308 research outputs found
Recovery time and propagation effects of passenger transport disruptions
No full textWe propose a method to evaluate public transport network vulnerability. We study the evolution of the passenger Volume Over Capacity (VOC) ratio throughout the network to measure the spatial and temporal extent of the impacts caused by an unplanned service segment disruption. The VOC ratio provides an indication of the on-board travel comfort, an important level-of-service indicator, as well as reflects the residual capacity for absorbing additional demand. Because of the dynamic nature of public transport systems, disturbances propagate through the network in both time and space. Our modelling approach is able to capture transit system dynamics and quantify the extent to which the network exhibits spillover effects. We apply the method to the case of the rapid public transport system of Stockholm Sweden We demonstrate how the changes in network saturation and the corresponding recovery time can be quantified.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport and Plannin
sj-docx-1-trr-10.1177_03611981221119192 – Supplemental material for Who is More Likely (Not) to Make Home-Based Work Trips During the COVID-19 Pandemic? The Case of Scotland
No full textSupplemental material, sj-docx-1-trr-10.1177_03611981221119192 for Who is More Likely (Not) to Make Home-Based Work Trips During the COVID-19 Pandemic? The Case of Scotland by Torran Semple, Grigorios Fountas and Achille Fonzone in Transportation Research Record</p
Study of the accessibility inequalities of cordon-based pricing strategies using a multimodal Theil index
No full textThe implementation of an appropriate pricing policy in an urbanarea could alleviate both environmental and congestion problemsby encouraging a shift towards more sustainable modes oftransportation. However, any positive net social welfare balancedelivered by the policy can hide unacceptable regressive effects.Therefore, it is crucial to investigate any change in relative levelsof accessibility among different categories of transport networkusers.This study focuses on the application of a cordon-basedcongestion pricing scheme on a multimodal network, whereprivate cars and public transportation coexist, and includes asensitivity analysis by varying the size of the charging area andthe amount of the toll, for a monocentric urban reality. Takinginto account an elastic demand associated with each proposedcharging scenario, the related distributional effects are exploredusing the Theil index, with a quantitative assessment of theinequalities in the accessibility variations across the users of thenetwork
From Transit Systems to Models: Data Representation and Collection
No full textThis chapter deals with the data that form input and output of passenger route choice models. All information
about supply and demand that is relevant for passenger route choice must be captured in a formal way in
order to be accessible to mathematical choice models. Over time standard conventions for this formalization
have emerged. In order to avoid repetition in Part 3 they are presented once in Section 5.1. Similarly Section
5.2 formalizes the output of route choice models as quantitative indicators which are then fed back into
higher-level decision models and ultimately into the evaluation of different investment options. Finally,
Section 5.3 reviews real-world data sources from which either model input can be extracted or against which
model output can be compared for validation and calibration. Here the impact of ITS is particularly visible, as
availability, diversity and volume of data have increased rapidly
Aberrant behaviors of drivers involved in crashes and related injury severity: Are there variations between the major cities in the same country?
No full textCrash data analyses based on accident datasets often do not include human-related variables because they can be hard to reconstruct from crash data. However, records of crash circumstances can help for this purpose since crashes can be classified considering aberrant behavior and misconduct of the drivers involved. In this case, urban crash data from the 10 largest Italian cities were used to develop four logistic regression models having the driver-related crash circumstance (aberrant behaviors: inattentive driving, illegal maneuvering, wrong interaction with pedestrian and speeding) as dependent variables and the other crash-related factors as predictors (information about the users and the vehicles involved and about road geometry and conditions). Two other models were built to study the influence of the same factors on the injury severity of the occupants of vehicles for which crash circumstances related to driver aberrant behaviors were observed and of the involved pedestrians. The variability between the 10 different cities was considered through a multilevel approach, which revealed a significant variability only for the inattention-related crash circumstance. In the other models, the variability between cities was not significant, indicating quite homogeneous results within the same country. The results show several relationships between crash factors (driver, vehicle or road-related) and human-related crash circumstances and severity. Unsignalized intersections were particularly related to the illegal maneuvering crash circumstance, while the night period was clearly related to the speeding-related crash circumstance and to injuries/casualties of vehicle occupants. Cyclists and motorcyclists were shown to suffer more injuries/casualties than car occupants, while the latter were generally those exhibiting more aberrant behaviors. Pedestrian casualties were associated with arterial roads, heavy vehicles, and older pedestrians
The influence of traffic, geometric and context variables on urban crash types: a grouped random parameter multinomial logit approach
No full textNumerous road safety studies have been dedicated to the estimation of crash frequency and injury severity models. However, previous research has shown that different factors may influence the occurrence of crashes of different types. In this study, a dataset including information from crashes occurred at segments and intersections of urban roads in Bari, Italy was used to estimate the likelihood of occurrence of various crash types. The crash types considered are: single-vehicle, angle, rear-end and sideswipe. Models were estimated through a mixed logit structure considering various crash types as outcomes of the dependent variable and several traffic, geometric and context-related factors as explanatory variables (both site- and crash-specific). To account for systematic, unobserved variations among the crashes occurred on the same segment or intersection, the grouped random parameters approach was employed. The latter allows the estimation of segment- or intersection-specific parameters for the variables resulting in random parameters. This approach allows assessing the variability of results across the observations for individual segments/intersections.Segment type and the presence of bus lanes were included as explanatory variables in the model of crash types for segments. Traffic volume per entering lane, total entering lanes, total number of zebra crossings and the balance between major and minor traffic volumes at intersections were included as explanatory variables in the model of crash types for intersections. Area type was included in both segment and intersection models. The typical traffic at the moment of the crash (from on-line traffic prediction tools) and the period of the day were associated with different crash type likelihoods for both segments and intersections. Significant variations in the effect of several predictors across different segments or intersections were identified. The applicability of the study framework is demonstrated, in terms of identifying roadway sites with anomalous tendencies or high-risk sites with respect to specific crash types
A study of herding behaviour in exit choice during emergencies based on random utility theory.
No full textModelling human behaviour in emergencies has become an important issue in safety engineering. Good behavioural models can help increase the safety of transportation systems and buildings in extreme situations like fires or terrorist attacks. Although it is well known that the interaction with other decision makers affects human behaviour, the role of social influences during evacuations still needs to be investigated. This paper contributes to fill this gap by analysing the occurrence of Herding Behaviour (HB) in exit choice. Theoretical explanations of HB are presented together with some modelling approaches used in different fields where HB is relevant. A discrete choice stated preference experiment is then carried out to study the role of HB in the decision-making process concerning exit choice during evacuation. A binary logit model is proposed showing that the occurrences of HB are affected by both environmental and personal factors. In particular, the model shows that the personal aptitude to HB can have a key role in selecting an exit
Time-dependent Hyperstar algorithm for robust vehicle navigation
No full textThe vehicle navigation problem studied in Bell (2009) is revisited and a time-dependent reverse Hyperstar algorithm is presented. This minimises the expected time of arrival at the destination, and all intermediate nodes, where expectation is based on a pessimistic (or risk-averse) view of unknown link delays. This may also be regarded as a hyperpath version of the Chabini and Lan (2002) algorithm, which itself is a time-dependent A* algorithm. Links are assigned undelayed travel times and maximum delays, both of which are potentially functions of the time of arrival at the respective link. Probabilities for link use are sought that minimise the driver's maximum exposure to delay on the approach to each node, leading to the determination of a pessimistic expected time of arrival at the destination and all intermediate nodes. Since the context considered is vehicle navigation, the probability of link use measures link attractiveness, so a link with a zero probability of use is unattractive while a link with a probability of use equal to one will have no attractive alternatives. A solution algorithm is presented and proven to solve the problem provided the node potentials are feasible and a FIFO condition applies to undelayed link travel times. The paper concludes with a numerical example. (C) 2012 Published by Elsevier Ltd
Transferred versus local Safety Performance Functions: A geographical analysis considering two European case studies
No full textTwo main approaches can be used to predict road accidents: transferring existing Safety Performance Functions (SPFs) from other areas (transferred SPFs), and developing local SPFs. Both approaches have advantages and disadvantages, and are affected by the difficult choice of predictors. Regional variables or terrain factors may lead prediction improvements. However, results from previous relevant research are contradictory and transferability assessments are mainly based on North-American experiences.Because of these inconsistencies, this study is an attempt of providing new insights on the choice between alternative accident prediction methods by taking into account the geographic variability in the European context. In particular, it addresses three main issues: 1) it compares the prediction accuracy of transferred and local SPFs; 2) it determines the significance of regional factors in explaining safety performances, 3) it assesses the variability of results among the different contexts considered. Research questions are addressed as based on two-lane rural road sites in Italy and Scotland. The analysis shows differences between the two countries, due to the different nature of the networks, but not within each country. Both advantages and disadvantages were highlighted in the evaluation of transferred and local SPFs. Calibration of transferred SPFs may be less demanding than their local estimation, even if they may lead to unreliable estimates when compared to comprehensive SPFs. However, locally developed SPFs may not provide more significantly reliable estimates than transferred SPFs. Segment curvature and shoulder types are statistically significant predictors in both the Italian and Scottish models, even having different importance
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