Identification and assessment of potential wind energy project sites in the State of Maryland

Gemstone Team Renewables

Essays on the Effects of Social Insurance for Disability

This dissertation examines how social insurance, family support and work capacity enhance individuals' economic well-being following significant health and income shocks. I first examine the extent to which the liquidity-enhancing effects of Worker's Compensation (WC) benefits outweigh the moral hazard costs. Analyzing administrative data from Oregon, I estimate a hazard model exploiting variation in the timing and size of a retroactive lump-sum WC payment to decompose the elasticity of claim duration with respect to benefits into the elasticity with respect to an increase in cash on hand, and a decrease in the opportunity cost of missing work. I find that the liquidity effect accounts for 60 to 65 percent of the increase in claim duration among lower-wage workers, but less than half of the increase for higher earners. Using the framework from Chetty (2008), I conclude that the insurance value of WC exceeds the distortionary cost, and increasing the benefit level could increase social welfare. Next, I investigate how government-provided disability insurance (DI) interacts with private transfers to disabled individuals from their grown children. Using the Health and Retirement Study, I estimate a fixed effects, difference in differences regression to compare transfers between DI recipients and two control groups: rejected applicants and a reweighted sample of disabled non-applicants. I find that DI reduces the probability of receiving a transfer by no more than 3 percentage points, or 10 percent. Additional analysis reveals that DI could increase the probability of receiving a transfer in cases where children had limited prior information about the disability, suggesting that DI could send a welfare-improving information signal. Finally, Zachary Morris and I examine how a functional assessment could complement medical evaluations in determining eligibility for disability benefits and in targeting return to work interventions. We analyze claimants' self-reported functional capacity in a survey of current DI beneficiaries to estimate the share of disability claimants able to do work-related activity. We estimate that 13 percent of current DI beneficiaries are capable of work-related activity. Furthermore, other characteristics of these higher-functioning beneficiaries are positively correlated with employment, making them an appropriate target for return to work interventions.

Assessment and Life-Cycle Analysis of Recycled Materials for Sustainable Highway

Recycled materials replacing part of virgin materials in highway applications has shown great benefits to the society and environment. Beneficial use of recycled materials can save landfill places, sparse natural resources, and energy consumed in milling and hauling virgin materials. Low price of recycled materials is favorable to cost-saving in pavement projects. Considering the availability of recycled materials in the State of Maryland (MD), four abundant recycled materials, recycled concrete aggregate (RCA), recycled asphalt pavement (RAP), foundry sand (FS), and dredged materials (DM), were studied. A survey was conducted to collect the information of current usage of the four recycled materials in States’ Department of Transportation (DOTs). Based on literature review, mechanical and environmental properties, recommendations, and suggested test standards were investigated separately for the four recycled materials in different applications. Constrains in using these materials were further studied in order to provide recommendations for the development of related MD specifications. To measure social and environmental benefits from using recycled materials, life-cycle assessment was carried out with life-cycle analysis (LCA) program, PaLATE, and green highway rating system, BEST-in-Highway. The survey results indicated the wide use of RAP and RCA in hot mix asphalt (HMA) and graded aggregate base (GAB) respectively, while FS and DM are less used in field. Environmental concerns are less, but the possibly low quality and some adverse mechanical characteristics may hinder the widely use of these recycled materials. Technical documents and current specifications provided by State DOTs are good references to the usage of these materials in MD. Literature review showed consistent results with the survey. Studies from experimental research or site tests showed satisfactory performance of these materials in highway applications, when the substitution rate, gradation, temperature, moisture, or usage of additives, etc. meet some requirements. The results from LCA revealed significant cost savings in using recycled materials. Energy and water consumption, gas emission, and hazardous waste generation generally showed reductions to some degree. Use of new recycled technologies will contribute to more sustainable highways.