Journal of Infrastructure Systems

The intensity of the seismic demand in a vulnerability assessment of an engineered system can be described in terms of either its annual probability of being exceeded or a scenario earthquake. A probabilistically stated hazard (e.g., one with a return period of $\mathrm{2,475}\text{years}$ ) represents an aggregation of numerous earthquakes and may not represent the spatial distribution of seismic intensity from a severe earthquake over a region correctly, making its application to performance evaluation of a large-scale distributed civil infrastructure system questionable. A scenario earthquake models the spatial intensity correctly, but conveys no quantitative measure of the seismic risk. This paper examines the use of probabilistic seismic hazard analysis and corresponding scenario earthquakes as a basis for vulnerability assessment of a networked system. Following an examination of simple spatially distributed series and parallel system models, a vulnerability assessment of an electrical power network in a region of moderate seismicity in the Central United States offers additional insight into the issue.

This paper is concerned with infrastructure maintenance and repair policies when the managing agency does not value expenses linearly. Such nonlinearity naturally arises in the stochastic world of reliability engineering, manifesting, for instance, as risk aversion: the ideal maintenance and repair policy has a low cost variance, as well as a low average cost. Another type of nonlinear behavior arises when one tries to match future expenditures with an externally determined budget. Dynamic programing techniques are applied to create two algorithms (FindPolicy and EvalPolicy) which are of use in this problem: FindPolicy determines an optimal maintenance policy, while EvalPolicy allows a previously determined policy to be evaluated according to a broad class of measures of effectiveness. These algorithms are applied to a hypothetical bridge facility and to determine and evaluate short-term and long-term maintenance policies. In this example, large reductions in solution variance are attainable with only slight increases in average cost.

Within the past two decades, the road maintenance concept has been gaining tremendous attention. This has brought about new institutional changes, predominant of which is the challenge for maintenance managers to achieve maximum performance from the existing road system. Such challenge makes it imperative to implement comprehensive systems that measure road maintenance performance. However, as pointed out by the Transportation Research Board, even though the road maintenance performance measurement systems developed and implemented by the state departments of transportation elaborate on the maintenance level of service (i.e., effectiveness of the road maintenance), the fundamental relationships between the maintenance level of service and the budget requirements (i.e., efficiency of road maintenance) need more investigation. This is mainly because not knowing how “efficient” state departments of transportation are in being “effective” can lead to excessive and unrealistic maintenance budget expectations. In an effort to address this need, this research aims to develop and implement a comprehensive framework that can measure the overall efficiency of road maintenance operations. This framework is designed to consider the effects of environmental (e.g., climate, location, etc.) and operational (e.g., traffic, load, etc.) factors on such overall efficiency. This paper introduces the efficiency measurement framework and specifically provides an overview of the data and modeling issues faced during the early stages of the implementation of the framework to the Virginia Department of Transportation’s case for the maintenance of bridges.

A companion paper by the writers introduces the framework that was developed using an approach called data envelopment analysis to measure the overall efficiency of road maintenance operations while considering the effects of environmental and operational factors (both of which are beyond the control of the decision maker, i.e., the maintenance manager) on such overall efficiency. Such paper introduced the data envelopment analysis approach, presented the road maintenance efficiency measurement framework and provided an overview of the data and modeling issues faced during the earlier stages of the implementation of the framework to the Virginia Department of Transportation’s case for the maintenance of bridges. This paper presents the core implementation stages of the framework in trying to identify (1) the relative efficiency of seven counties of Virginia in performing bridge maintenance; (2) the benchmarks (peers) and targets that pertain to the inefficient counties; and (3) the effects of the environmental and operational factors on the road maintenance efficiency of counties. The results and discussions presented in this paper can be used to direct decision makers’ attention to develop a better understanding of the reasons why some counties are more efficient than others.

Motivated by the desire to understand the impact of water supply systems on the environment, a life cycle-based hybrid methodology is used to assess the performance of two conservation scenarios, water efficiency, and rainwater harvesting, relative to the base case. The analysis carried out for the City of Toronto’s residential sector estimates the operational energy use and GHG emissions, and the embodied burdens associated with water-efficient devices and rainwater tanks. Hydraulic simulations, performed on a hypothetical network to expose the impact of demand peak factor on pressure distribution at nodes, revealed some of the rainwater scenario strengths such as hydraulic stress curtailment and capital investment postponement. While both strategies led to significant water savings, the associated energy expenditures and emissions varied with the selection of system boundaries. Nevertheless, both conservation strategies are worthwhile pursuing for rendering the existing water systems more sustainable.

Instability of roadway slopes and embankments is a type of geohazard that can endanger the traveling public and the nearby roadway facilities when large and sudden slope movement occurs. Frequently, the decision regarding managing the hazards associated with potential highway slope failures or incipient failures is based on subjective judgment. In this paper, the linguistic fuzzy theory is used to express the hazard level associated with each selected hazard assessment criterion. The multicriteria decision-making technique is also used in this paper to allow for combination of the hazard criteria involving different units. As an example illustrating the application of the developed method for assessing the hazard level and priority for repair in regard to the slope instability related geohazard, the pertinent information of a database containing 37 landslides sites in Ohio is used to go through the exercise of hazard assessment. From the presented illustrative example, it is shown that the proposed multicriteria decision-making approach promotes a better decision for managing the geological hazards due to roadway slope failures.

Limited resources and drinking water quality requirements pose significant challenges to those managing small and rural drinking water distribution systems (WDSs). Real-time monitoring technologies could support regulatory compliance, if shortcomings such as false readings and data corruption could be overcome. Bayesian belief networks (BBNs) are proposed as a means to mitigate technological shortcomings and increase certainty about the state of a given WDS. This paper describes a methodology for the development of BBNs that integrates known system characteristics with real-time monitoring technologies to support the water quality compliance of small or rural WDSs. Expert judgment was used both in the development of the structure of the BBN and in quantifying the required probability relationships. The results of a case study application of this methodology suggest that it is useful in developing a BBN to support decision making for a WDS with limited use of real-time monitoring technology.

Evaluations of surface distresses in pavements, such as cracking, bleeding, and raveling, are often used as one component of overall pavement condition indexes. Both manual and automated survey methods are available for pavement distress evaluation; however, all distress evaluations experience a certain level of variability in their results. How this level of variability is determined depends on the type of data collected during the pavement distress evaluations. When distress data are collected as ordinal values, the variability may be determined by comparison of pairs of ranked values. This paper presents one rank correlation method, Kendall’s correlation coefficient, and illustrates how it can be used to assess variability in ordinal distress data collected through manual surveys. Using Kendall’s correlation coefficient, variability between different raters and variability between multiple evaluations by one rater were determined for each individual distress type. As a result, the ratings for certain distresses such as bleeding were found to have a high level of variability. This information can be useful when used to develop training programs to reduce data variability.

In cast-iron pipes, chlorine consumption due to internal corrosion is high compared with consumption caused by other water-quality factors in such systems and may be considered as an approximate indicator of the rate of internal corrosion. Herein, a relationship is developed that determines the rate of internal corrosion as a function of the chlorine concentration, the chlorine decay constant, and the velocity of the water in a pipe segment with a given length and diameter. These factors may be considered uncertain at any given time and the probability of mechanical failure due to the thinness of the pipe wall caused by internal corrosion throughout the pipe life is estimated using Monte Carlo simulation, the first-order reliability method, and the second-order reliability method to account for these uncertainties. The results indicate that the likelihood of failure is nearly 50% by the 80th year for a cast-iron pipe length of 6 m and a diameter of 203 mm, and that the affect of internal corrosion on the pipe wall thickness and thus mechanical failure is lower than, but on the same order of magnitude as, the effect of external corrosion.

Studies on benchmarking in water sector are very scarce particularly in the Asian region. None of the studies conducted so far have estimated and aggregated multidimensional performance of urban water utilities that incorporate important sustainability parameters. This paper attempts to fill this gap and evolve suitable sustainability based benchmarking framework to assess aggregate efficiency of 18 Indian urban water utilities using data envelopment analysis approach. The proposed benchmarking framework may be used by the state regulator/operator to rank the utilities, set targets for productivity improvements, and provide performance linked incentives in order to enable sustainable water supply services. The performance analysis of water utilities against the six identified sustainability parameters based on average technical efficiency scores suggests the need for greater attention toward service adequacy, service reliability, and business viability parameters. The analysis on aggregate technical efficiency (TE) and scale efficiency (SE) suggests significant scope for improvement in technology and operational scale and hence cost savings. The study also shows significant scope for reduction in unaccounted for water, i.e., water loss, staff size, and electricity expenditure. Efficiency analysis based on city sizes presents higher TE for medium-sized utilities and higher SE for small-sized utilities.

There is an increasing demand from state DOTs to explore alternative ways to provide adequate oversight on construction projects. As one of the innovative contracting techniques encouraged by the Federal Highway Administration, warranties in highway construction hold contractors accountable for potential maintenance for a given period of time after project completion. The warranty practices in many states indicate that such provisions would benefit the state DOTs by improving quality, reducing life-cycle costs and project duration, and encouraging contractor innovation. However, the successful implementation of warranty contracting needs widespread industry acceptance and collaboration. This paper presents the findings of a recent research on the industry acceptance of warranty contracting in the state of Alabama. The paper identifies several major concerns and the needs of the construction industry with respect to the subject matter. More importantly, the paper reports a learning process in using warranties in highway construction. Results shows that factors like leniency in specifications, tort liability, and contractors’ past experience on warranty jobs help achieve a significance level of industry acceptance. The findings presented in this paper would help those state highway agencies that have limited experience in integrating warranties effectively into their contracts.