Transportation Research Part D-transport and Environment最新文献

Identifying subway PM sources is essential to improving subway air quality. To date, no source apportionment studies exist for systems with limited mechanical ventilation. These systems often have high concentrations of PM_2.5. This study investigated PM_2.5 sources in the Toronto subway system using three analytical approaches. Positive matrix factorization identified three subway sources and no outdoor sources. A two-source Chemical Mass Balance (CMB) model apportioned 92% and 55% of PM_2.5 to iron-rich components (wheels, rails, and contact rails & shoes) and 8% and 45% to brake pads on line 1 and 2, respectively. A simple mechanistic model combined with the CMB results revealed wear of wheels, rails, and brake pads during braking to be the main source of PM_2.5 in this subway. These results indicate that below grade subways with minimal mechanical ventilation are dominated by system-sourced PM_2.5 emitted during deceleration. This knowledge should help identify strategies to improve air quality in the subway systems.

Facing frequent impacts from extreme weather such as tsunamis, storms and tropical cyclones, ports suffer from crises of operation shutdowns, shipping traffic jams, commuting obstacles and even manpower shortages. This research focuses on investigating how ports can enhance resilience through forming alliance from the perspective of dynamic evolutionary games. It explores the port’s investment strategy, government guidance for port alliance, and shipping companies’ decision to alleviate the damages from extreme weather attack, particularly with the consideration of stochastic risks. The study examines key factors including investment in resilience enhancement, port changing, vessel detentions, government subsidy and reputation. By analyzing the evolutionary process, evolutionary rate, stable states and stochastic disturbances, the research reveals the dominant strategies under various conditions, resilience enhancement priority, threshold condition for port changing, optimal subsidy strategy, and the impacts of various risks. The findings would offer valuable theoretical insights and practical guidance to port management.

Transport infrastructure construction and its future expansion is a worldwide phenomenon. Within road ecology, scientific attention has focused on effectiveness of mitigation measures for reducing human-wildlife conflict, essentially an ex-post evaluation approach. This work applies a different conceptual framework: an ex-ante approach paying attention to underlying causes of sub-optimal mitigation, typically found in decision-making procedures. The purpose of the study was to determine whether the emphasis on road ecology mitigation measures changed over time. This study considers 52 road projects in the Czech Republic for which the EIA process was initiated between 2003 and 2022. The survey found a low number of EIA processes where these types of mitigation measures were proposed, although over time the frequency increased mainly at the stage of biological survey. Number of processes where landscape permeability for wildlife movement was assessed also increased over time. Coordinating solutions for human-wildlife conflicts across stages and including road ecology criteria in decision-making processes is essential.

Transport policies targeting emission reduction and air quality improvement typically discourage private car use and promote shifts to mass transit (bus, metro). However, possible increase of travelers’ exposure while adapting to those policies have often been overlooked, which is addressed in this work via a case study of Heavy Pollution Episodes (HPEs) in Chengdu, China, using city-scale traffic camera and transit ridership data. By investigating traffic fluctuation and modal shift under prolonged license plate rationing for private cars and free or discounted fare for mass transit, we show that the reduction of small car traffic was marginal (up to 2.3 % in 24-hour periods), which, environmental benefits wise, is negligible according to air quality modelling. Meanwhile, over 3.23 % of car users switched to mass transit during Orange-level alerts, with a higher degree (by 19 %–39 %) of exposure to PM_2.5. Our findings highlight the importance of exposure-centric decision making during HPEs.

Electric bikes (e-bikes) can play a vital role in sustainable transportation and reducing car dependence. However, questions persist regarding the extent to which e-bikes contribute to replacing and complementing car use and other modes, especially from dual-mode ownership (households with both cars and e-bikes) perspective. Utilizing the Household Travel Survey dataset from Jiading, Shanghai, this study reveals that: (1) e-bikes can lead up to a 19% reduction in car mode share in dual-mode ownership households compared to car-only households; (2) e-bikes encourage a greater variety of non-commuting activities compared to car-only households; (3) e-bikes have a minor negative effect on public transport mode share, while e-bikes enhance mobility for older people. Overall, these findings underscore the importance of e-bikes in reducing car dependence and achieving development goals towards sustainable transportation and age-friendly cities.

Online retail is characterized by an increasing emphasis on shorter delivery times, which often comes with high logistics costs and a negative environmental impact. Conversely, longer order fulfillment times improve cost and eco-efficiency. This paper investigates whether customers in German-speaking countries are willing to wait longer for their online orders in the fashion, shoes, and accessories sector when offered incentives in return. The research employed an online survey using a within-subjects design. Results indicate that incentives significantly extend customers’ patience. Savings on shipping costs and information on the reduction in CO${}_2$ emissions greatly impact willingness to wait. Personal traits like gender, age, eco-awareness, and order urgency affect incentive responses. This demonstrates customers’ readiness to make trade-offs in delivery time and emphasizes the importance of explicitly addressing the ecological impact of delivery. Suggestions for online retailers and logistics include slower delivery choices and customized incentives aligned with target audience and market.

Road centerline and maximum inundation depth methods have been used in most previous studies to assess road waterlogging, but accurately expressing the spatiotemporal characteristics of road waterlogging is difficult. To address this issue, a new multilevel road waterlogging assessment model based on four spatial scales and four assessment indices was developed. Then, a road waterlogging information acquisition method was designed based on flood models (FMs) and spatial analysis methods, and existing multihierarchical road network models (RNMs) were extended to integrate road waterlogging information. Next, with a typical region selected as the study area, road waterlogging information under specific rainstorm scenarios was acquired and analyzed with the FMs and RNMs. Then, a multilevel assessment of road waterlogging and various analyses were conducted. The case study showed that compared to traditional models, the new model improved the prediction of the spatiotemporal characteristics of road waterlogging.

The sailing environment has a significant impact on the microscopic characteristics of ship emissions. A portable emission measurement system was used to measure and quantify the emission characteristics of two ships using different energy types in the Yangtze River. The effects of the key influencing factors, waterway environment, operating conditions, and fuel type on ship emissions were investigated. The reasonable control of ship speed, acceleration and engine revolution speed and torque can reduce ship exhaust emissions. The use of liquefied natural gas (LNG) can substantially increase CO emissions. The emission levels of the ship during departure and berthing were higher than that during cruising. As an alternative fuel, LNG may increase CO emissions; hence fuel selection requires careful consideration. This study provides key information for the development of effective emission reduction measures and can facilitate the adaptation of inland waterway shipping to low-carbon policies and the mitigation of the associated environmental impacts.

Current best practice aircraft noise calculations primarily focus on strategic noise mapping to assess compliance with legal noise limits. To date, the effects of shielding by buildings or reflections from buildings, forests or cliffs have not been considered in noise mapping, despite their potential impact on results, particularly in mountainous and/or densely built urban areas. In this study, the effects of shielding by buildings and reflections from buildings, forests and cliffs on aircraft noise results were assessed. Calculations were performed with the sonAIR simulation tool for a residential area close to the runway of a military airfield in a mountain valley in Switzerland. The calculations revealed that shielding and reflections may locally strongly affect the results. While this may yield valuable insights for special investigations, calculations without accounting for these effects are still recommended for large-scale noise mapping, to obtain a better overview of the noise exposure and legal compliance.

The transportation sector must adopt cleaner alternatives to meet global emission reduction goals and attain net-zero emissions by 2050. Hydrogen stands out as a promising solution for decarbonizing the railway sector. This study conducts an economic assessment of hydrogen locomotives, considering their entire life cycle. Life cycle costs are analyzed across various travel scenarios and life stages. For shorter distances, the operational phase and capital costs of retrofitting components contribute 64% and 21% to the total life cycle costs, respectively. In contrast, longer distances are dominated by the operational phase, representing nearly 90% of the total costs. Clean hydrogen must reduce costs to compete with diesel locomotives, as only non-sustainable hydrogen currently matches diesel operational expenses. Anticipated advancements in hydrogen technology are expected to make clean hydrogen more accessible, leading to a significant reduction in the life cycle costs of hydrogen locomotives.