An assessment method for highway network vulnerability

This paper introduces a methodology to assess the level of vulnerability of road transport networks. A new technique based on fuzzy logic and exhaustive search optimisation is used to combine vulnerability attributes with different weights into a single vulnerability index for network links, which may be used to measure the impact of disruptive events. The network vulnerability index is then calculated using two different aggregations: an aggregated vulnerability index based on physical characteristics and an aggregated vulnerability index based on operational characteristics. The former uses link physical properties such as its length and number of lanes, whilst the latter reflects aspects of the network flow. The application of the methodology on a synthetic network (based on Delft city, Netherlands) demonstrates the ability of the technique to estimate variation in the level of vulnerability under different scenarios. The method also allows exploration of how variation in demand and supply impact on overall network vulnerability, providing a new tool for decision makers to understand the dynamic nature of vulnerability under various events. The method could also be used as an evaluation tool to gauge the impact of particular policies on the level of vulnerability for the highway network and highlight weaknesses in the network.     

Analysing the spatial-temporal characteristics of bus travel demand using the heat map

As the basic travel service for urban transit, bus services carry the majority of urban passengers. The characterisation of urban residents' transit trips can provide a first-hand reference for the evaluation, management and planning of public transport. Over the past two decades, data from smart cards have become a new source of travel survey data, providing more comprehensive spatial-temporal information about urban public transport trips. In this paper, a multi-step methodology for mining smart card data is developed to analyse the spatial-temporal characteristics of bus travel demand. Using the bus network in Guangzhou, China, as a case study, a smart card dataset is first processed to quantitatively estimate the travel demand at the bus stop level. The term ‘bus service coverage’ is introduced to map the bus travel demand from bus stops to regions. This dataset is used to create heat maps that visualise the regional distribution of bus travel demand. To identify the distribution patterns of bus travel demand, two-dimensional principal component analysis and principal component analysis are applied to extract the features of the heat maps, and the Gaussian mixture model is used for the feature clustering. The proposed methodology visually reveals the spatial-temporal patterns of bus travel demand and provides a practical set of visual analytics for transit trip characterisation.     

The path and time efficiency of residents' trips of different purposes with different travel modes: An empirical study in Guangzhou,China

Improving residents' travel efficiency and reducing carbon emissions from travel are the key issues for sustainable development of urban transportation. This study first employed a circuity index to measure the path efficiency of residents' trips based on 2015 survey data in Guangzhou and developed a generalized additive model (GAM) to investigate the relationship between the path efficiency and travel distance for different purposes of trip and different travel modes. On this basis, it further evaluated the time efficiency of different travel modes for each trip. The results showed that there is a complex and nonlinear relationship between the path efficiency and travel distance, which differs between different purposes of trips and different travel modes. In general, trips by non-motorized transport have a lower circuity index and higher path efficiency than those by cars or public transport. Moreover, non-motorized transport is the time-efficiency optimal mode for almost half of the trips, especially for daily shopping trips. However, people prefer to choose public transport on their trips even though public transport is not the time-efficiency optimal mode for these trips. Generally, only about half of the residents chose the time-efficiency optimal mode for their trips. Those who did not choose the time-efficiency optimal mode tended to choose the modes with higher carbon-intensity. The conclusions of this study indicate that for improving travel efficiency and reducing carbon emissions from transport, more efforts should be focused on the non-motorized travel environment and developing relevant policies to encourage more walking and cycling.     

Public transport accessibility in metropolitan areas: A new approach incorporating population density

Improving public transport accessibility can be considered an effective way of reducing the external costs and negative side effects of motorized commuting. Although there have been many studies conducted that have measured access levels to public transport stops/stations, there has been limited research on measuring accessibility that integrates population density within geographical areas. This study develops a new measure that considers public transport service frequency and population density as an important distributional indicator. A public transport accessibility index (PTAI) is formulated for quantifying accessibility within local areas in metropolitan Melbourne, Australia. A public transport network model is applied to identify the service coverage of public transport modes using a Geographical Information System (GIS). A consistent method is introduced for evaluating public transport accessibility for different levels of analysis, from single elements, including public mode stops to network analysis. The Victorian Integrated Survey of Travel and Activity (VISTA) is used to evaluate the index and examine the association between commuting trips undertaken by public transport and the level of accessibility within the Melbourne metropolitan region. Furthermore, the new index is compared with two existing approaches using the VISTA dataset. Key findings indicate that the PTAI had a stronger association whilst showing more use of public transport in areas with higher values of the PTAI.     

Selecting tram links for priority treatments - The Lorenz Curve approach

Road and public transport authorities often have a difficult task in deciding which road links to select for investment in preferential traffic and public transport measures to improve public transport service performance. This paper presents a new approach which adopts the economic concept of the Lorenz Curve to compare link performance in terms of transit operations as well as weighted passenger volume of travel. The paper explores if, and how, these metrics can be re-interpreted to help with targeting improvements for on-road public transport and priority mitigations. The approach collates operational performance data, in this case link speed and also link public transport travel volume to plot the cumulative distribution of link speed/ridership performance as a curve. Two sets of test applications are presented; on a route level basis and secondly a network level analysis. The network level results present the most powerful results with the Lorenz Curve analysis able to quickly identify links that justify greater attention for preferential treatments since they have the worst 20th percentile of operational performance but the highest 40th percentile of relative link ridership. Mapping shows the problem links to be busy routes leading into the central city. Implications for wider application of these methods are discussed.     

Evaluating the value of new metro lines using route diversity measures: The case of Hong Kong's Mass Transit Railway system

The Mass Transit Railway (MTR) serves as the backbone of the Hong Kong public transportation network and continues to be expanded in phases. Nevertheless, occasional but severe disruptions have raised concerns about whether the proposed MTR expansions will benefit the system resilience. To assess the value of each stage of MTR network expansion, it is key to identify the distributive effects of new metro lines on both accessibility and resilience. This paper applies the route diversity index, a relatively new accessibility indicator, to assess the effects of new lines and evaluate their spatial distribution, variation, and changes at nodal, dyadic, and network levels. The results indicate that the effects on accessibility and resilience will differ between each stage of MTR expansion. On the accessibility front, the benefits of reduced travel times and increased route diversity will be successively extended to more districts with each MTR expansion, and the spatial equity will also be improved gradually by the expansion, especially in isolated regions such as the northern and western New Territories. In contrast, on the resilience front, although the overall network vulnerability will be reduced, the vulnerability of certain parts of the network will be increased, which might necessitate additional resources to protect these stations. However, some new lines will reduce this vulnerability and provide a complementary solution to enhance network resilience. Overall, the insights from this study could assist in cost-effective resource allocation and informed decision-making for the prioritization of future railway investments and cost-effective resource allocation.     

Modelling growth principles of metropolitan public transport networks

The development of metropolitan public transport networks often involves choosing between investing in extending radial lines or constructing ring connections. While the former enlarges network coverage the latter enhances network connectivity and reduces the need to perform detours. Moreover, investments might be better directed at increasing the capacity of already existing infrastructure. In this study we address the following question: how do transport networks in metropolitan areas evolve over time and how can we effectively model this growth as function of demand and cost function? The goal of this study is to determine the fundamental relations between population distribution, modal costs on the prevailing network structure and its evolution. The approach taken in this study offers a theoretical contribution to the field of transport network growth by combining principles from several research streams: transport geography, economics of network growth and network science. We propose an iterative investment model network analysis framework. The results of the network growth experiments manifest an overall trend in network growth with an early phase of expansion of the network, followed by a period of intensification manifested in capacity increments and finally adding some links that contribute to its densification. Furthermore, our findings suggest that bus networks include more ring-radial connections than Light Rail Train and Metro networks which are more concentrated on radial connections.     

Examining the spatial–temporal dynamics of bus passenger travel behaviour using smart card data and the flow-comap

Over the past two decades, smart card data have received increasing interest from transport researchers as a new source of data for travel behaviour investigation. Collected by smart card systems, smart card data surpass traditional travel survey data in providing more comprehensive spatial–temporal information about urban public transport-based (UPT) trips. However, the utility of smart card data has arguably yet to be exploited fully in terms of extracting and exploring the spatial–temporal dynamics of UPT passenger travel behaviour. To advance previous work in this area, this paper demonstrates a multi-step methodology in order to render more insightful spatial–temporal patterns of UPT passenger travel behaviour. Drawing on the Brisbane, Australia, bus network as the case study, a smart card dataset was first processed in combination with General Transit Specification Feed (GTFS) data to reconstruct travel trajectories of bus passengers at bus stop level of spatial granularity. By applying geographical information system-based (GIS) techniques, this dataset was used to create flow-comaps to visualise the aggregate flow patterns at a network level. The flow-comaps uncovered the major pathways of bus passengers and its variations over a one-day period. The differences within the flow-comaps were also quantified to produce weighted flow-comaps that highlighted the major temporal changes of passenger flow patterns along a number of stop-to-stop linkages of the bus network. The proposed methodology visually unveiled the spatial–temporal travel behaviour dynamics of UPT passengers and, in doing so, showed the potential to contribute to a new evidence base with the capacity to inform local public transport policy.     

Predictive spatial network analysis for high-resolution transport modeling,applied to cyclist flows,mode choice,and targeting investment

Betweenness is a measure long used in spatial network analysis (SpNA) to predict flows of pedestrians and vehicles, and more recently in public health research. We improve on this approach with a methodology for combining multiple betweenness computations using cross-validated ridge regression to create wide-scale, high-resolution transport models. This enables computationally efficient calibration of distance decay, agglomeration effects, and multiple trip purposes. Together with minimization of the Geoffrey E. Havers (GEH) statistic commonly used to evaluate transport models, this bridges a gap between SpNA and mainstream transport modeling practice. The methodology is demonstrated using models of bicycle transport, where the higher resolution of the SpNA models compared to mainstream (four-step) models is of particular use. Additional models are developed incorporating heterogeneous user preferences (cyclist aversion to motor traffic). Based on network shape and flow data alone the best model gives reasonable correlation against cyclist flows on individual links, weighted to optimize GEH (r² = 0.78, GEH = 1.9). As SpNA models use a single step rather than four, and can be based on flow data alone rather than demographics and surveys, the cost of calibration is lower, ensuring suitability for small-scale infrastructure projects as well as large-scale studies.     

Policies to attract drivers out of their cars for short trips

This paper examines the policies and personal actions that might attract motorists out of their cars onto the alternatives for short trips. The analysis is based on the results of surveys carried out on a project for the UK Department of the Environment, Transport and the Regions. The various events that car drivers say could attract them to an alternative are examined. The actions associated with each of the alternatives to the car are identified. According to the respondents, the most significant action to reduce the number of car trips would be to improve public transport. The potential impact of the implementation of all the actions identified on the number of short car trips nationally is calculated.     

Multi-modal network evolution in polycentric regions

The development of public transport networks in polycentric regions involves making complex trade-offs between extending network coverage, densifying local connections, offering improved connections between urban centers and increasing capacity on existing links. Moreover, different modalities might be suitable for each of these development decisions depending on their speed, capacity and cost function structure. The objective of this study is to identify the influence of polycentric configurations and their respective travel demand distributions on the emerging topology of the corresponding multi-modal public transport network using an iterative growth model. Since polycentricity comes in many forms, our experimental design considers four polycentric configurations inspired by the cases of London, Tokyo, the Flemish Diamond and the Rhine-Ruhr area.The results are analysed in terms of both the properties of the obtained network structure as well as the evolutionary path and the sensitivity of both to key model settings and design variables. We find that more uneven population distributions result with the construction of fewer links and consequently the less connected and shorter the network becomes. The network evolutionary path is marked by distinctive intra- and inter- agglomeration expansion, densification and bulking phases. While the costs associated with each investment are the same regardless of the moment at which the investment is made, the benefits are not. This path dependency means that the evolutionary path is characterized by the need to attain a critical mass to justify further developments.     

Land use and public transport integration in small cities and towns: Assessment methodology and application

It is widely accepted that land use and public transport planning should be harmonised in order to provide a viable alternative to car transport. Following the Transit-Oriented Development (TOD) concept, many studies and plans aim to concentrate urban development in areas accessible by high-quality public transport. Encouraged by studies asserting the positive relation between urban density and public transport use, scholars and practitioners focused their attention on tools and strategies that increase urban density, thereby overlooking geographical contexts where these strategies cannot be applied. TOD might however be also a valuable strategy in low-density contexts, like lower density parts of metropolitan areas, or suburban areas and small towns. It seems therefore relevant and interesting to develop a methodology to explore the value of TOD strategies in such contexts. Our paper fills this analytical and application gap and proposes to extend the conceptualization and implementation of land use and public transport integration to areas where low-density urban development has already occurred (e.g., low-density suburbs, or areas where the protection of natural and cultural heritage precedes urban development). In such cases, where is not possible to increase urban density around transport nodes, the quality of the transport network plays a decisive role.The approach builds on the Node-Place Model by including evaluations of the quality of feeder networks. We applied the methodology to a case study in the Campania Region in southern Italy, indicating a possible way to evaluate land use and public transport integration while considering, at the same time, the quality of transport as network.The application of the methodology allowed to highlight imbalances between accessibility – by main and feeder transport – and land use intensity, and to sketch urban development strategies and priorities of intervention on the transport network.     

Distributional effects of public transport subsidies

We analyze the distribution of transit subsidies across population groups in Stockholm. We develop a novel methodology that takes into account that the subsidy per passenger varies across transit links, since production costs and load factors vary. With this, we calculate the subsidy per trip in the transit network and analyze the distribution of subsidies across population groups. The average subsidy rate in Stockholm is 44%, but the variation across trips turns out to be large: while 34% of the trips are not subsidized at all but generates a profit, 16% of the trips have a subsidy rate higher than 2/3. We calculate the concentration index to explore the distribution of subsidies across income groups. The average subsidy per person is similar for all income groups, except for the top income quintile. This holds not only for the current flat-fare system, but also for distance-based fares and fares with a constant subsidy rate. Transit subsidies is hence not effective as a redistribution policy in Stockholm. The largest systematic variation we find is across residential areas: the average subsidy per person is five times higher in the peripheral areas of the region compared to the regional core, and the subsidy per trip is ten times higher.     

Exploring the impact of public transport strikes on travel behavior and traffic congestion

Public transport (PT) disruption can occur due to various factors such as malfunctions and breakdowns of vehicles, power outages, and personnel strikes. This paper explores the network-wide impacts of PT strikes (train, tram, and bus strikes) on traffic congestion in Melbourne, Australia using a network modeling approach. A primary survey aimed to investigate the mode shift of users when each public transport mode ceases was conducted with 648 public transport users in May 2016. Findings show that train withdrawal was expected to result in 43% of users shifting to car. Smaller yet significant shifts to car was also expected with bus withdrawal (34%) and tram withdrawal (17%). Based on the survey results and the use of a four-step transport model, train withdrawal was expected to increase the number of severely congested road links by 130% and reduce the average travel speed from 48 km/h to 39 km/h (20% decrease). Bus and tram withdrawal was also found to increase congestion although the result was less severe. Future research should investigate the switching behavior in actual withdrawal events and explore the long-term effects of public transport withdrawal.     

Improving Bus Service Levels and social equity through bus frequency modelling

Bus lines play an essential role in providing urban public transport service. Demographic and socioeconomic characteristics determine the specific transport service needs of districts that, in most cases, are not served by the existing bus routes. Small changes in the frequency of a bus route can have a direct effect on the territorial distribution of a city's public transport service. Adjusting the frequencies of a bus fleet can help planners improve the service level and adapt the fleet's spatial distribution. A bus frequency optimization methodology is proposed to improve harmonization between service level and social equity in public transport. The method relies on a simple spreadsheet that integrates geographic data about bus routes and socioeconomic information about city districts. Simulation and optimization procedures are coordinated to appropriately adjust the routes to the geographic space. The proposed method is tested in a real case study that demonstrates its usefulness in analysing the service level and equity of a transport system and improving a city's public transport planning.     

Ports in multi-level maritime networks: evidence from the Atlantic (1996–2006)

While maritime transport ensures about 90% of world trade volumes, it has not yet attracted as much attention as other transport systems from a graph perspective. As a result, the relative situation and the evolution of seaports within maritime networks are not well understood. This paper wishes verifying to what extent the hub-and-spoke strategies of ports and ocean carriers have modified the structure of a maritime network, based on the Atlantic case. We apply graph measures and clustering methods on liner movements in 1996 and 2006. The methodology also underlines which ports are increasing their position by carriers’ circulation patterns on various scales. This research demonstrates that the polarization of the Atlantic network by few dominant ports occurs in parallel with the increased spatial integration of this area by shipping lines.     

Examining commuting patterns using Floating Car Data and circular statistics: Exploring the use of new methods and visualizations to study travel times

In this paper, we focus on the spatial distribution of travel time differences between car and public transport during peak and off-peak hours using geospatial methods and circular statistics. To that end, we combine two origin-destination matrices: one contains the number of simulated commuting trips and the other contains accurate travel times measured using either Floating Car Data or transit data. The combination of both matrices reveals that differences in travel time during peak and off-peak hours are high for intra-city commuting and low for inter-city commuting.     

The impacts of the built environment on bicycle-metro transfer trips: A new method to delineate metro catchment area based on people's actual cycling space

Bicycle-metro integration is an efficient method of solving the “last mile” issue around metro stations. Built environment is believed to have a significant effect on cycling behavior. However, transfer cycling around metro stations, as a specific type of cycling behavior, has often been overlooked in transport research. In addition, static contextual units such as circular or street-network buffers are typically used to delineate metro catchment areas of transfer cycling trips. These methods are inaccurate to represent the actual geographic contexts of cycling trips, according to the uncertain geographic context problem (UGCoP). Thus, in this study, bicycle-metro catchment areas are delineated based on aggregating the end points of over three million transfer cycling trips. The impact of the built environment on transfer cycling behavior is also explored.First, we find that the aggregate-points buffer outperforms traditional static buffers in predicting transfer cycling trips. Second, we also identify a high level of spatial heterogeneity in catchment area and transfer cycling density between urban and suburban areas. Third, residential and working population density, bus stop density, and metro stations accessibility have a significant effect on bicycle-metro transfer cycling.     

Spatial and socio-economic analysis of public transport systems in large cities: A case study for Belo Horizonte,Brazil

The main goal of this article is to evaluate the relationship between the spatial distribution of the population of the city of Belo Horizonte, one of the largest cities in South America, and its public transport network, seeking to ascertain whether the current bus network is able to meet the needs of the population. The methodology was based on data processing and vector information from different sources through spatial analysis tools. As expected, the results revealed a greater concentration of routes and bus stops in the central region of Belo Horizonte, which is the main commercial center of the municipality and its metropolitan region. However, the results suggest evidences of a disadvantage for the population with lower income, especially those living on the periphery. A possible explanation for this disadvantage is the invisibility of these communities due to their high level of irregular occupation. Under the eyes of public transport planning, they are not recognized, and, theoretically, do not generate demand for lines and bus stops     

Longitudinal macro-analysis of car-use changes resulting from a TOD-type project: The case of Metro do Porto (Portugal)

Transit-oriented development has been widely studied in recent years as a means to reduce car trips and promote sustainable transport modes. However, longitudinal studies on the matter are still rare. This paper contributes to longitudinal research of Transit-Oriented Development (TOD) effects on travel behavior by analyzing the evolution of the number of car trips after the implementation of a light-rail metro system in the Porto region (Portugal). As Metro do Porto is a large infrastructure project (a metro network of 67 km), we relied on a macro-analysis performed at the civil parish level. Changes in the number of car trips are evaluated using a difference-in-differences model, extended to a spatial model to account for the metro's spillover effects. These effects became obvious as metro ridership is reported not only in the directly metro-served parishes but also in adjacent non-served parishes. The results highlight the importance of the metro system in reducing the number of car trips, and this effect is visible not only in metro-served parishes but also in the neighboring ones, which are not directly served by the new transport system. Furthermore, we compare the performance of parishes predominantly served with TOD stations to those with transit-adjacent (TAD) and park-and-ride (P&R) stations. We conclude that both station types can reduce the number of car trips, yet only TOD parishes generated significant spillover effects. The importance of other potentially influential factors like building density or socio-economic characteristics is also discussed.