Taxis play an indispensable role as the main mode of paratransit in many cities in the developing countries. To the best of our knowledge, research on taxi service quality, and certainly studies focusing on developing countries, are quite rare. Using a subjective approach (data collected from passengers), this study examines the main determinants that affect user’s perception of fixed-route taxi services in Shiraz, Iran. The methodology adopted in this study employs principle component analysis (PCA) followed by partial least squares structural equation modeling (PLS-SEM). The results show that among the different attributes of service quality, driver behavior (including components of attitude toward passengers, driving practice, and professionalism) was the strongest determinant of passengers’ overall assessment of the service quality. Service providers and the municipalities that oversee operations can draw on the results of this study to develop future strategies for improving their paratransit services.

Countless cities are rapidly developing across the globe, pressing the need for clear urban-planning and design recommendations geared toward sustainability. This paper examines the intersections of Jane Jacobs’ four conditions for diversity with low-carbon and low-energy-use urban systems in four cities around the world: Lyon (France), Chicago (Illinois), Kolkata (India), and Singapore City (Singapore). After reviewing Jacobs’ four conditions for diversity, the four cities are introduced and their historical development context is described. A framework to study the cities along the following three dimensions is then presented: population and density, infrastructure development/use, and climate and landscape. These cities differ in many respects and their analysis is instructive for many other cities around the globe. Jacobs’ conditions are present in all of them, manifested in different ways and to varying degrees. Overall, the study results show that the adoption of Jacobs’ conditions seems to ...

Using modified bitumen has been one of the few reliable methods adopted for improving asphalt performance against moisture sensitivity. This research offers an approach in which both mechanical methods and micro-mechanism investigations have been employed to study the effect of bitumen modified with epoxy resin on the moisture sensitivity of asphalt mixtures. Six bitumen samples: base bitumen and bitumen modified with 1% to 5% epoxy resins, and two types of aggregates (limestone and siliceous) were selected for this study. Surface Free Energy method and Modified Lottman test were used to investigate the moisture sensitivity of asphalt mixtures containing each bitumen-aggregates combination. In the first method, surface free energy values of bitumen and aggregates were estimated and then used in predicting energy parameters related to the moisture sensitivity parameters, using which the changes in adhesion and wetting properties of each bitumen-aggregates mixture were analyzed. In the second method, the indirect tensile strength test was performed on dry and wet asphalt samples, and the tensile strength ratios were obtained for each asphalt mixture, through which the moisture resistance of samples were investigated. Based on the values obtained for the three parameters, it was concluded that epoxy resin addition decreased the moisture sensitivity of asphalt mixtures containing siliceous aggregates by increasing the bitumen and aggregates adhesion as well as increasing the wetting of the aggregates surface with bitumen. Also, in asphalt mixtures containing limestone aggregates, epoxy resin improved moisture sensitivity, but this improvement was only due to increased adhesion between bitumen and aggregates, while the impact of bitumen coating on aggregates surface did not change significantly with the addition of epoxy resin. Among the asphalt mixtures studied, the highest moisture resistance was observed in asphalt mixture containing 4% epoxy resin, at which the Tensile Strength Ratio parameter showed an increase of 11.3% and 21.5% for limestone and siliceous mixtures, respectively, compared to the base asphalt mixture.

The objective of this study is to investigate the resilience of roads networks to extreme events using a GIS and network science approach. Using the specific case study of Chicago, three extreme event scenarios were simulated: (1) extreme flooding, (2) random zonal disturbance, and (3) central targeted disturbance. To measure their impacts and as a proxy for flows, we calculate and analyze how the betweenness centrality of each road segment is being redistributed in the network before and after each simulation. Moreover, by randomly selecting 100 nodes in the Chicago road system, we simulate 10,000 trips and examine how they are being affected by each extreme event scenario. Overall, we find that extreme events can have tremendous impacts. More importantly, different types of extreme events generate completely different impacts, and the notion of resilience therefore rapidly becomes sensitive to individual contexts, thus supporting the argument towards more scenario-based analyses.

The network structure of an urban transportation system has a significant impact on its traffic performance. This study used network indicators along with several traffic performance measures, including speed, trip length, travel time, and traffic volume, to compare a selection of seven transportation networks with a variety of structures under different travel demand conditions. The selected network structures were modified linear, branch, grid, three-directional grid, one-ring web, two-ring web, and radial. Chosen for the analysis was a base origin–destination matrix to which different multiplier factors were applied to simulate various travel demand conditions. Results show that overall the two-ring web network offered the most efficient traffic performance, followed by the grid and the one-ring networks. A policy application of this study is that the branch, three-directional grid, and radial networks are suited mostly for small cities with uncongested traffic conditions. In contrast, the two-ring web, grid, and one-ring web networks are better choices for large urban areas because they offer more connectivity and thus allow them to perform efficiently under congested traffic conditions.