TRANSPORT KNOWLEDGE NOTE Supporting Road Network Vulnerability Assessments in Pacific Island Countries In Pacific Island Countries, high vulnerability to the impacts of climate change and natural disasters means that such events can have devastating social and economic impacts when critical infrastructure is compromised.1 This has been apparent in countries where severe disruptions to road networks have resulted in a loss of access to basic infrastructure and services. Building resilience is therefore a prerequisite for long-term sustainable development, and Governments will increasingly seek tools that can help guide investment and policy decisions by considering the effects of climate change and natural disasters. Among such tools are road network vulnerability assessments, which provide a means to design and maintain a climate resilient network. This article highlights the process and lessons learned from the Vulnerability Assessment and Climate Resilient Road Strategy of the Samoan road network, and outlines a replicable approach for small island nations with acute capacity challenges that seek to balance analytical rigor with the need for practicality. Transportation Networks in Pacific by the road network. While inter-island transportation may be conducted via Island Countries seaports and airports, the accessibility of the maritime and aviation transport still needs to In most countries, the transportation of people be guaranteed by intra-island road networks. and goods is essentially completely facilitated However, in some parts of the world, and 1 In acknowledging that a variety of definitions may be used for the terms risk, hazard, vulnerability and exposure, the following definitions are used for this article. Risk refers to the likelihood that a bad outcome occurs to an exposed asset (e.g., bridge failure) within a specified period because of the effects of natural effects (e.g., tropical cyclone induced storm surge). Hazard refers to when the effects of the natural events reach or exceed specified levels at a certain location within a period (e.g., storm surge exceeding 1 meter). Vulnerability refers to the propensity of an asset to be damaged by the effects of an event. Exposure refers to when assets are in harm’s way. PHOTO CREDIT: WEST COAST ROAD, SAMOA. CONOR ASHLEIGH, WORLD BANK especially in Pacific Island Counties (PICs), the climate change, and where the frequency risk posed to transportation networks by and/or intensity of climate and extreme geophysical and climate-related events such weather events are projected to increase, so as earthquakes and tropical cyclones is too will the impacts on coastal roads and relatively high and the impact can be severe. other assets. Therefore, the challenge faced Such events can cause severe damage to by many PICs is how to best enable the road infrastructure, particularly the transport sector to adapt the impacts of climate network, and result in significant adverse change and how to strategically plan for the effects on livelihoods and the loss of lives. impacts of climate change, accounting for future vulnerability issues, to better inform PICs have many common obstacles to adaptation and resilience building efforts and building resilience for critical infrastructure. For ensure the sustainability of investments and example, land area is limited and development efforts. Mainstreaming climate infrastructure such as hospitals, schools, adaptation into transport sector planning is places of employment, tourist infrastructure, therefore critical to ensuring that appropriate port facilities, power plants, and often airports, management solutions are provided to are located primarily within the coastal zone. reduce climate risks for road sector assets and The road networks are often not complex and to build lasting climate resilience. have very few redundant paths; therefore, damage to a single road link or a bridge may Since road networks are geographically completely interrupt communities access to distributed, varied in nature and are subject to crucial lifelines, such as airports or hospitals. In a variety of hazards, many interventions could addition, most of the population also lives be possible to mitigate the risk of network near the shoreline, and are largely served by failure; however, the selection process for the coastal roads, meaning the reliability of these best strategy forward might not be coastal road networks are critical in ensuring immediately obvious to decision makers. connectivity. Island ring roads are crucial for Because budgets are often constrained, guaranteeing the daily movement of people prioritization of interventions is needed that and goods, however some sections of these considers social and economic factors. An roads are situated steps from the coast. The objective, defensible, transparent and road networks, other infrastructure, and the repeatable approach to prioritizing all communities that live along them are faced feasible alternative risk mitigation options is with a range of specific and severe therefore necessary. Road network vulnerability issues including: (i) exposure to vulnerability assessments provide a means to sea-level rise, wave action during very high achieving a comprehensive approach to tides, storm surges, cyclones and tsunamis; (ii) effectively managing risks by (i) identifying the flash flooding and landslides during extreme threats posed by geophysical and climate- rainfall events; (iii) damage from earthquake related events (ii) assessing the risk of transport ground motion; and, (iv) accelerated network failures (iii) assessing potential infrastructure deterioration due to extreme damage to network components (e.g., weather, aggressive salty environment and bridge and road links) and potential impacts rising water tables. In addition, there is often to communities and economies; (iv) limited capacity and resources compounded identifying potential measures to enhance with many competing priorities, which limit the the resilience of transport networks; and, (v) ability to undertake country (network) scale undertaking a cost-benefit analysis of assessments to address such challenges. potential measures to inform the prioritization of investments. This can help decision makers Furthermore, the vulnerability of the transport answer the question as to how one can network in PICs is expected to increase due to establish and deliver a fit-for-purpose resilient TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 2 road network. lives within one km of the coast, with key infrastructure located predominantly within the coastal zone. The islands of Upolu and Savai’i suffer regular breaks of serviceability THE SAMOAN ROAD NETWORK due to vulnerable links or locations becoming impassable from flooding, debris deposit, VULNERABILITY ASSESSMENT and/or culvert, bridge and pavement damage. Expected climate change effects In Samoa, a Vulnerability Assessment of the will further put these coastal assets and road network in Upolu and Savai’i (1150 communities at a higher level of risk kilometers) was undertaken to support the (Government of Samoa, 2017b). Constraints development of a Climate Resilient Road on financial and technical resources limit the Strategy to provide a comprehensive capacity to effectively plan for, and assessment of and sector planning strategy proactively enhance resilience to climate for the national road network. This included change. identifying key hazards, assets and areas vulnerable to severe weather events, The Pilot Program for Climate Resilience assessing the impacts of climate change, as (PPCR) of the Strategic Climate Fund (SCF) well as analyzing current practices in network employs a programmatic approach to help development, maintenance and asset countries around the world integrate climate management to outline strategies, and resilience into development planning across support the development of maintenance sectors and stakeholder groups. With the plans that, if implemented, would decrease challenges faced by Samoa in mind, as part the vulnerability of the road network. The work of the PPCR, Samoa undertook a Vulnerability undertaken in Samoa is examined here to Assessment and Climate Resilient Road propose an approach that is appropriate and Strategy under the Enhancing the Climate replicable in other PICs. Resilience of the West Coast Road (CRWCR) Project. The CRWCR Project aims to: (i) improve the climate resilience of the West COUNTRY CONTEXT Coast Road (the main road connecting the international airport to the capital Apia); and, Samoa is a small island developing state (ii) enhance local capacity to develop a located in the Pacific Ocean and is highly more climate resilient road network. As part of vulnerable to the impacts of geophysical and achieving the second objective, the climate related events. Past extreme events Vulnerability Assessment and Climate Resilient have caused severe damage to the Road Strategy identified and prioritized infrastructure (particularly the transport locations that require investments to improve network), severely impacted livelihoods, and the resilience of the national road network resulted in the loss of lives. For example, based on assessing asset exposure and Tropical Cyclone Evan, which struck Samoa in resilience, undertaking cost-benefit analyses 2012, resulted in total estimated damage and and incorporating social analyses. loss equivalent to about 28 percent of the total value of goods and services produced in Following the completion of the Vulnerability Samoa in 2011 (Government of Samoa, 2013). Assessment and Climate Resilient Road Strategy, these reports have been used by the The road network is of critical importance to Government of Samoa to further guide the development of the country by providing investment plans within the road sector and to access to economic activities and social optimize the allocation of available resources. services. However, vulnerability is high as In addition, the priorities identified through the approximately 70 percent of the population TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 3 assessments have been utilized in the direction of future changes when using global preparation of a new climate resilient climate models, and it is not possible to transport project. predict changes in greenhouse gas emissions in the future decades. Due to the many TASK OVERVIEW variables involved in making projections, such as the choice of climate model and the As part of the Samoa Vulnerability timeframe of projection, Samoa’s Assessment, the following tasks were Vulnerability Assessment included a undertaken to assess the risk of transportation straightforward sensitivity analysis to assess network failures by identifying geographical how different projections may produce areas at high risk of exposure to natural different impact results and different hazards and assets vulnerable to future approaches to improving the resilience of the climate change impacts. network. An assessment of the climate model used, Representative Concentration Task 1 – Rainfall and climate change Pathways , future year and Annual Return 4 projections: Interval5 were examined as part of the assessment process. This task involved the production of precipitation Intensity-Duration-Frequency Task 2 – Vulnerability Analysis of Road (IDF) curves2 to help form the basic starting Network: point for any future drainage designs in Samoa. A milestone for the Vulnerability This task involved: Assessment was the application of updated I. Performing geo-referenced mapping of hydrological data for Samoa as the basis for the critical road links, bridges and any making rainfall projections. Historical daily other damageable asset. The emphasis rainfall data for two stations – Apia and on damageable assets here is important Faleolo – covering 30 years (1984 – 2014), because the risk assessment of a road monthly data from the 1980’s for four stations network can be simplified at times by on Savai’i and one on Upolu, and 10-minute identifying items that, using expert data from 2010-2015 for two stations – judgment, are much less damageable Nafanua and Afiamalu – were obtained. In than all the others. For example, stretches addition, the reported long-term increase in of road located inland at locations not relative sea level at Apia (3.7 millimeters per subject to landslides or flooding may be year since 1993) was used as an indication of identified as less exposed to simplify the sea-level rise (Australian Bureau of risk assessment study. If warranted, this Meteorology). In addition, rainfall and simplification can help to make this task temperature parameters were modeled as more manageable, and the part of the climate change scenarios using consequences of such a simplification on the Delta Method3. the robustness of the assessment, is usually negligible. In Samoa, surveys were In addressing climate change risks, the ability undertaken of the road network using a to address uncertainty is often questioned. Blackvue dashcam, to give a video There can be disagreement on the scale and recording, GPS coordinates and an estimation of road roughness from 2 A graphical representation of the probability that a given 4 Four greenhouse gas concentration trajectories adopted average rainfall intensity will occur. by the Intergovernmental Panel on Climate Change. 3 A statistical downscaling approach using historical large- 5 The average or expected value of the periods between scale atmospheric and local climate characteristics and exceedances of a given rainfall total accumulated over a global climate models to project future local climate given duration. characteristics. TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 4 acceleration data. The results of the surveys were used to identify the This task involves: damageable assets (e.g., road links and I. Deciding the types of natural events bridges susceptible to damage from that the risk assessment study intends to tropical cyclones). consider and selecting the effects of the II. Assessing the unit replacement cost of natural events that one intends to any such item (for road links, it could be consider in the risk assessment of the cost per kilometer, while for bridges it assets at hand. For road networks in PICs could be the replacement cost of the an obvious choice would be tropical entire bridge). cyclones (with associated storm surge III. Categorizing any damageable asset risk) and earthquakes (with associated belonging to the road network into ground shaking and earthquake- vulnerability classes, namely groups of induced tsunami risks). Note that the assets that have similar vulnerability to the type of assets exposed drives this effects of the natural events to which they selection. Three main groups of hazard are exposed. For simplicity, if we assume were identified in Upolu and Savai’i: (i) that the network is comprised only of storm surge and coastal inundation; (ii) roads and bridges, existing roads could landslides; and, (iii) river and tributary be placed into four classes, primary and flooding. The probability of occurrence secondary roads and those in “good” or were then classified as high, medium in “bad” condition; and existing bridges and low. Coastal hazards for example can be categorized into types defined in were delineated based on proximity of terms of construction material (e.g., the road to the coastline: High (<5 reinforced concrete or steel), span meters); Medium (5-50 meters); and, length, and year built brackets (e.g., Low (>50 meters). Hazard indicators before 1970, between 1970 and 2000, were chosen associated with road and after 2000). damage and loss of accessibility and connectivity. The approach to The output of the exposure component is an addressing vulnerability (the degree of ‘asset register’ i.e., a geo-referenced exposure and resilience) in Samoa was database containing all the damageable time-bound to prioritize actions, with components of the network (e.g., road links high vulnerability addressed in the short- and bridges) divided into appropriate term, medium vulnerability in the vulnerability classes, their replacement cost medium-term and low vulnerability in and, in the case of networks, the connectivity the long-term. of all the components within the network. The II. Estimating the likelihood of occurrence existing asset register in Samoa is the Samoa of the natural events of different Asset Management System (SAMS) a “strength” (for strength we mean the computerized system developed to help potential for the hazard to generate strengthen institutional capacity to different levels of impact) that may pose proactively manage assets, which is a threat to the road network. This task, managed by the Land Transport Authority which is empirically based, requires a (LTA). Outputs from the Vulnerability statistical analysis of the historical Assessment (e.g. results from the Blackvue catalogues of events in the region and recordings) are being used to strengthen any modern technology that can SAMS. provide useful information. This task is very time consuming and may require Task 3 – Natural Hazard and Climate Change multi-disciplinary expertise including that Risk Assessment: of meteorologists, climatologists, TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 5 seismologists, geologists, geophysicists and engineers. In the case of earthquakes, this task assumes that in historical and recent pre-historical times the occurrence of earthquakes can be considered a stationary process. Therefore, the rates and the characteristics of earthquakes that will occur in the future can be estimated from the rates and the characteristics of earthquakes that have occurred in the past. For the case of tropical cyclones, however, this task is made more complex by the effects of climate change as the occurrence and characteristics of future cyclonic events may not be the same as those that occurred in the past. III. Predicting the severity of the effects of any natural event of given characteristics. This task entails, for example, the ability to estimate the amount of storm surge inundation caused by a tropical cyclone, and requires the specific modeling skills of oceanographers, meteorologists, and earth scientists. The use of scenario analysis here in subtasks I and II provide a means to help strategically manage assets and planned investments by anticipating trends and developing alternative pathways, thereby moving assessments towards being more forward looking. Scenario analyses have emerged as an important tool to help inform strategic decision-making processes in the face of uncertainty. Storm surge inundation modeling was undertaken to determine the impacts of tropical cyclones on the road network in Upolu and Savai’i, and is provided in further detail below. TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 6 A Robust and Implementable Approach to Hazard Assessments: Storm Surge and Inundation Modeling Increases in heavy rainfall, strong winds, storm surges, and high sea levels are predicted for Samoa (Pacific-Australia Climate Change Science and Adaptation Planning Program, 2014), which will have detrimental consequences for the Samoan Road Network and transport sector assets. Hazard assessments can be complex, expensive and onerous, and are often not feasible for PICs. To assess the risks to Samoa’s road network, a practicable approach was undertaken at an appropriate scale based on data that was available and accessible. To assess the impacts of tropical cyclones on the road network and to assess the impact of loss of connectivity and access in priority areas, storm surge modeling was undertaken using the experience of recent severe weather events including Tropical Cyclone Evan (2012), Val (1991) and Evan (1997). Five study sites across Upolu and Savai’i were chosen for the simulation of coastal inundation (Figure 1). Figure 1. Inundation map showing maximum surface elevation on Upolu (East), following cyclone Evan. The red line indicates the main coastal route (Source: Government of Samoa, 2017b). The analysis included three main undertakings: 1. Data collation and review: relevant data and previous reports were collated and reviewed to provide a full understanding of the issues. In addition, bathymetric and topographic data was gathered from a remote sensing method known as Light Detection and Ranging (LiDAR) and was incorporated into the analysis as well as the production of a digital elevation model. 2. Cyclone wind analysis: significant historical tropical cyclone events were selected. 3. Numerical modeling: MIKE 21 Flexible Mesh modeling suite was used to set up a regional scale coupled hydrodynamic and spectral waves model covering Upolu and Savai’i and encompassing the approach path for the selected cyclones. The output of the analysis was a calibrated hydrodynamic model coupled with a spectral wave model for wind waves. The impact of storm surge on the road network was assessed and the roads with the highest inundation depths were identified as most vulnerable to help prioritize sites selected in the Climate Resilient Road Strategy. TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 7 Task 4 – Assessment of Vulnerability: employment, health and disability; (ii) relevant quantifiable infrastructure and I. Vulnerability assessments require the facilities such as availability and ability to estimate the level of damage, accessibility of escape paths, sirens, and therefore downtime and monetary wheelchairs for persons with disabilities; loss that would be required for fixing the and, (iii) qualifiable indicators such as damage suffered by any asset in the the existence of a community disaster vulnerability classes identified (e.g., a management plan (community primary road link in good condition) preparedness), reliance on the road to when it experiences any given level of access emergency services and/or intensity of the effects under escape (distance to nearest hospital consideration (e.g., an inundation of 2 and safe house), and knowledge of meter of storm surge water for 24 hours). climate change. II. Considering the damage estimated for IV. A cost-benefit analysis assessment was all the damageable components of the undertaken to inform an investment network, for any given earthquake or plan. The economic indicators – tropical cyclone, the model needs to beneficiaries, costs, internal rate of estimate the level of damage of the return and net present value (NPV) – entire network measured in terms of the were used to assess the comparative selected metric (e.g., network service performance of a variety of alternative disruption and losses). For example, if the options for investment. Depending on model predicts that after a storm several the risk-aversion of decision makers, road links have minor damage but are several criteria can be used to choose passable, some links have severe the best alternative. Very risk-averse damage and are not passable, and a decision makers can choose the bridge has collapsed, what is the alternative that minimizes the maximum downtime of the entire network before regret over all scenarios considered. In the damaged items are temporarily other words, this is the alternative whose fixed and the traffic can resume? What expected NPV of the losses (direct plus are the direct repair losses and the indirect costs) over the chosen period is indirect losses to the stakeholders due to minimum under the worst-case the road network damage? scenario. Other decision-makers might III. A large focus in assessing network choose the alternative whose expected vulnerability has been on technical NPV of the losses (direct plus indirect adaptation and the economic costs of costs) over the chosen period is associated with ensuring the ability of a minimum in as many scenarios as road network to maintain its level or possible. Others might choose the performance following an event, and alternative whose expected NPV of the therefore often solely limited to losses (direct plus indirect costs) over the indicators of reliability. As part of the chosen period is minimum on average Samoa Vulnerability Assessment, over all scenarios. In any case, the aspects of social vulnerability were decision makers will need to keep in investigated and linked to the mind the possible consequences of their engineering and economic analysis to choices in the worst-case scenario, and provide a more holistic approach to be ready to react in case it materializes. assessing the costs for adapting to climate change. Three indicators were The output of this task consists of multiple sets used including: (i) quantifiable social of so-called damage functions and downtime indicators such as age, income, gender, functions for all asset classes. Damage and TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 8 downtime functions are probabilistic addition would have been a valuable relationships that provide expected level of addition to bring further confidence to the losses (e.g., 10 percent, 20 percent, etc.) or of analytical underpinnings of the risk piece, the repair time (and their uncertainty) for any feasibility of this approach in low capacity given level of intensity of the effects of an environments where data challenges (both in event (i.e., tsunami wave heights caused by terms of availability and accessibility) are a earthquakes). Damage functions are used to binding constraint requires deliberation. To estimate the direct ground up losses (as a address this challenge in Samoa, the fraction of the replacement cost of the asset) consultants’ approach to the storm surge suffered by any component in each inundation modeling by assessing the impact vulnerability class present in the network, while of three relatively recent cyclones across downtime functions are used to estimate the priority sites provided a practical and time needed to fix the damage and make the replicable approach valued by the client. In asset operable again. The total direct losses comparison, Annex 1 provides a framework caused by an event are simply the sum of the for catastrophe risk assessments that could be losses suffered by each component. The utilized in countries with higher capacity and computation of network downtime is, where greater resources are available. however, less immediate and it is specific to each network. For any pattern of damage to CLIMATE RESILIENT ROAD STRATEGY the components of the network and related downtime, the length of the service disruption Samoa’s Vulnerability Assessment was used to of the network (if any) can be estimated with inform its Climate Resilient Road Strategy, only that knowledge and the knowledge of which guides the time-bound strategic the connectivity of each component. considerations (short, medium and long-term) to be addressed by the Government and its Task 5 - Probabilistic Risk Assessment: line ministries. For example, coastal inundation measures can be implemented in the short to The inclusion of catastrophe risk assessments, medium-term through raising the elevation which incorporate probabilistic risk analysis, and coastal protection works, while a long- provides one option to improving the term solution may be an alternative inland vulnerability assessment methodology. Since route. Thus, a road strategy report may outline there are many sources of uncertainty when it a general climate change adaptation policy comes to predicting the impacts of framework and objectives, recommend a catastrophes, the additional inclusion of program of priority investments and other probabilistic methods can help the decision- interventions at specific risk locations, and making process in the face of uncertainty. The propose specific policy reforms required to output of catastrophe risk assessments is a provide a foundation for climate change stochastic6 catalogue of simulated future adaptation and to address natural hazard events to each component of the road vulnerability in the sector. As previously noted, network. The benefit of this method is that it to address the vulnerabilities identified, high combines multiple modeling views of vulnerabilities may be addressed within the exposure, hazard and vulnerability to obtain short-term, medium in the medium-term and various alternative views of risk, providing the low in the long-term. Examples of the short, most comprehensive set of information for the medium and longer-term priority investments decision-making process. The Samoa identified in Samoa include: retrofitting and Vulnerability Assessment did not include a rehabilitation of existing infrastructure, catastrophe risk assessment, and though the securing alternative inland routes, improved 6 Randomly determined or having a random probability distribution. TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 9 maintenance regimes (routine, preventative, standards, and maintenance remedial), and capacity development procedures considering expected (Government of Samoa, 2017a). climate change; o Develop and strengthen tools to assess It is important to note here that documents the vulnerability of road assets to should link to the existing institutional and climate change events, including the policy framework to further embed climate methodologies for determining the change considerations into road adequacy of existing roads to resist infrastructure development and to help climate change impacts; and, speed up the process at which actions can o Review the institutional and legal be undertaken. As such, Samoa undertook a framework and recommendations for review of existing plans and strategies to specific reforms required to facilitate ensure that any recommendations from the climate change resilience within the outputs also aligned with national and road sector from infrastructure and regional aspirations. The Vulnerability operational perspectives. Assessment and Climate Resilient Road Strategy have therefore been framed within This engagement has provided Samoa with an the existing institutional context. investment and maintenance strategy to enhance the climate resilience of the road Lastly, an area within the network that is network as well as new methodologies, considered less vulnerable today will have a techniques and software and the institutional different vulnerability in the future should its capacity to more effectively plan and infrastructure or population change. manage the road network. Samoa’s Cabinet Therefore, systems planning needs to be Development Committee approved the treated as a dynamic process, which means Vulnerability Assessment and Climate tools such as Samoa’s Vulnerability Resilient Road Strategy in August 2017, Assessment and Climate Resilient Road recognising the importance of the reports for Strategy need to be updated regularly to inclusion within the existing institutional provide policymakers with the best available framework and setting a milestone of information so they can continue to make transformative change in the way that climate informed investment and policy decisions. change is addressed in Samoa’s transport sector. OUTCOMES LESSONS LEARNED The approach undertaken in Samoa through its Vulnerability Assessment helped to: Through the work undertaken in Samoa, practical operational lessons were identified o Provide a general climate change that should be considered when trying to adaptation policy framework and undertake a similar exercise in other small objectives for the national road island nations: network; o Identify and prioritize specific locations Management. The management of such a that require investments to improve complicated assignment can be a challenge, the resilience of the road network particularly when it comes to reviewing including short (1-5 years), medium (5- deliverables. It is sensible to undertake 10 years) and long-term (10+ years) capacity building during preparation and resilient investments; implementation of the vulnerability o Provide an outline of specific measures assessment to ensure Governments can to update design and planning effectively oversee these multi-disciplinary TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 10 teams and then implement the assess the qualifications of such teams, the recommendations derived from their work. procurement evaluation committee must have the ability to assess the proposed team’s Maintenance. There is a general lack of skills and methods to ensure technical regular maintenance in many PICs and this is proposals are not over-weighted in any one a pressing issue that needs to be prioritized. area (e.g. engineering, disaster risk analysis, This entails not just regular routine climate science), but adequately balance all maintenance such as clearing drains, but also aspects for optimal assessment. Samoa preventative maintenance such as followed best practice by recruiting a conducting slope stabilization to prevent technical advisor to develop a methodology landslides, which can cause damage to road and train the panel to adequately assess the links and then require road clean-up (routine various technical proposals. maintenance). Feasibility. It is however important to keep in Data Availability. Robust vulnerability mind that the assessment undertaken is assessments often require copious amounts of feasible in terms of consistency with monetary data for rigorous analysis. However, in small and non-monetary constraints. For example, island countries such as Samoa, good quality moving a coastal road from the coast to a datasets are generally unavailable, often mountainous area two kilometers inland may because the country has not had the be outside the available budget. resources to record the data. In other cases, Alternatively, building a sea wall along a long the datasets may be available, but not stretch of coastal road to reduce the accessible as the distribution from the owners likelihood of coastal inundation and storm and custodian to the project team dealing surge impacts may be economically viable with risk assessment is not always smooth. To but may only be a short-term solution and overcome the accessibility issue, it is may have negative environmental impacts or important that the relevant stakeholders are may not be acceptable to communities in the well informed about the work and buy into the area. The cost and the mitigated risk of value it will deliver to all of Government and feasible alternatives (e.g., road networks with ultimately the people. Thus, it important to different proposed variants) therefore need to engage coordinating Ministries (i.e. the be evaluated. In addition, the inclusion of Ministry of Finance in most PICs) early in the complex modeling and risk assessments need activity, as they play a pivotal role in ensuring to be appropriate for the context. It is also vital effective communication across relevant line that the Government targets an acceptable Ministries and securing their participation level of reliability of road networks and, during the data-gathering process. At the end therefore, limits the likelihood of service of the assignment, all data assembled should disruption to levels that are compatible with be catalogued and provided to Government realistic expectations of the stakeholders. as well as stored in an open data repository for future access. WAY FORWARD Procurement. National road network The pilot approach undertaken in Samoa is a Vulnerability Assessments need to be valuable addition to transport sector planning conducted by multi-disciplinary teams with and provides a replicable option for other skills and experience in several areas (e.g. PICs that can be tailored to country needs engineering, disaster risk management, and lessons learned. Building on lessons climate change analysis, economics, learned from the Samoa Vulnerability hydrology, GIS mapping, environmental and Assessment, a key discussion for PICs wanting social assessment, policy review). To properly to conduct similar national road network TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 11 assessments is to determine the level of sophistication desired, considering the trade- offs between the additional benefits of including a probabilistic risk assessment and the time, resources and capacity available. CONTRIBUTORS This note was prepared by a team including Sean David Michaels, Paolo Bazzurro and Keelye Hanmer. The team benefited from valuable guidance from peer reviewers Vincent Vesin, Frederico Ferreira Fonse Pedroso, and Maria Cordeiro. Denis Jean-Jacque Jordy, Julie Rozenberg and Christopher Bennett all provided useful comments. TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 12 RESOURCES Australian Bureau of Meteorology, The National Tidal Centre. http://www.bom.gov.au/oceanography/projects/ntc/ntc.shtml Government of Samoa, 2013. Samoa Post Disaster Needs Assessment Cyclone Evan 2012. https://openknowledge.worldbank.org/bitstream/handle/10986/15977/ACS44320ESW0wh00Box 0379812B00OUO090.pdf?sequence=1&isAllowed=y Government of Samoa, 2017a. Climate Resilient Road Strategy. Government of Samoa, 2017b. Vulnerability Assessment of the Samoa Road Network. Pacific-Australia Climate Change Science and Adaptation Planning Program, 2014. Climate Variability, Extremes and Change in the Western Tropical Pacific: New Science and Updated Country Reports. https://www.pacificclimatechangescience.org/wp- content/uploads/2014/07/PACCSAP_CountryReports2014_WEB_140710.pdf Pilot Program for Climate Resilience. www.climateinvestmentfunds.org/sites/default/files/results-2015/ppcr/index.html#results_201 TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 13 ANNEX 1 A FRAMEWORK FOR PROBABLISTIC RISK ASSESSMENTS Task 5 – Probabilistic Risk Assessment: The risk assessment component uses the outputs of the tasks outlined above and computes the direct losses and downtime caused by each earthquake or tropical cyclone in the stochastic catalogue of simulated future events to each component of the road network. Consequently, it computes whether disruption of service for the entire network is expected and, if so, for how long. If disruption of service is expected for a period (e.g. 2 months) this component will also evaluate the indirect losses to the stakeholders. The direct losses and downtime for each network component are computed by coupling the estimation of the effects of the event at each component location (e.g., a 2-meter tsunami wave at location 1, 2.5 meter at location 2, etc.,) with the damage and downtime functions tailored for the vulnerability class of each component. The absolute value of the direct losses is obtained by multiplying the damage ratio suffered by each component by its replacement value. The computations above were explained as if they were deterministically made based on mean values. However, this is not the case in state-of-the-art models, which account for uncertainty in the predicted values of the effects for each event, and for damage or downtime given the level of the effects. As stated above, these computations are repeated for all the events in the catalogues. The likelihood of occurrence of the loss and downtime distributions computed for any event is simply equal to the annual rate of occurrence of that event that was computed. Computations for all events are recorded and assembled in such a way that the final risk profiles for the road network are obtained. The loss risk profiles can be expressed simply in terms of annual probability of exceeding losses of different amounts (e.g., US$1 million, US$2 million, etc.) caused by tropical cyclones and/or earthquakes. Similarly, for downtime, the risk profiles provide the same information for network disruption of service of different time lengths (e.g., 1 day, 2 days, 1 week, etc.). The risk profiles can be generated for the road network in the ‘as-is’ condition and for all the feasible network variants proposed during the decision-making process and analyzed by the cost-benefit analysis. Note that in the definition of the risk-modeling framework above there was no mention to the scientific uncertainty that analysts necessarily have about their models for describing exposure, hazard and vulnerability. The science is mature, but the empirical data supporting these models is not plentiful. Hence, competing yet legitimate models can be proposed and they would only differ by how the limited data available has been interpreted and utilized. In large-scale, well- funded projects the uncertainty about models (called epistemic uncertainty) is accounted for using an established methodology called the logic-tree approach. This method that combines multiple modeling views of exposure, hazard (as done by United States Geological Survey, for instance, to develop seismic hazard for the United States of America), and vulnerability to obtain multiple alternative views of risk would provide the most comprehensive set of information for decision-making. The effort needed for such a detailed treatment, however, is often beyond the reach of many projects. When the budget does not allow for such detailed approach, it is still important to test the robustness of the solutions chosen to the assumptions made, with a sensitivity analysis along all uncertain dimensions, and to select solutions that provide acceptable performance under multiple assumptions for exposure, vulnerability and hazard distributions. TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 14 ANNEX 2 Examples of Priorities for Climate Resilience An example of summarized actions and outcomes from the short to long-term are provided below based on the experience in Samoa. Short-Term Medium-Term Long-Term Infrastructure  Install protective measures e.g. sea walls  Improve/stabilize  Roll-out of a  Increase road height slopes comprehensive  Improve storm water capacity  Create additional infrastructure  Increase bridge heights cross drainage upgrade plan  Improve pavement standards Design and  Relocate assets along same road  Establish and/or  Plan and invest Planning  Develop alternative evacuation routes upgrade inland routes around inland  Undertake a Vulnerability Assessment  Update the routes and Climate Resilient Road Strategy Vulnerability  Designate “dangerous roads” Assessment and Road  Make use of basic IDF curves Strategy Maintenance  Increase maintenance frequency  Conduct regular  Employ a  Clean drains/culverts prior to cyclones routine and comprehensive  Develop community based contracting preventative maintenance plan model maintenance and policies that  Strengthen asset management systems –  Use surveys and asset are both reactive information sharing (data/statistics) management data to and proactive improve maintenance budget Reform  Review current legislation and policies –  Reflect alternative  Mainstream climate ranging from climate change, inland routes in the change into all adaptation, and maintenance regimes National Strategic applicable policies and practices Investment Plan and operations  Improved standard – Design Basis  Use Vulnerability Memorandum (e.g., using IDF) Assessment to inform  Resolve land acquisition function and coastal infrastructure conflicts management  Address conflicting roles and strategy and vice responsibilities of line ministries in road versa resilience matters  Streamline climate  Enhance cooperation between line change roles and ministries to address climate change responsibilities into across sectors Government TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 15 Capacity  Involve relevant line ministries  Conduct follow-up  Augment in-country Building  Provide training during the Vulnerability training on ability to update Assessment on key processes and tools Vulnerability Vulnerability e.g., GIS, asset management Assessment and Assessment, models, related tools and asset  Integrate specialist management technical advisors to systems increase ‘in-house’ knowledge TRANSPORT KNOWLEDGE NOTE – APRIL 2018 | 16