SUPERVISOR: Yusak SUSILO

PROJECT ASSIGNED TO: Johannes BRUNNER

This project investigates the traffic performance of shared street space. Shared space schemes aim to improve urban public life while maintaining streets’ role as mobility infrastructure (see also Hamilton-Baillie, 2008a; Hamilton-Baillie, 2008b). By removing strict physical segregation between traffic modes, these designs promote interactions between users, shifting away from rule-based behaviors. In addition, shared spaces often include design elements such as plantings and seating to foster social activity and encouraging traffic calming, creating pleasant public environments that encourage social activity. While shared spaces promise to create pedestrian-friendly, vibrant streets and improve neighborhood life by reducing traffic speeds (see also Appleyard, 1980), their effects on traffic flow, safety, and user comfort remain insufficiently understood. As more cities implement shared space schemes worldwide, a critical question arises: can fully shared spaces serve as a universal solution for traffic calming, or do their impacts depend on context-specific conditions? 

Existing studies suggest that user perceptions of safety and comfort vary when traffic modes mix freely (see also Kaparias et al., 2012; Zhang et al., 2023). Additionally, it is still underdeveloped how the absence of structure in shared space affects traffic flow. While several microscopic simulation models have been developed for shared space (e.g. Anvari et al., 2015; Schönauer, 2017; Slack-Smith et al., 2024), they primarily focus on the individual-level movement rather than the aggregate dynamics of mixed traffic under high-density conditions. Moreover, current models lack a quality-of-service assessment that integrates comfort, safety, and efficiency – factors that are critical for urban mobility planning. In urban planning practice, shared spaces are designed using a mix of guidelines, heuristics, and empirical knowledge, yet a systematic understanding of how traffic dynamics influence shared space performance is still lacking. 

This PhD research seeks to bridge the gap between individual user behavior, aggregate traffic characteristics, and shared space design principles. Focusing on pedestrians and cyclists, the project investigates: 

  1. How do cyclists navigate through high-density pedestrian environments, and how do their interactions with individuals and groups shape traffic flow?
  2. How does the mixing of multi-directional pedestrian and cyclist flows impact shared space efficiency and user experience?
  3. What design principles can optimize shared space performance across different cyclist-to-pedestrian volume ratios? 

The project follows a data-driven modeling approach that involves the microscopic simulation of agents in shared space scenarios (similar to Dias et al., 2018; Guo et al., 2020; Wang et al., 2024). The data collection includes empirical observations of microscopic characteristics as well as a stated preference survey that inform the decision-making in the model. The model is developed – and validated using the data sources – to test shared space scenarios under different user compositions and densities. For the representation of quality of service, a set of performance indicators (KPIs) is established, considering aspects of traffic flow and comfort of individual agents (see also Ewing and Handy, 2009; Cepolina et al., 2018; Nikiforiadis et al., 2020). Based on the KPIs, the model is used to systematically evaluate infrastructural configurations and derive shared space design principles.

By bridging individual user behavior, aggregate traffic dynamics, and urban design principles, this research will generate quantitative insights for optimizing street configurations. Building on behavioral insights and methodological contributions, this project aims to provide policymakers and planners with guidelines and tools supporting the successful implementation of shared street spaces.

Figure 1: Mixed-traffic in a shared space street environment (Brunner, 2025)

 

References

Anvari, B., M.G.-H. Bell, A. Sivakumar and W.Y. Ochieng (2015) Modelling shared space users via rule-based social force model, Transportation Research Part C: Emerging Technologies, 51, 83-103.

Appleyard, D. (1980) Livable streets: Protected neighborhoods? The ANNALS of the American Academy of Political and Social Science, 451, 106-117

Cepolina, E.M., F. Menchini and P. Gonzales Rojas (2018) Level of service of pedestrian facilities: Modelling human comfort perception in the evaluation of pedestrian behaviour patterns, Transportation Research Part F: Traffic Psychology and Behaviour, 58, 365-381.

Dias, C., H. Nishiuchi, S. Hyoudo and T. Todoroki (2018) Simulating interactions between pedestrians, segway riders and cyclists in shared spaces using social force model, Transportation Research Procedia, 34, 91-98.

Ewing, R. and S. Handy (2009) Measuring the unmeasurable: Urban design qualities related to walkability, Journal of Urban Design, 14 (1), 65-84.

Guo, N., R. Jiang, S.C. Wong, Q.Y. Hao, S.Q. Xue, Y. Xiao and C.Y. Wu (2020) Modeling the interactions of pedestrians and cyclists in mixed flow conditions in uni- and bidirectional flows on a shared pedestrian-cycle road, Transportation Research Part B: Methodological, 139, 259-284.

Hamilton-Baillie, B. (2008a) Shared space: Reconciling people, places and traffic, Built Environment, 34 (2), 161-181.

Hamilton-Baillie, B. (2008b) Towards shared space, Urban Design International, 13 (2), 130-138

Kaparias, I., M.G.-H. Bell, A. Miri, C. Chan and B. Mount (2012) Analysing the perceptions of pedestrians and drivers to shared space, Transportation Research Part F: Traffic Psychology and Behaviour, 15 (3), 297-310.

Nikiforiadis, A., S. Basbas and M.I. Garyfalou (2020) A methodology for the assessment of pedestrians-cyclists shared space level of service, Journal of Cleaner Production, 254, 120172.

Schönauer, R. (2017) A Microscopic Traffic Flow Model for Shared Space, Doctoral Thesis, Graz University of Technology.

Slack-Smith, D., K.P. Wijayaratna and M. Zeibots (2024) The development of modeling shared spaces to support sustainable transport systems: Introduction to the Integrated Pedestrian–Vehicle Model (IPVM), Sustainability, 16 (10), 4227.

Wang, W., H. Zhou, J.T.Y. Lo, S.M. Lo and Y. Wang (2024) A modified social force model for pedestrian-bicycle mixed flows and its application on evaluating the conflict risk in shared roads, Physica A: Statistical Mechanics and its Applications, 643, 129788.

Zhang, C., B. Du, Z. Zheng and J. Shen (2023) Space sharing between pedestrians and micro-mobility vehicles: A systematic review, Transportation Research Part D: Transport and Environment, 116, 103629.