Abstract Objective This study evaluated the effectiveness and potential safety benefits of a Rural Junction Active Warning System (RJAWS), which uses variable speed limit signs (VSLSs) to temporarily impose a reduced speed limit along the major road when another vehicle is approaching on the minor road or turning into the minor road from the far-side major leg. Methods The RJAWS was trialed at 4 3-leg rural junctions between 2-lane roads in South Australia. A quasi-experimental before–after analysis was conducted. The free-flow speed of vehicles along the junction major approaches was used as an indicator of the risk of a casualty crash with adjacent traffic. Events with activated and nonactivated VSLSs after the RJAWS installation were analyzed separately. Travel speed, speed limit compliance, and the relative risk of a casualty crash were compared. The potential risk of casualty crashes relative to traveling at the default speed limit was calculated based on a known relationship between travel speed and relative casualty risk for rural roads in South Australia. Results When the reduced speed limit signs are activated, the average travel speed along the major road is reduced between 11.3 and 22.1 km/h, with a consequent reduction of the expected average casualty risk between 42% and 65% compared to before the RJAWS installation. . Though compliance with the reduced posted speed limit was low, the RJAWS still proved effective in reducing travel speed because the majority of drivers traveled through the monitored junctions at speeds below the default speed limit when the sign was activated. Conclusions This evaluation indicated that the trialed RJAWS can potentially reduce the risk of fatal and serious injuries at junctions under conditions that may present the opportunity for an adjacent-direction collision with another vehicle. Extending the RJAWS installation to additional junctions is strongly suggested. Further monitoring is needed to determine whether safety benefits are sustained over the long term.

Human-induced climate change and its associated effects have become one of the most significant problems faced by human-kind. The importance of climate change mitigation has been widely recognised by the scientific, commercial and political sectors. Greenhouse gas (GHG) releases have been identified as a major cause of human-induced climate change. Water distribution systems (WDSs), whilst providing an essential service to modern cities, significantly contribute to the

The importance of reducing greenhouse gas (GHG) emissions, which have been linked to human-induced climate change, is gradually being recognized by water utilities. Although multiobjective optimization has been applied by previous literature to minimize cost and GHG emissions associated with water distribution systems (WDSs), this has primarily been achieved by considering design options of pipe size and pump type. Little consideration has been given to the appropriate sizing of storage tanks. As such, this paper aims to investigate the effect of storage tank size on the minimization of cost and GHG emissions associated with WDSs. Increases in storage tank size are considered by increasing the tank reserve size (TRS), i.e., the portion of the storage tank available for system balancing purposes. Because storage tanks are critical to the operation of a WDS, it is necessary to accurately model the operation of a WDS. Although electricity tariffs (ETs) are used to consider the time dependency of pumping operational cost, no such consideration has been given to pumping operational GHG emissions. As such, time-dependent emissions factors are used to calculate pumping operational GHG emissions. To investigate the effect of TRS on the minimization of cost and GHG emissions associated with a WDS, the multiobjective optimization of two WDS case studies is performed. The results show that using different TRSs can affect the optimal pumping operational management of a WDS, and increasing the TRS can result in GHG emissions reductions. However, using a very large TRS is likely to be associated with prohibitive costs. (C) 2015 American Society of Civil Engineers.

While evolutionary algorithms have been applied extensively to water resource problems, there remains a need to unify and consolidate computational and software approaches to solving these problems. In order to facilitate this for the minimization of costs and greenhouse gas emissions of water distribution systems, the water distribution cost-emissions nexus (WCEN) computational software framework is introduced in this paper. The software is freely available and can be easily modified in order to facilitate consistency of modeling, simulation and evaluation within different research studies. In addition, it enables consideration of the time-dependent variation of operational choices, such as emissions factors, electricity tariffs and water demands, which has not been done previously. The utility of the framework is demonstrated for a case study, the results of which show that consideration of such variations can significantly affect optimal design and operational decisions, as well as their costs and GHG emissions.

Human-induced climate change caused by greenhouse gas (GHG) emissions has become a significant concern. Although water distribution systems (WDSs) provide an essential service, they also contribute to the release of GHG emissions through the use of electricity from fossil fuel sources for pumping purposes. In this paper, the reduction of both costs and GHG emissions associated with the pumping operation of WDSs is considered. Actual (time-varying) emissions factors (EFs) for the South Australia electricity grid from February 2011 to January 2012 with a 5-min time step are used to evaluate pumping operational GHG emissions and are compared with the use of an average EF, which does not consider the time dependency of EFs. An estimated (typical) 24-h EF curve, which aims to replicate the important aspects of the time dependency of actual EFs, is developed and compared for use in place of actual EFs, for when the actual variations in EFs cannot be accurately predicted for the future. Additionally, modified estimated 24-h EF curves, representing different amounts of renewable energy (wind generation) penetration, are considered to test the sensitivity of solution development to the magnitude of the variations of time-dependent EFs. Through the multiobjective optimization of pumping operations of a case study WDS, it is shown that solutions found using actual EFs can minimize GHG emissions by moving pumping to low-EF times of the day. Conversely, solutions found using an average EF can only minimize GHG emissions by pumping more consistently during the day. Additionally, solutions found using the estimated 24-h EF curve are very similar to those found using the actual EFs, suggesting that the estimated 24-h EF curve can accurately replicate the important characteristics of the time dependency of EFs and can be used in place of actual EFs to find solutions of reduced pumping operational costs and GHG emissions. Furthermore, solutions found using the modified estimated 24-h EF curves show that the development of solutions is dependent on the magnitude of the variations of time-dependent EFs.

The Battle of the Water Networks II (BWN-II) is the latest of a series of competitions related to the design and operation of water distribution systems (WDSs) undertaken within the Water Distribution Systems Analysis (WDSA) Symposium series. The BWN-II problem specification involved a broadly defined design and operation problem for an existing network that has to be upgraded for increased future demands, and the addition of a new development area. The design decisions involved addition of new and parallel pipes, storage, operational controls for pumps and valves, and sizing of backup power supply. Design criteria involved hydraulic, water quality, reliability, and environmental performance measures. Fourteen teams participated in the Battle and presented their results at the 14th Water Distribution Systems Analysis conference in Adelaide, Australia, September 2012. This paper summarizes the approaches used by the participants and the results they obtained. Given the complexity of the BWN-II problem and the innovative methods required to deal with the multiobjective, high dimensional and computationally demanding nature of the problem, this paper represents a snap-shot of state of the art methods for the design and operation of water distribution systems. A general finding of this paper is that there is benefit in using a combination of heuristic engineering experience and sophisticated optimization algorithms when tackling complex real-world water distribution system design problems. (C) 2014 American Society of Civil Engineers.

The increased release of greenhouse-gas (GHG) emissions associated with human activities causing climate change is one of the most significant problems faced by human-kind. Water distribution systems (WDS), whilst providing an essential service to society, are responsible for the generation of significant amounts of GHGs. In response, the minimization of GHG emissions associated with WDSs has become a research focus. In this paper, a critical review of previous research is provided, summarizing research progress and highlighting research needs in this emergent and important area. This is done within the context of the water distribution system cost-emissions nexus (WCEN) conceptual framework, which is a novel conceptual framework that considers the interaction between all components required to accurately evaluate the costs and greenhouse gas (GHG) emissions associated with water distribution systems (WDSs) in an integrated fashion. Key findings from this review indicate that future research should (1) include the use of time-dependent emissions factors (EFs), which would allow the scheduling of pumps at times of lower emissions intense energy to be considered; (2) include the modeling of seasonally variable water demands; (3) include greater consideration of the hydraulic simulation process, such as using seasonal extended period simulations; (4) include greater consideration of the management of pumping operations at the design stage, instead of solely focusing on changes in infrastructure design to reduce costs and GHG emissions; (5) include consideration of the effects that external policies, such as carbon taxes and present value discounting, have on the trade-offs between costs and GHG emissions.