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Causes And ConseqUences of Low Urban accessibility. Defining proper policy responses

Periodic Reporting for period 1 - CAlCULUS (Causes And ConseqUences of Low Urban accessibility. Defining proper policy responses)

Reporting period: 2017-09-01 to 2019-08-31

The CAlCULUS project aimed to explore reasons for limited accessibility, in particular, in urban areas. The main goal was to improve our understanding of how to take advantage of new data sources in order to improve transport planning and management in modern smart cities. Accessibility has become a key issue for achieving sustainable development, improvement of quality of life, reduction of transport-related air and noise pollution as well as a decrease in social and spatial inequalities. It is also among the global challenges addressed by the Sustainable Development Goals which frame the current United Nations and European agendas. Proper identification of causes of unfavourable accessibility patterns should facilitate the formulation of more efficient policy responses in order to improve the level of accessibility, diminish its inequalities and improve quality of life of inhabitants. The main project rationale was that despite the growing body of transport accessibility literature, most of the studies focused on consequences of particular spatial patterns of accessibility, leaving aside the causes that led to accessibility shortfalls in urban areas. The original approach of the project applied temporal dynamics of transport networks in order to uncover the underlying mechanisms leading to an unfavourable accessibility pattern.
The main research activities of the CAlCULUS project were related to accessibility analysis. For that reason, a comprehensive database was needed, covering route network and public transport data, distribution of population and potential destinations (e.g. job location or public services), among others. The collected private transport network data contained speed profiles, which enabled to analyse how accessibility evolves in time. The acquired data covers Spain and Poland. For the purpose of analyses of accessibility by public transport, detailed schedule-based data (so-called GTFS feeds – General Transport Feed Specification) were collected for more than twenty European cities. All GTFS datasets were supplemented by pedestrian networks, as well as population and job distribution data in fine spatial resolution.
Accessibility analyses conducted in CAlCULUS project covered three main topics:
The first one focused on assessing the impact of temporal resolution on the precision of public transport accessibility measurement. The research used the medium-size Polish city of Szczecin as a case study and included an evaluation of the impact of four sampling methods, four different public transport frequency scenarios, three types of accessibility measures (travel time to the nearest provider, cumulative opportunities measure and potential accessibility) and seven types of destinations ranging from high to low centrality of their spatial distribution. The study, conducted in international collaboration, was summarized in the paper published in the Journal of Transport Geography (2019).
The second branch of accessibility analysis took advantage of time-sensitive transport networks in order to delineate areas of low urban accessibility and to identify main transport-related accessibility restrictions in given areas. The novel approach enabled the preparation of several scenarios of accessibility levels in order to compare them against each other to assess the impact of particular factors on a decrease of accessibility level. These scenarios included trips made by private cars as well as public transport (an assessment of intermodal imbalance of accessibility), with the application of congested or free-flow speeds (an impact of congestion), trips made during peak and off-peak hours (an impact of frequency of public transport service) and, in the case of trips made by public transport, with and without waiting times (which permits evaluating the impact of public transport network design).
The third topic related to accessibility analysis aimed to evaluate the supply side of public transport at the European level, using open data (mostly GTFS) and open source solutions. The developed approach enables for straightforward evaluation of public transport service in a given area and easy comparison of results between different cities or functional urban areas (FUA), including international comparisons. Additionally, the CAlCULUS project aimed to investigate the interrelation between accessibility and mobility looking at the extent to which an increased mobility reinforced congestion and negatively influenced on accessibility to jobs.
The communication activities concentrated on the dissemination of the project results to professionals and the scientific community. The results of the CAlCULUS project were presented and discussed at several scientific conferences and workshops. Additionally, the general public was reached during the European Researchers’ Night events in Madrid, which was a perfect opportunity to attract a wider audience and raise their attention to transport planning and the importance of accessibility analysis, in particular in urban areas.
The CAlCULUS project has made an important contribution to the way we measure accessibility and how we can use the results of accessibility analysis. The main project contributions cover three aspects:
First, the project extensively investigated the extent to which results of accessibility analyses by public transport might be distorted by the application of a particular temporal resolution. The main findings show that temporal resolution indeed influences the precision of accessibility analyses, however, the impact is reduced and depends on several factors, including frequency of public transport service, accessibility measure applied, or distribution of destinations. The results suggest that the application of 15-min temporal resolution provides a good balance between computational time and precision of travel time and accessibility measurement, while an increase of temporal resolution up to 5 minutes offers almost negligible loss of precision associated with a significantly reduced computational time.
Second, the project results demonstrate the power of applying time-sensitive transport network data. The temporal variability of accessibility level and the inter-modal imbalance were proposed as diagnostic methods in order to identify transport-related accessibility restrictions. Thus, the proposed approach can be used as a support tool for transport planning decisions in order to tackle the problem of limited accessibility in urban areas.
Third, the international collaboration settled by CAlCULUS project prepared an extensive, comparative research of public transport services. The study is based exclusively on open source solutions fed by open data (OpenStreetMap and GTFS data for public transport analysis, and Eurostat’s GEOSTAT data on population distribution). The proposed method facilitates a comparison of supply of public transport services between cities and a monitoring of changes in the course of time.
Congestion vs public transport alternative
Accessibility scenarios in CAlCULUS project
Speed profiles