higher water levels.
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Benefit–Cost Methodology for Climate Adaptation Strategies 109 where ACAi = agency costs of adaptation scenario in year i OMA = annual operations and maintenance costs of the adaptation scenario (from Step 2) PFAi = probability of asset failure in year i for the adaptation scenario (from Eq.
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110 Strategic Issues Facing Transportation Di = discount factor for year i [for guidance on estimating a discount rate, refer to FHWA (2012)
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Benefit–Cost Methodology for Climate Adaptation Strategies 111 first. Incremental calculations are recommended.
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112 Strategic Issues Facing Transportation Based on these assumptions, the annual user costs of failure ranged from $130 million in 2011 to $234 million in 2050 (these values are in constant year dollars)
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Benefit–Cost Methodology for Climate Adaptation Strategies 113 As with traditional B/C approaches, climate-risk–adjusted analyses can provide key inputs into several different transportation decision-making processes, including: • Long-range planning: With minor modifications, the B/C methodology can be employed to help agencies identify the appropriate time frames in which implementation of adaptation strategies is cost effective (this is the "planning" application type)
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