AbstractAccessibility, or the ease to participate in activities and obtain resources in a given environment, is crucial for evaluating transportation systems. Greater accessibility is often achieved by increasing individuals' potential mobility. However, potential mobility, if realized by motorized modes, can also generate negative environmental impacts such as fossil fuel consumption and greenhouse gas (GHG) emissions. While the negative environmental impacts of greater mobility are acknowledged, there has been a lack of research to validate those impacts using empirical data, especially considering variations in individuals' mobility levels. This paper presents a method for estimating the expected environmental costs of accessibility represented by a network-time prism (NTP). A NTP delimits all accessible locations within a network and the available time for an individual to present at each location given a scheduled trip origin and destination, a time budget and the maximum achievable speeds along network edges. Estimating the expected environmental costs of a NTP involves three steps: (1) semi-Markov techniques to simulate the probabilities to move along network edges at given times; (2) the speed profiles for reachable edges, and (3) a cost function that translates speeds into environmental impacts. We focus on air quality and employ the motor vehicle emission simulator MOVESLite to estimate the CO2 emissions at both the edge and prism levels. We calibrate and validate the methods for experimental NTPs defined within the Phoenix, AZ, USA road and highway network using vehicles instrumented with GPS-enabled onboard diagnostic devices (OBD). We demonstrate the effectiveness of our method through two scenarios and investigate the impact of changes in mobility levels on the expected CO2 emissions associated with the experimental NTPs.
HighlightsEstimate the expected environmental costs of space-time accessibility via network-time prisms (NTPs).Model the movement dynamics within a NTP under space-time constraints.Collect primary speed and energy consumption data for empirical NTPs in Phoenix, Arizona USA.Validate the expected NTP movement dynamics and CO2 emissions using primary data.Conduct scenario analysis to show the effectiveness of proposed methods in sustainable transportation policy and planning.
Green accessibility: Estimating the environmental costs of network-time prisms for sustainable transportation planning
Journal of Transport Geography ; 64 ; 109-119
2017-08-20
11 pages
Article (Journal)
Electronic Resource
English
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