Journal of Infrastructure Systems

Given the rising concerns over scarce energy resources and global climate change, life-cycle inventories focusing on energy use and greenhouse gas (GHG) emissions were developed for the City of Toronto municipal water treatment system (WTS). Three processes within the facility use phase of the life cycle were considered: Chemical production, transportation of materials, and water treatment plant operation. The impacts of chemical manufacturing were estimated using the economic input-output life-cycle assessment model, while the inventories for transportation and operational environmental effects were based on data from the GHGenius model and regionally averaged data. Operational burdens, 60% of which are attributed to on-site pumping, accounted for 94% of total energy use and 90% of GHG emissions. By contrast, transportation-related energy use and emissions were deemed insignificant. The normalized energy use of the studied WTS was found to be between 2.3 and $2.5\mathrm{MJ}∕{\mathrm{m}}^3$ of water treated. Water conservation practices are recommended as abatement strategies for the energy use and GHG emissions associated with water treatment. The limitations and uncertainties introduced by selected model parameters and through combining various estimation methodologies are discussed, as is the model’s relevance.

Two different sized hydropower projects in China, one with a capacity of $44\mathrm{MW}$ and the other of $\mathrm{3,600}\mathrm{MW}$ , were examined through life-cycle assessment (LCA) from the perspective of both sustainability and environmental impact and the influence of project scale. Using the economic input-output based LCA approach, energy use and greenhouse gas (GHG) emissions were quantified. The resulting energy payback ratios were found to be 7 and 48, whereas the normalized GHG emissions were 44 and $6\mathrm{g}$ $\mathrm{C}{\mathrm{O}}_2$ equivalent per kW h of electricity production, both in favor of the larger project. Compared with published data on other renewable and nonrenewable options, temperate hydropower, particularly large hydropower, is indicated as an efficient electrical source with relatively low GHG emissions.

Community water systems (CWS) are facing significant external forces for change from decreasing water-resource availability, stricter water-quality regulations, decreasing levels of federal subsidy, increasing public scrutiny, decreasing financial health, and increasing infrastructure replacement costs. (The Environment Protection Agency defines a community water system as a public water supply service that serves at least 25 people or 15 connections year round.) The combination of these external forces necessitate increasing consolidation responses by small CWS. The results of the consolidation response are significant economy of scale benefits such as the elimination of service duplication and greater buying power through bulk-rate purchasing. However, the consolidation and subsequence operations of small CWS as a regional water system (RWS) requires the development of a method for comparative performance assessment and evaluation that facilitates open and transparent decision making. (A regional water system is defined as a collection of similar CWS that operate under a single governing authority.) The goal of this paper is to propose such a method for comparative PAE for consolidating CWS that operate as a RWS. The objectives of the paper are: (1) to propose a standard efficiency metric (SEM) parameter for the performance assessment of CWS; (2) to propose a standard efficiency comparison metric (SECM) parameter for the summative evaluation of performance that permits benchmarked comparison among CWS; and (3) to demonstrate how the proposed SEM and SECM parameters promote open and transparent decision making within the RWS.

Certain types of compost materials have fibrous characteristics that exhibit moisture affinity suggesting that they could be used to stabilize expansive soils to control desiccation cracks. In order to understand shrinkage cracking control mechanisms of compost amended soils, a field study was designed with two compost types, dairy manure compost (DMC) and biosolids compost (BSC). Composts were mixed with topsoil at different proportions to form four types of compost manufactured topsoils (CMTs). Seventeen CMT test plots of different treatment widths and thicknesses including a control plot with no CMT cover material were constructed at Stephenville, Tex. and these sections were heavily instrumented with moisture and temperature sensors. Data from sensors, digital image based surface cracking studies, visual observations of shoulder cracking, and surficial erosion surveys of all test sections were collected and statistically analyzed and these results indicated that the BSC amendments provided the best subsoil enhancements by controlling moisture and temperature fluctuations from the high temperature environment, thereby reducing shrinkage cracks in subsoils and in the adjacent paved highway shoulders. The DMCs were less effective in mitigating shrinkage cracking due to low amounts of fibrous or organic matter. Both design and construction specifications for CMTs were also developed. This application will enhance recycling efforts by converting wastes into usable compost, mitigate future pavement cracking, and lessen premature maintenance costs.

The Inoperability Input-Output Model (IIM) was developed to help understand infrastructure interdependencies. Based on the Leontief Input-Output Model, the IIM approximates the physical interdependencies of infrastructures from the economic input-output transactions of sectors. The model is demand-driven, wherein perturbations to the final demand levels are considered the initiating event, and the impact to sectors’ production outputs are the direct and indirect effects resulting from sector interdependencies. This paper presents two other perspectives—supply-side and output-side—to supplement and complement the demand-driven IIM. These two perspectives help address initiating perturbations related to input factors (value added) and to the sectors’ output levels. Further, these perturbations can be in terms of either quantity or price changes, defining the demand-quantity and supply-price models. Finally, the demand-, supply-, and output-side models are integrated using a sequential perturbation approach. A case study using the Virginia 1997 I-O accounts is presented, where it was shown that the different perturbation classes (demand or supply, quantity or price) yield different rank orders of sectors impacted by the initiating event, thus providing various perspectives of impacts.

A majority of U.S. and international roads are low volume. Pavements on these roads, which are often owned or managed by local agencies with limited resources, represent a large transportation infrastructure asset and could benefit from lower life-cycle costs and better performance. The concept of long-lasting or “perpetual” pavements, often applied to high-volume pavements, is likely to produce similar benefits for low-volume pavements. Careful consideration of current long-lasting pavement research and existing practice can produce a straightforward set of best practices for use by local agency practitioners in designing, constructing, preserving, financing, and marketing long-lasting low-volume pavements. These best practices are (1) a maximum traffic loading; (2) a minimum subgrade support; (3) a minimum pavement structure; (4) construction quality; (5) financing; and (6) marketing. A case study involving the city and county of Honolulu illustrates how these best practices can be put into use in developing and implementing a long-lasting low-volume pavement strategy.

Lately project delivery methods where the implementer offers broader service packages are increasingly used in infrastructure projects worldwide. At the same time, the number of alternative project delivery methods has increased making selection of the best one difficult. The road authority must understand the features of the methods in order to select the most effective ones in terms of economic efficiency. To assist in the selection, this research compared the operating principles and performance of design–bid–build, construction management, design–build (DB), and design–build–maintain (DBM) based on an international interview survey and an extensive literature review. Opinions presented by the interviewees and literature review all pointed to the same direction. Based on the analysis of road procurement, broader service packages give, on average, better value for the money and enable clients to attain their goals better than more traditional methods. DB and DBM seem to outperform more conservative procurement methods both in cost and value generation terms. Each method, however, is particularly suitable for specific projects and should be selected accordingly.

This paper reports on a long-term bridge monitoring program in Connecticut. Monitoring systems have been designed and installed on a series of different bridges, beginning in 1999. Ambient data are collected from normal traffic, using strain gauges, accelerometers, tiltmeters, and thermocouples. This paper discusses three of the monitored bridges, demonstrating the benefits of using long-term monitoring systems to provide information on the structural performance that is useful both to those responsible for the bridge infrastructure and to researchers interested in bridge monitoring. The extensive data developed from multiyear monitoring have been used to create benchmarks for passive structural health monitoring for each of the three bridges. Relationships and trends discovered for each of the bridges, used for the creation of the benchmarks, and stored in a database, are discussed.