Abstract
Space-time prism (STP) is a comprehensive and powerful model for computing accessibility to urban opportunities. Despite other types of accessibility measures, STP models capture spatial and temporal dimensions in a unified framework. Classical STPs assume that travel time in street networks is a deterministic and fixed variable. However, this assumption is in contradiction with the uncertain nature of travel time taking place due to fluctuations and traffic congestion. In addition, travel time in street networks mostly follows non-normal probability distributions which are not modeled in the structure of classical STPs. Neglecting travel time uncertainty and disregarding different types of probability distributions cause unrealistic accessibility values in STP-based metrics. In this way, this paper proposes a spatiotemporal accessibility model by extending classical STPs to non-normal stochastic urban networks and blending this modified STP with the attractiveness of urban opportunities. The elaborated model was applied on the city of Isfahan to assess the accessibility of its traffic analysis zones (TAZs) to Kowsar discount retail markets. A significant difference was found between the results of accessibility values in normally and non-normally distributed networks. In addition, the results show that the northern TAZs had larger accessibility level compared to the southern ones.
Highlights
Accessibility is a key concept in urban planning, transportation geography, and other related fields
Considering pros and cons of the above-mentioned measures and due to the importance of developing person-based metrics [63,64] and comprehensiveness of space-time prism-based accessibility models [9], this paper aims to develop a spatiotemporal accessibility model for tackling the question of how accessibility to urban opportunities could be calculated in uncertain networks? responding to this question entails addressing the precedent question of how space-time prisms could be constructed in stochastic networks with non-normal travel time distributions? This way, Section 2 outlines model development
This model incorporates network-based space-time prisms that could be implemented on stochastic networks with non-normal travel time distributions
Summary
Accessibility is a key concept in urban planning, transportation geography, and other related fields. Gravity-based measures, first introduced by the groundbreaking work of Hansen [3], moved the previous models forward by considering the assumption that all available opportunities obtained from distance- and cumulative-based measures are not accessible In this type of measures, available activities are weighted based on some variables such as: Attractiveness and travel expenses [28,29]. Distance-, cumulativeand gravity-based measures are aggregate in nature and are unable to describe the intricacy of an individual’s preferences and the space-time restrictions [36,37] These traditional metrics are not suitable for modeling accessibility in multi-purpose and multi-stop trips [38].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
