Journal of Infrastructure Systems

Estimating the effects of influential factors on pavement service life is an important, but difficult task for highway agencies. In this paper, by specifying a particular pavement condition rating (PCR) as the terminal pavement status, survival curves were developed based on historical PCR data using the Cox proportional hazards (PH) method. Further, the estimated service lives of pavements are obtained from these survival curves. As an example, the survival data of asphalt overlays on flexible pavements in Ohio are analyzed for this study. The effects of influential factors, such as structure thickness, climate, traffic loading, and pavement conditions prior to repair on pavement service life were assessed. The results show that the Cox PH model is applicable in estimating the effects of influential factors on pavement service life. The service life obtained from this study can be used to assist with pavement rehabilitation decision-making, overlay design, and budget allocation.

The water and wastewater sector is currently placed among infrastructure utilities of significance. A key problem with most water and wastewater utilities is the absence of performance assessment tools. This research focuses on the calculation of a group of financial and operational indicators for a sample size of 234 public and private sector utilities from developed and developing countries. These indicators are then used to depict the performance of public versus peer private sector water and wastewater utilities, as well as the performance of Egyptian utilities compared to the remaining companies in the sample. The results furnished by the group of indicators included in the study revealed the resemblance in some performance aspects between water and water/wastewater utilities in Egypt and the remaining developing countries. However, a significant gap was noticed between Egypt and the United States. On the other hand, the study revealed that U.S. and U.K. private-sector water and water/wastewater utilities demonstrated better values compared to the remaining public-sector utilities in some indicators such as the asset turnover ratio and the tariffs charged for water services. In the meantime, the percentage of unaccounted for water and the debt to equity ratio were other indicators that experienced no advantage in private over public sector utilities.

The Inoperability Input-Output Model (IIM) provides a mechanism to enable examination of interdependencies among economic sectors to estimate the effects of a disruptive event. In previous IIM applications, parametric analyses were used to represent uncertain model inputs that created ambiguity in physical interpretations. This paper develops a transportation-based framework for decomposing the IIM inputs into two components: (1) workforce and (2) commodity flows. For workforce analysis, we estimate the number of workers using a particular asset, the normal income level, and the reduced income resulting from a disruption. For commodity analysis, we estimate the value of goods traveling across a particular asset and the resulting reduction due to a disruption. The workforce and commodity formulations were demonstrated using an ex post analysis of the 2003 closure of Virginia’s Midtown Tunnel. The study utilized a computer tool to execute the model and to perform sensitivity analysis to account for the data uncertainties.

Canadian municipalities have noted that 59% of their water systems needed repair and the status of 43% of these systems is unacceptable. In the United States, ASCE assigned a near failing grade of D– to the condition of water system infrastructure. Therefore, municipalities face a great challenge of managing the expected large replacement and new installation projects of water mains. This research aims at designing a robust model in order to assess the condition and predict the performance of water mains. Data are collected from three different Canadian municipalities: (1) Moncton (New Brunswick); (2) London (Ontario); and (3) Longueiul (Québec). An integrated model and framework, using an analytic hierarchy process (AHP) and artificial neural network (ANN), are developed. In addition, an automated, user-friendly, web-based infrastructure management tool (CR-Predictor) is developed based on the integrated AHP/ANN model to assess water main condition. The developed tool and models are validated in which they show robust results (98.51%)—the average validity percent. They are expected to benefit academics and practitioners (municipal engineers, consultants, and contractors) to prioritize inspection and rehabilitation planning for existing water mains.

Public works departments need test procedures for assessing the current condition of concrete in public facilities such as parking garages. Nondestructive testing can provide ultrasonic pulse velocities that can be used as an indicator of concrete quality. A procedure is presented that can be used to collect and analyze ultrasonic measurements. The procedure was applied for all of the public garages in Montgomery County, Md., to identify garages that needed immediate maintenance. Based on the measured data, the effect of the age of the concrete on the pulse velocity was investigated and a model was developed. The model can be used to determine where a garage is in its life cycle. The effect of elastomeric membranes, used to protect the concrete slabs on pulse velocities, was evaluated with the results indicating that the use of membranes extended the life of the concrete by about 10%, or an equivalent of $3\text{years}$ of design life. A method of evaluating the effect of steel reinforcement on the pulse velocity was developed and applied. The method can be used to identify the optimum spacing between the transmitter and receiver in nondestructive testing.

The design and construction industries have an increasing interest in and responsibility for a building’s environmental effects over its entire life cycle. Quantification of all building phases is important in life-cycle assessments (LCAs), especially for the construction phase, which is often disregarded. This research uses an input-output-based LCA framework to create a more comprehensive estimate of the environmental effects of construction processes. The hybrid LCA model is based on Carnegie Mellon University’s Economic Input-Output Life Cycle Assessment (EIO-LCA) tool and combines a new EIO-LCA “hybrid” interface with updated and reformulated environmental effect vectors for EIO-LCA’s 13 construction sectors. Eight construction project case studies modeled on the input-output (I-O)-based hybrid LCA framework demonstrate the model’s broad applicability; gasoline, particulate matter, and global warming potential effects generally increased across all construction sectors and case studies. The I-O-based hybrid LCA model for construction is intended to help decision makers make more informed decisions regarding the construction industry, adding environmental quality and sustainable development as project goals instead of unintentional benefits of economic decisions.

The paper explores the connection between the urban form of water distribution networks and their energy use. Urban form corresponds to the network pipe configuration and the spatial distribution of water users. An analytical model is developed to quantify the energy use to fabricate pipes, to repair pipes, to pump water, and to dispose of pipes in a trunk line. Results show that only a 10% reduction in annual per capita energy is achieved in the trunk line by increasing population density from $10\mathrm{ca}∕\mathrm{ha}\text{to}275\mathrm{ca}∕\mathrm{ha}$ . The analysis is extended by computing energy use in networks with gridiron, radial, and satellite pipe configurations and uniform, monocentric, and polycentric population distributions. On average, the radial/monocentric combination exhibits the lowest annual per capita energy use. The paper is concluded by discussing changes to the form of cities and water main infrastructure to reduce environmental impact.