Towards the Incorporation of Environmental Impacts into Pavement Management Systems

Environmental nuisances (such as greenhouse gases and noise) may be generated during the use phase of the pavement life cycle, with these known to significantly affect the environment. However, no attempt has yet been made to gather information concerning the processes involved in the generation of environmental impacts, and to evaluate them. To address this issue, this paper reviews the knowledge base and relevant methods relating to environmental impact assessment and pavement management. It then presents a conceptual model, integrating impact pathway approach and life cycle cost analysis principles and providing a comprehensive framework for quantification and incorporation of environmental impacts into pavement management. This study shows that pavement management influences environmental impacts occurring during the use phase of the pavement life cycle. It establishes causal links between pavement management and nuisance generation, between nuisances and their impact on receptors, and finally between these impacts and their costs. This study also suggests that incorporating environmental impacts into pavement management systems is feasible and describes how existing and future methodologies and tools may be integrated to support this incorporation. Finally, this study underlines that the inaccuracy of current knowledge and data limits the scope of this conceptual model to network-level decisions.     

The multi-objective network design problem using minimizing externalities as objectives: comparison of a genetic algorithm and simulated annealing framework

Incorporation of externalities in the Multi-Objective Network Design Problem (MO NDP) as objectives is an important step in designing sustainable networks. In this research the problem is defined as a bi-level optimization problem in which minimizing externalities are the objectives and link types which are associated with certain link characteristics are the discrete decision variables. Two distinct solution approaches for this multi-objective optimization problem are compared. The first heuristic is the non-dominated sorting genetic algorithm II (NSGA-II) and the second heuristic is the dominance based multi objective simulated annealing (DBMO-SA). Both heuristics have been applied on a small hypothetical test network as well as a realistic case of the city of Almelo in the Netherlands. The results show that both heuristics are capable of solving the MO NDP. However, the NSGA-II outperforms DBMO-SA, because it is more efficient in finding more non-dominated optimal solutions within the same computation time and maximum number of assessed solutions.     

PM2.5 and NOx from traffic: Human health impacts,external costs and policy implications from the Belgian perspective

This article employs an optimized impact pathway approach to marginal external health costs that relies on high-resolution dispersion models calibrated for Belgium and the surrounding areas. Per tonne, the MEHC_PM2.5 is found to be many times larger than MEHC_NOx, which is currently negative. Further, the impact of Belgian PM_2.5 emissions in the immediate area of generation is significantly larger than the impact on more distant areas; the opposite is true for NO_x. The MEHCs of both pollutants are predicted to increase in the coming years. Further analysis of the impacts of PM_2.5 and NO_x reveals that, on average, modern gasoline vehicles outperform their diesel counterparts as far as future emissions are concerned. This contrasts with findings for 2007, which suggested that Euro 5 diesels had fewer associated health costs because of the potential for ozone reduction offered by their NO_x emissions.     

Applying activity-travel data for the assessment of vehicle exhaust emissions: Application of a GPS-enhanced data collection tool

This paper describes the development of a global positioning system, enhanced data collection tool for the assessment of vehicle exhaust emissions. This involves the collection of activity and travel data on a personal digital assistant with built-in global positioning system receiver. By converting the second-by-second global positioning system based travel data into emissions, estimates are made of the exhausts produced by individual vehicle trips. Differences in travel behaviour and vehicle emissions were examined by gender and trip purpose.