Urban mobility SCIENCE & RESEARCH International Transportation (71) 1 | 2019 39 Significance map pedestrian traffic Leipzig Mapping the relevance of the built environment for pedestrian traffic as the basis for strategic network development Pedestrian traffic, Walking, Network planning, Urban street design, Points of Interest, Geodata This paper presents the methodology for developing a significance map for pedestrian traffic using the city of Leipzig as an example. Based on assumptions about the relevance and catchment areas of origins and destinations for pedestrian traffic, significance levels are assigned to public spaces. These represent the potential for pedestrian traffic that can be expected from the urban structures in the vicinity of the respective public spaces. The significance map created in this way allows for hierarchization of pedestrian networks and prioritization of measures promoting pedestrian traffic. Friedemann Goerl, Frederik Sander, Robert Guschel, Caroline Koszowski, Regine Gerike P edestrian traffic, both as movement between origins and destinations (walking) and as lingering in public spaces (place activities), is associated with many benefits. Spending time in public spaces is an essential quality of urban life and the liveliness of public spaces promotes the economic success of adjacent businesses as well as social security. Economically, ecologically and in terms of land consumption, walking is the most efficient way of getting around and it is a necessary part of most trips as a means of getting to and from motorized transport and in particular local public transport (LPT). Walking as a physical activity also directly contributes to the promotion of public health. These multiple positive effects of walking and place activities, which together materialize in the streets as pedestrian traffic, are increasingly being recognized, and many stakeholders show high commitment to its promotion from the strategic level of walking concepts [1, 2] to the design of attractive and safe street spaces [3]. This high significance of pedestrian traffic at the interface between urban, transport Leipzig, town square Photo: Falco / pixabay Urban mobility SCIENCE & RESEARCH SCIENCE & RESEARCH Urban mobility International Transportation (71) 1 | 2019 40 and health planning is clearly at odds with the inadequate data situation. Street-level data on pedestrian volumes have traditionally been scarcely collected, primarily for reasons of costs and planning priorities: The recording of pedestrian volumes is timeconsuming because it has mainly been done manually; automatic counting stations are hardly used and show considerable inaccuracies [4]. In addition, the focus of studies and planning has so far often been on motorized traffic (individual and public), increasingly also on cycling but less on walking. Technological innovations offer promising opportunities to improve the data situation, e. g. on the basis of data collection with video cameras or other imaging technologies with increasingly automated extraction of pedestrian volumes and trajectories. However, these new technologies have so far only been applied selectively. The visibility of pedestrian traffic in mobility surveys is limited by the principle of the main mode of transport. Common modal split evaluations are based on the distribution of trips in the population across the different modes of transport but do not consider the individual segments of each trip. Typical walking shares in these evaluations are about 30 percent which only includes those trips which are entirely completed on foot. The walking done as a part of other trips, especially when LPT is used, is not visible [1]. In terms of relevant influencing factors, the “5 Ds” (Density, Diversity, Design, Distance to Public Transport (PT), Destination Accessibility) are the most widely used system in the international literature to classify spatial determinants of pedestrian volumes [2]. Density is usually operationalized as population density or proportion of built-up area to total area (“floor area ratio”) within a given radius of a street segment [3]. The diversity of land use is described in terms of measures of entropy or, more simply, proportions of particular uses [4]. Density and diversity are the two most important variables for explaining pedestrian volumes; they are consistently significant and show the highest effect sizes. Shorter distances to PT stops also increase walking volumes. Design variables at the network level are significant only in some studies and are operationalized, for example, by the density of network nodes per area or block sizes [4]. In recent studies, the network indicator “betweenness centrality” shows significant relationships with pedestrian volumes derived from the centrality of nodes and edges in a network [5]. Accessibility of local destinations such as supermarkets shows significant interactions with land use diversity and has less of an impact on pedestrian volumes [2]. The radius of street segments studied varies from 250 m to 800 m, with different radii often applied to different destinations (e.g., PT stops or supermarkets) [6]. These findings on the determinants of pedestrian traffic can be used to estimate the importance of streets and public spaces for pedestrian traffic based on built environment data, allowing for hierarchization of networks and prioritization of planning without having empirical data available. This paper presents such an approach using the city of Leipzig as an example. Based on assumptions about the relevance and range of origins and destinations (points of interest, POIs) as well as land uses (e. g. parks) for pedestrian traffic, each element of the public space is assigned a level of significance. These represent the pedestrian traffic potential that can be expected for the urban structures present in the vicinity of each space based on the findings generated in the literature. The method thus implicitly estimates pedestrian volumes. However, due to the lack of validation with actual numbers so far, the new method remains on the qualitative level of assigning potentials and does not claim to estimate pedestrian volumes quantitatively. However, it already allows for comparisons to be made between different urban areas and their importance for pedestrian traffic. Case study for the city of Leipzig With its dense urban structures, wide boulevards, and an attractive city center with few cars, the city of Leipzig offers very good conditions for pedestrians and committed itself early on to promoting this mode of transport. The Concept for Pedestrian Traffic in Leipzig, which was adopted in 1997, already committed itself to the goals of becoming a city of short distances to destinations and the strengthening of pedestrian traffic. This high priority is also visible in the strategic planning documents and activities that followed. These are, above all, the Urban Development Plan for Transport and Public Space from 2015, the creation of the position of a pedestrian traffic officer as the first city in Germany in 2018, and the Mobility Strategy 2030 in 2018 [1]. For the ongoing systematic promotion of pedestrian traffic, a threestage approach is envisaged with the following components: a) the pedestrian strategy as a conceptual basis, b) the pedestrian development plan for identifying networks and focal points for measures at the citywide level, and c) integrated local transport concepts at the district level, which also include pedestrian traffic. The demand-side goals formulated in the pedestrian strategy adopted in 2021 focus on the modal split share of pedestrian traffic, which is to be stabilized. Supply-side goals relate to the identification of networks, the development of attractive, accessible, and safe infrastructure, the strengthening of pedestrian-friendly mobility cultures, and the implementation of schemes for monitoring and evaluation. The significance map to be presented below works toward several of these goals (Figure-1). It enables, among other things, the evidencebased identification of citywide development priorities as a basis for network development, the prioritization of measures for the redesign or rehabilitation of street Figure 1: Significance map pedestrian traffic of the city of Leipzig Source: Authors Urban mobility SCIENCE & RESEARCH International Transportation (71) 1 | 2019 41 spaces, as well as traffic monitoring and public transport network planning. Methodology for the development of the significance map The literature summarized above shows that pedestrian traffic, in contrast to other modes of transport, has a particularly strong relationship with the surrounding built environment and urban structures. Origin and destination relationships along routes and axes over long distances are much less relevant than the direct surroundings with the respective urban development options and local situation. Given this background, the methodology for the creation of the significance map for the city of Leipzig is based on the assumption that specific pedestrian-relevant and -generating locations in roadside spaces as points of interest (POIs) as well as land uses such as green spaces each generate typical pedestrian volumes with typical ranges. The selection of POIs and land uses is based on the facilities with increased Group Type Data source Data type Influence area Significance Residence population focal points City raster area of the raster 1 -10 population *0,02 nursing homes City POI 500m 7 Educational facilities kindergartens City POI 200m 7 elementary schools City POI 200m 7 secondary schools City POI 200m 7 universities City/ OSM POI 400m 7 Services, retail and gastronomy stores OSM POI 200m 1 large-scale retail trade OSM, self collected POI 300m 10 gastronomy OSM POI 300m 2 Public buildings public administration and citizen offices City POI 300m 6 libraries & post offices City/ OSM POI 300m 6 police & judiciary OSM POI 300m 3 Places of assembly, sports & recreation sports facilities City/ OSM POI 200m 2 playgrounds OSM POI 200m 4 public pools City POI 200m 6 major events self collected POI 500m 20 hotels, guesthouses OSM POI 300m 3 museums, buildings of major importance City/ OSM POI 200m 6 Public transport stops bus stops City POI 300m 10 streetcar stops City POI 300m 15 local rail passenger transport stops City/ self collected POI 500m 20 Health hospitals self collected POI 500m 20 medical practices, health care supplies, social services City/ OSM POI 300m 3 Green, blue and square spaces cemetery City polygons area 10 forest/ woods City polygons area 10 community gardens City polygons area 5 squares City polygons area 10 bodies of water City polygons area + 100m 15 park/ landscaped green space City polygons area + 100m 20 Historic town centers on the outskirts of the city town centers historic maps Meilenblätter Sachsen, Berliner Exemplar polygons area 15 100m buffer around town centers historic maps Meilenblätter Sachsen, Berliner Exemplar polygons area 5 Tracking data no to low frequency Strava Metro Line + 20m buffer area 0 low frequency Strava Metro Line + 20m buffer area 10 medium frequency Strava Metro Line + 20m buffer area 50 high frequency Strava Metro Line + 20m buffer area 100 very high fequency Strava Metro Lnie + 20m buffer area 150 Table 1: Grouping of the Points of Interest (POIs) and land uses including influence areas and significance levels SCIENCE & RESEARCH Urban mobility International Transportation (71) 1 | 2019 42 requirements for sidewalks listed in the Recommendations for Pedestrian Facilities (EFA) of the FGSV [7], which are adapted in typification and ranges based on the literature in combination with plausibility checks on site and considerations beyond that (Table- 1). Population focal points are incorporated as 100 m x 100 m grid data; educational institutions, services, public buildings, assembly/ sports and recreational facilities are more differentiated compared to the EFA [7]; for LPT, a distinction is made between bus, streetcar and SPNV (local rail passenger transport) stops and the ranges are adjusted in accordance with the local transport plan; a separate group for green, blue and open spaces is added to reflect their importance for pedestrian traffic. In addition to the range, each type of POI is assigned a significance, which in aggregation is equivalent to a weighting of the different types. The determination of the significance is carried out taking into account findings from the literature on the pedestrian traffic potential of certain types of POIs, expert knowledge and political votes on the prioritization of selected user groups such as children and senior citizens, with a range of one to 20 for the significance levels. Municipal policy committees, the expert public in the form of the Urban Working Group for the Promotion of Pedestrian Traffic and the Round Table for Pedestrian Traffic, as well as the city district advisory councils and local councils were intensively involved in the development of the significance map. For the classification of the significance of the population focal points, the persons registered in the 100 m × 100 m grid are multiplied by a coefficient of 0.02, thus generating a range from one to ten. This weighting has also been evaluated and adjusted several times within the administration and through the Working Group for the Promotion of Pedestrian Traffic in terms of its impact on the overall result. LPT stops are assigned a basic value according to table 1. In-addition, transfer stops are given five further points of importance, which are further increased in the case of shorter service intervals based on the local transport plan of the city of Leipzig [8]. In order to achieve a differentiated balance between inner-city and suburban locations, historic local subcenters in the Leipzig urban area were identified and their significance increased. Former sub-centers on the outskirts of the city of Leipzig are thus included in the evaluation as special cases with 10 points. To determine the significance for parks, tracking data from the company Strava is used to estimate pedestrian traffic that is independent of POIs. Since the tracking data particularly depicts recreational pedestrian traffic ( jogging, going for a walk), it allows for a more detailed analysis of the relevance of green spaces for pedestrian traffic. Spaces in green areas with a particularly high frequency receive up to 150 points, in order to establish a comparability to street spaces. This allows for adequate consideration of these land uses that are important for pedestrian traffic, including recreational travel that is less oriented to POIs. To determine the overall significance of a street segment across all POIs and land uses taken into account, a network analysis is performed around each POI which contributes to the overall significance with the respective range. No circles are drawn around POIs, but differentiated routing is performed along the actual street and the path network. The significance of the influence areas overlaying each street segment are weighted and added together to determine the overall significance for each street segment. The analysis is built on a route network which is based on two data sets. These are on the one hand the route network from OpenStreetMap (OSM) as lines and on the other hand traffic zones as polygons from the city of Leipzig. While the traffic zones only include those areas that are in the property of the Transport and Civil Engineering Office of the City of Leipzig, the route network of OSM also includes routes in green spaces (for which the Office for Urban Green Areas and Waters is responsible), routes in semi-public and private spaces and partly also informal routes, which ultimately also represent significant connections for pedestrian traffic. The OSM routes dataset was only adjusted for those routes that cannot be walked on by pedestrians (e.g., freeways and freeway on-ramps). The geodata of the POIs were for the most part directly available to the city of Leipzig. They were supplemented by OSM data if no comprehensive citywide data sets were available. In some cases, data sets from both sources were merged and identified duplicates were removed. Some data sets were manually researched and added due to a lack of availability. In addition to the POIs available as point data, raster data for the population density and polygons as area data for the green, blue and open spaces as well as historical locations were integrated. Spatial movement data were also included to represent leisure travel (going for a walk, jogging). This was of particular relevance for the green spaces. The analysis implemented in this way is based on an extensive dataset of individual elements of significance such as POIs (6,629 records), resident grids (46,000 records), green and water areas (3,085 records), as well as the tracking data. Results Figure 1 shows the final significance map for the entire city of Leipzig and figure 2 shows a section of the inner city. The highest significance values of more than 650 points are found in Leipzig’s city center, where a particularly large number of catchment areas of stores, services, restaurants, educational institutions (especially universities) and public buildings overlap. In general, it is apparent that services, retail and gastron- Figure 2: Significance map for pedestrian traffic of a section of the inner city of Leipzig Source: Authors Urban mobility SCIENCE & RESEARCH International Transportation (71) 1 | 2019 43 omy clearly shape the areas of significance for pedestrian traffic due to their concentration. The centers of levels A to D defined in the 2016 urban development plan (Stadtentwicklungsplan, StEP) [9] also stand out accordingly. Hence, there is a good correspondence between the pedestrian traffic potentials determined with the method described here and the spatial development goals of the city of Leipzig. There is also close correlation in the grading of the centers, with some deviations. For example, the D-center Connewitzer Kreuz shows a very high and the C-center Eutritzsch/ Delitzscher Straße a rather low expression in the significance levels. The Band C-centers defined in the StEP 2016 have maximum significance levels of about 200 to 250, while the D-centers are between 100 to 150. There are also areas beyond the centers defined in the StEP 2016 with very high levels of significance, such as Johannisplatz, Bayerischer Platz, the Musikviertel, and elevated significance areas within the city and sub-centers, such as Coppiplatz, Stannebeinplatz, or the Zweinaundorf subcenter. This shows the potential of these areas for future development. Overall, areas with good accessibility in the network perform better. The more access points a node has and the more routes lead to a location, the more areas of influence tend to overlap there, which in turn leads to higher levels of significance. Summary and outlook The significance map now available for the city of Leipzig allows for the evidence-based identification of potentials and development priorities for pedestrian traffic on an urban scale for the first time. With reference to the significance map, it is now possible to prioritize and hierarchize all emerging initiatives and measures from the perspective of pedestrian traffic. Given the large number of necessary measures for pedestrian traffic in the entire urban area, such a systematic approach is imperative to enable the systematic and strategic classification of pedestrian traffic concerns under the constraints of financial and human resources, while taking into account the objectives formulated in the various strategic planning documents [1]. The approach based on geodata is transparent and transferable to other cities. Because of the way the approach differentiates between locations, it enables a balanced consideration of the demands of the highly urbanized settlement structures as well as the requirements of the outer and settlement areas and the suburban residential areas. In order to validate the estimated potentials and significance levels, a comprehensive survey of actual pedestrian volumes would be suitable; this would further improve the validity of the results and thus also the weight of the significance map as an instrument in planning. ■ REFERENCES [1] Stadt Leipzig: Fußverkehrsstrategie - Die Overtüre. https: / / static. leipzig.de/ fileadmin/ mediendatenbank/ leipzig-de/ Stadt/ 02.6_ Dez6_Stadtentwicklung_Bau/ 66_Verkehrs_und_Tiefbauamt/ Verkehrskonzepte/ Fussverkehrsstrategie_Online_202 1 .pdf. Accessed July 17, 2023. [2] Ewing, R., Connors, M. B., Goates, J. P., Hajrasouliha, A., Neckerman,K., Nelson, A. C., Greene, W.: Validating Urban Design Measures. [3] Gascon, M., Götschi, T., de Nazelle, A., Gracia, E., Ambròs, A., Márquez, S., Marquet, O., Avila-Palencia, I., Brand, C., Iacorossi, F., Raser, E., Gaupp-Berghausen, M., Dons, E., Laeremans, M., Kahlmeier, S., Sánchez, J., Gerike, R., Anaya-Boig, E., Panis, L. I., Nieuwenhuijsen, M. (2019): . Correlates of Walking for Travel in Seven European Cities: The PASTA Project. Environmental health perspectives, vol. 127, no. 9, , p. 97003. [4] Ewing, R., Cervero, R. (2010): Travel and the Built Environment. In: Journal of the American Planning Association, vol. 76, no. 3, pp. 265-294. [5] Kirkley, A., Barbosa, H., Barthelemy, M., Ghoshal, G. (2018): From the Betweenness Centrality in Street Networks to Structural Invariants in Random Planar Graphs. In: Nature communications, vol. 9, no. 1, p. 2501. [6] Aurich, A.: Modelle Zur Beschreibung Der Verkehrssicherheit Innerörtlicher Hauptverkehrsstraßennetze Unter Besonderer Berücksichtigung Der Umfeldnutzung. https: / / tu-dresden.de/ bu/ verkehr/ ivs/ vnm/ ressourcen/ dateien/ institutsschriftenreihe/ Heft- 14.pdf? lang=de. Accessed August 19, 2022. [7] FGSV (2002): Empfehlungen Für Fußgängerverkehrsanlagen. Köln: EFA. FGSV-Verlag. [8] Stadt Leipzig: Nahverkehrsplan Der Stadt Leipzig. Zweite Fortschreibung. https: / / static.leipzig.de/ fileadmin/ mediendatenbank/ leipzig-de/ Stadt/ 02.6_Dez6_Stadtentwicklung_Bau/ 66_ V e r k e h r s _ u n d _ T i e f b a u a m t / N a h v e r k e h r s p l a n / Z w e i t e - Fortschreibung-Nahverkehrsplan-Stadt-Leipzig-2019.pdf. Accessed July 17, 2023. [9] Stadt Leipzig: Stadtentwicklungsplan Zentren 2016. https: / / static. leipzig.de/ fileadmin/ mediendatenbank/ leipzig-de/ Stadt/ 02.6_ Dez6_Stadtentwicklung_Bau/ 61_Stadtplanungsamt/ Stadtentwicklung/ Stadtentwicklungsplaene/ STEP_Zentren/ STEP_Zentren_2016_Blaue-Reihe-Nr-62.pdf. Accessed July 17, 2023. Friedemann Goerl Stadt Leipzig, Verkehrs- und Tiefbauamt, Fußverkehrsverantwortlicher, Leipzig (DE) friedemann.goerl@leipzig.de Frederik Sander Stadt Leipzig, Verkehrs- und Tiefbauamt, Sachbearbeiter strategische Rad- und Fußverkehrsplanung, Leipzig (DE) frederik.sander@leipzig.de Caroline Koszowski Wiss. Mitarbeiterin, Integrierte Verkehrsplanung und Straßenverkehrstechnik, TU Dresden (DE) caroline.koszowski@tu-dresden.de Regine Gerike, Prof. Dr.-Ing. Integrierte Verkehrsplanung und Straßenverkehrstechnik, TU Dresden (DE) regine.gerike@tu-dresden.de Robert Guschel Stadt Leipzig, Stadtplanungsamt, Koordinierungsstelle “Leipzig weiter denken”, Leipzig (DE) robert.guschel@leipzig.de Trialog Publishers Verlagsgesellschaft | Schliffkopfstrasse 22 | D-72270 Baiersbronn Tel.: +49 7449 91386.36 | Fax: +49 7449 91386.37 | office@trialog.de | www.trialog-publishers.de Let’s keep in touch editorsdesk@international-transportation.com advertising@international-transportation.com