This paper is one of two companion papers which survey price elasticities of transport demand. In addition to reviewing empirical elasticity estimates for both freight and passenger demand, this paper also deals with theoretical and empirical issues in estimating transport demand elasticities. The second survey, by Dr. Philip Goodwin, is primarily concerned with empirical estimates of demand elasticities of public traansit system and automobile usage. The origins of motivations of these two papers were different. As was the coverage and sources used. The two papers complemented each other and are therefore published together with a pooled bibliography.

Concepts of price elasticities of transport demand and recent empirical estimates: an interpretative survey. in: urban transport

Multivariate Statistics: A Practical Approach

https://www.tandfonline.com/doi/pdf/10.1080/01441647.2018.1523253

Impacts of automated vehicles on travel behaviour and land use: an international review of modelling studies

The main aim of this study was to use an adapted version of the Unified Theory of Acceptance and Use of Technology (UTAUT) to investigate the factors that influence users’ acceptance of automated road transport systems (ARTS). A questionnaire survey was administered to 315 users of a CityMobil2 ARTS demonstration in the city of Trikala, Greece. Results provide evidence of the usefulness of the UTAUT framework for increasing our understanding of how public acceptance of these automated vehicles might be maximised. Hedonic Motivation, or users’ enjoyment of the system, had a strong impact on Behavioural Intentions to use ARTS in the future, with Performance Expectancy, Social Influence and Facilitating Conditions also having significant effects. The anticipated effect of Effort Expectancy did not emerge from this study, suggesting that the level of effort required is unlikely to be a critical factor in consumers’ decisions about using ARTS. Based on these results, a number of modifications to UTAUT are suggested for future applications in the context of automated transport. It is recommended that designers and developers should consider the above issues when implementing more permanent versions of automated public transport.

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What influences the decision to use automated public transport? Using UTAUT to understand public acceptance of automated road transport systems

This research proposed an eco-driving system for an isolated signalized intersection under partially Connected and Automated Vehicles (CAV) environment. This system prioritizes mobility before improving fuel efficiency and optimizes the entire traffic flow by optimizing speed profiles of the connected and automated vehicles. The optimal control problem was solved using Pontryagin’s Minimum Principle. Simulation-based before and after evaluation of the proposed design was conducted. Fuel consumption benefits range from 2.02% to 58.01%. The CO2 emissions benefits range from 1.97% to 33.26%. Throughput benefits are up to 10.80%. The variations are caused by the market penetration rate of connected and automated vehicles and v/c ratio. No adverse effect is observed. Detailed investigation reveals that benefits are significant as long as there is CAV and they grow with CAV’s market penetration rate (MPR) until they level off at about 40% MPR. This indicates that the proposed eco-driving system can be implemented with a low market penetration rate of connected and automated vehicles and could be implemented in a near future. The investigation also reveals that the proposed eco-driving system is able to smooth out the shock wave caused by signal controls and is robust over the impedance from conventional vehicles and randomness of traffic. The proposed system is fast in computation and has great potential for real-time implementation.

Eco approaching at an isolated signalized intersection under partially connected and automated vehicles environment

The project CityMobil2 has carried out a forward-looking exercise to investigate alternative cybermobility scenarios, including both niche and large-market innovations, and their impacts on European cities and their transport systems. The paper describes the current status of and main trends in automated vehicles, a preliminary vision of the future city with mobility supported mainly by automated vehicles, and freight distribution. The expected positive impacts derive from the development of car sharing, the reduction of space required for parking vehicles, the possibilities for older people or those with disabilities to use cars, the enhancement of safety, and the improvement of efficiency of the transport system.

Automated Vehicles and the Rethinking of Mobility and Cities

The applying of simplified schemes, such as cordon pricing, as second-best solution to the toll network design problem is investigated here in the context of multiclass traffic assignment on multimodal networks. To this end a suitable equilibrium model has been developed, together with an efficient algorithm capable of simulating large scale networks in quite reasonable computer time. This model implements the theoretical framework proposed in a previous work on the toll optimization problem, where the validity of marginal cost pricing for the context at hand is stated. Application of the model to the real case of Rome shows us, not only that on multimodal networks a relevant share (up to 20%) of the maximum improvements in terms of social welfare achievable with marginal cost pricing can in fact be obtained through cordon pricing, but also that in practical terms rationing is a valid alternative to pricing, thus getting around some of the relevant questions (theoretical, technical, social) the latter raises. As a result we propose a practical method to analyze advanced pricing and rationing policies differentiated for user categories, which enables us to compare alternative operative solutions with an upper bound on social welfare based on a solid theoretical background.

Advanced pricing and rationing policies for large scale multimodal networks

The safety level of a pedestrian crossing is affected by infrastructure characteristics and vehicular and pedestrian traffic level. This paper presents a methodology that allows assessing the safety level of a pedestrian crossing, regulated or not by traffic light, in an urban area according to the features of the crossing. A hierarchical structure representing factors influencing crossing safety has been developed and the relative contributions of each factor were calculated using AHP method. A composite index for crossing safety and specific indexes for main aspects included in the assessment have been developed. Main assessment aspects are: Spatial and Temporal Design, Day-time and Night-time Visibility and Accessibility. Night-time Visibility resulted to have the higher weight (about 41%). Developed indexes allow ranking of pedestrian crossings and assigning intervention priorities, highlighting the aspects which are to be enhanced. The methodology has been used for the evaluation of 215 pedestrian crossings in 17 European cities for the Pedestrian Crossing Assessment Project co-financed by FIA Foundation.

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A methodology to assess pedestrian crossing safety

Road Infrastructure Safety Management (RISM) refers to a set of procedures that support a road authority in decision making related to the improvement of safety on a road network. Some of these procedures can be applied to existing infrastructure, thus enabling a reactive approach; and other procedures are used in early stages of a project's life-cycle allowing a proactive approach. The objective of this paper is to provide an overview of the most well-known procedures and present a series of recommendations for successful road infrastructure safety management. The work described in the paper was completed by the IRTAD sub-working group on Road Infrastructure Safety Management and presented in detail in the respective Report. The methodology followed on this purpose included the description of the most consolidated RISM procedures, the analysis of the use of RISM procedures worldwide and the identification of possible weaknesses and barriers to their implementation, the provision of good practice examples and the contribution to the scientific assessment of procedures. Specifically, the following RISM procedures were considered: Road Safety Impact Assessment (RIA), Efficiency Assessment Tools (EAT), Road Safety Audit (RSA), Network Operation (NO), Road Infrastructure Safety Performance Indicators (SPI), Network Safety Ranking (NSR), Road Assessment Programs (RAP), Road Safety Inspection (RSI), High Risk Sites (HRS) and In-depth Investigation. Each procedure was described along with tools and data needed for its implementation as well as relevant common practices worldwide. A synthesis summarizing the key information for each procedure was also drafted. Based on a survey on 23 IRTAD member countries from worldwide, the lack of resources or tools is the most commonly stated reason for not applying a RISM procedure. This has been frequently found mainly in European countries. Another common reason is the absence of recommendations/guidelines, especially for SPI, RAP, RSI and RSA. This highlights the importance of the presence of some legislation regulating the application of the procedures. Lack of data was found important mainly for SPI, HRS and EAT. Good practices of road infrastructure safety management have been explored in order to find solutions to the issues highlighted by the survey and provide examples about how these issues have been overcome in some countries. Specifically, issues related to data, legal framework, funding, knowledge, tools and dealing with more RISM procedures were addressed. Finally, nine key messages and six recommendations for better Road Infrastructure Safety Management were developed based on the conclusions made.

Management of road infrastructure safety

Non-motorized transportation modes, especially cycling and walking, offer numerous benefits, including improvements in the livability of cities, healthy physical activity, efficient urban transportation systems, less traffic congestion, less noise pollution, clean air, less impact on climate change and decreases in the incidence of diseases related to vehicular emissions. Considering the substantial number of short-distance trips, the time consumed in traffic jams, the higher costs for parking vehicles and restrictions in central business districts, many commuters have found that non-motorized modes of transportation serve as viable and economical transport alternatives. Thus, local governments should encourage and stimulate non-motorized modes of transportation. In return, governments must provide safe conditions for these forms of transportation, and motorized vehicle users must respect and coexist with pedestrians and cyclists, which are the most vulnerable users of the transportation system. Although current trends in sustainable transport aim to encourage and stimulate non-motorized modes of transportation that are socially more efficient than motorized transportation, few to no safety policies have been implemented regarding vulnerable road users (VRU), mainly in large urban centers. Due to the spatial nature of the data used in transport-related studies, geospatial technologies provide a powerful analytical method for studying VRU safety frameworks through the use of spatial analysis. In this article, spatial analysis is used to determine the locations of regions that are characterized by a concentration of traffic accidents (black zones) involving VRU (injuries and casualties) in Sao Paulo, Brazil (developing country), and Rome, Italy (developed country). The black zones are investigated to obtain spatial patterns that can cause multiple accidents. A method based on kernel density estimation (KDE) is used to compare the two cities and show economic, social, cultural, demographic and geographic differences and/or similarities and how these factors are linked to the locations of VRU traffic accidents. Multivariate regression analyses (ordinary least squares (OLS) models and spatial regression models) are performed to investigate spatial correlations, to understand the dynamics of VRU road accidents in Sao Paulo and Rome and to detect factors (variables) that contribute to the occurrences of these events, such as the presence of trip generator hubs (TGH), the number of generated urban trips and demographic data. The adopted methodology presents satisfactory results for identifying and delimiting black spots and establishing a link between VRU traffic accident rates and TGH (hospitals, universities and retail shopping centers) and demographic and transport-related data.

Luca Persia

Papers

Automated Vehicles and the Rethinking of Mobility and Cities

Advanced pricing and rationing policies for large scale multimodal networks

A methodology to assess pedestrian crossing safety

Management of road infrastructure safety

Characterization of Black Spot Zones for Vulnerable Road Users in São Paulo (Brazil) and Rome (Italy)