addressing climate change adaptation in regional transportation plans

Addressing Climate Change Adaptation in Regional Transportation PlansA Guide for California MPOs and RTPAsConduct Criticality AssessmentSome of the more prominent climate change vulnerability and risk assessmentframeworks, such as the FHWA’s Conceptual Model, ask the assessment team todefine the relative criticality of various types and tiers of assets. The recentFHWA pilot projects, initiated in order to test, validate, and refine the Model,demonstrate that a broad range of techniques can be used to establish assetcriticality, from the very qualitative to the very quantitative.Qualitative MethodsUsing Transportation Models for ClimateAdaptation AssessmentsThe multi-agency New Jersey project funded aspart of FHWA’s 2010-2011 Climate ChangeVulnerability Assessment Pilot Program usedspatial analysis to determine how critical eachasset is to achieving the mission and goals of theNew Jersey multi-agency coalition. Becausetransportation infrastructure serves to connectsystem users with their destinations, a destinationbasedapproach was used. The project teamanalyzed data related to jobs and populationdensity at the Traffic Analysis Zone (TAZ) level todetermine which destinations were critical. Thesedata were used to place highway assets into threelevels of “criticality”,: “extreme”, “high”, and “lowand medium”. The “extreme” assets were thosethat were the most critical and would cause majorproblems if they were to fail. The other categoriesdecrease respectively in their level of criticality.Maps displaying these assets according to theircriticality levels were then generated.Source: NJTPA et al. (April 2012).Especially for assessments with smaller study areas or a limited selection ofassets, or for assessment teams with limited technicalresources, a qualitative assessment might suffice. Thisstep may simply involve an extension of the “High LevelCriticality Screening” described previously, wherein astakeholder process is used to establish a dialogue onpriorities. These regional priorities are then translatedinto a limited selection of assets for assessment. Thistechnique was recently adopted by OahuMPO (an FHWApilot) to establish a very constrained list of assets forassessment with limited resources.Quantitative MethodsAssessments of greater scope may require theintroduction of quantitative elements in order to protectagainst unintended omissions and potential errors injudgment relating to the relative importance of one assettype or class versus another.The most basic quantitative technique is to establish asimple numerical scale for rating criticality. Ratings maybe conducted collaboratively as a group (linking to thestakeholder process essential to qualitative criticalityassessments) or separately and then added or averaged.Washington DOT used a 10-point scale to determinecriticality for each major asset as part of its FHWA pilotproject, although the rankings are qualified as beingsubjective and useful primarily as a device in differentiating the rankings.The North Jersey Transportation Planning Authority’s FHWA pilot projectincluded a wide range of roadway assets in the assessment, and thereforeadopted a GIS-based approach to tiering assets by criticality. The assessmentteam developed a destination-based criticality approach, which used jobs andpopulation density for each Traffic Analysis Zone (TAZ) as proxies for criticaldestinations. To account for the magnitude of the connections made by a givenasset, volume or ridership data was also factored in (AADT). Originally, theCambridge Systematics, Inc. 9-13