How to Improve Pavement Life Cycle Cost Analysis: A Case Study of Minnesota

Life cycle cost analysis (LCCA) frameworks are used by some transportation agencies for economic assessment, but there have been challenges implementing the approach, particularly in the characterization of initial and future costs of materials, as well as their associated uncertainties. This research brief presents a case study which focused on characterizing initial and future pay item costs as a function of project size for a probabilistic LCCA of the entire life cycle including user cost impacts.This research was carried out by the CSHub@MIT with sponsorship provided by the Portland Cement Association and the Ready Mixed Concrete Research & Education Foundation. CSHub@MIT is solely responsible for content

Material diversification in pavement management : a technique to proactively deal with an uncertain future

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2016.Cataloged from PDF version of thesis.Includes bibliographical references (pages 123-135).Pavement management systems are important tools that planning agencies depend upon for the effective maintenance of roadway systems. Although uncertainty is an inherent trait of these systems, the current approaches generally exclude its consideration from the analysis. Consequently, decision-makers disregard opportunities to embed sources of flexibility that may be advantageous to deploy if future conditions unfold differently from expectations. One potential source of flexibility available to planners is the incorporation of a broader range of paving materials and designs as part of their pavement preservation strategy. More specifically, this thesis hypothesizes that the inclusion of concrete-based maintenance alternatives by an agency can act as an insurance policy that protects planners at moments of spiraling costs for other paving commodities. To test the hypothesis set forth, this dissertation develops a stochastic simulation model that incorporates uncertainty as it relates to roadway deterioration and the future cost of maintenance actions. Its greedy heuristic algorithm addresses the inability of the current methods to (a) account for the heterogeneous (e.g., material, design, traffic) nature of pavements (b) scale for the type of real-world contexts that planners intend to use pavement management systems and/or (c) allow decisions to be made sequentially over time. The algorithm provides a high fidelity solution that generally falls within 2% of the global optimum for low-dimensional and deterministic problems. Subsequently, the model is applied to the Commonwealth of Virginia's interstate system, whose department of transportation (VDOT) traditionally only maintains their pavements with asphalt-based technologies, to minimize traffic-weighted roughness over a 50-year analysis period. A comparison of the solution for Virginia demonstrates that the DOT could achieve its desired performance goals, on average, at a cost reduction of 10% by incorporating multiple paving materials as part of their pavement management strategy. Results from the simulations indicate that much of the expected benefit from the concrete-based designs stems from their ability to mitigate poor performance at times where asphalt prices are significantly higher than expected. These results suggest that the benefit from incorporating a larger range of paving materials and designs by a planning agency could be much higher than agencies realize using the current deterministic approach for pavement management.by Omar A. Swei.Ph. D

Incorporating uncertainty in the LCCA of pavements

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 81-87).Life Cycle Cost Analysis (LCCA) is an important tool to evaluate the economic performance of alternative investments for a given project. It considers the total cost to construct, maintain, and operate a pavement over its expected life-time. Inevitably, input parameters in an LCCA are subject to a high level of uncertainty, both in the short-term and long-term. Under its current implementation in the field, however, LCCA inputs are treated as static, deterministic values. Conducting such an analysis, although computationally simpler, hides the underlying uncertainty of the inputs by only considering a few possible permutations. This suggests that although computationally simpler, the answer from the analysis may not necessarily be the correct one. One methodology to account for uncertainty is to treat input parameters as probabilistic values, allowing the analysis to consider a range of possible outcomes. There are two major reasons as to why probabilistic LCCAs, although recommended, have not been streamlined into practice. First, the LCCA of construction projects is a large-scale problem with many input parameters with a high-level of uncertainty. Second, there is a significant gap in research that statistically quantifies uncertainty for input values. This research addresses the latter point by statistically quantifying four types of uncertainty: the unit cost of construction, quantity of material inputs, occurrence of maintenance activities, and a particular emphasis is placed upon characterizing the evolution of material prices over time. Having statistically characterized uncertainty in the LCCA analysis, the application of the probabilistically derived inputs is illustrated in three scenarios. Pavement alternative designs are derived for a set of traffic conditions in a given location. The results of the analysis indicate the integration of probabilistic input parameters in the LCCA process allows for more robust conclusions when evaluating alternative pavement designs. Additionally, the case study shows treating input parameters probabilistically could potentially alter the pavement selection, and one parameter that greatly influences this is material-specific price projections.by Omar Abdullah Swei.S.M

Earthquake and deterioration inclusive probabilistic life cycle assessment (EDP-LCA) framework for buildings

With increasing demand to reduce the carbon emission of buildings, it is crucial to quantify the life cycle environmental impact of new buildings, including the environmental impact due to natural hazards, such as earthquakes. This study presents a novel comprehensive probabilistic framework to quantify the environmental impact of buildings, including uncertainties in the material extraction and production, transportation, construction, seismic exposure and aging (including deterioration), and end-of-life stages. The developed framework is used to quantify the environmental impact of a 3-story residential building located in Vancouver, Canada. The results show that there is a significant variation in the environmental impact of the prototype building in each stage of the life cycle assessment. If the prototype building is hit by the design level earthquake, it is expected that the median environmental impact of the prototype will be further increased by 42%. In addition, by accounting for the probability of occurrence of different earthquakes within a 50-year design life of the prototype building, the earthquake related damage will result in an additional 5% of the initial carbon emission of the building. This shows the importance of including earthquake hazard and deterioration in whole building life cycle assessments

Supplementary Information for Comparative Pavement Life Cycle Assessment and Life Cycle Cost Analysis

The MIT Concrete Sustainability Hub (CSHub) is conducting life cycle environmental and cost analyses of pavements under a wide range of contexts. The analyses involve the comparison of new asphalt concrete (AC) and portland cement concrete (PCC) pavement designs for a series of defined scenarios.MIT Concrete Sustainability Hub research is supported by the Portland Cement Association and the Ready Mixed Concrete Research and Education Foundation

Planning strategies to address operational and price uncertainty in biodiesel production

This is a PDF file of an unedited manuscript that has been accepted for publication in Applied Energy. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The final version will be available at https://doi.org/10.1016/j.apenergy.2019.01.19

Methods, Impacts, and Opportunities in the Concrete Building Life Cycle

Life cycle assessment (LCA) offers a comprehensive approach to evaluating and improving the environmental impacts of buildings. This research explores and advances three key areas relevant to the field of buildings LCA: methodology, benchmarking, and impact reduction opportunities.MIT Concrete Sustainability Hub research is supported by the Portland Cement Association and the Ready Mixed Concrete Research and Education Foundation