Category Archives: Publications

Mobility Patterns in Shared, Autonomous, and Connected Urban Transport

N. Ronald, Z. Navidi, Y. Wang, M. Rigby, S. Jain, R. Kutadinata, R. Thompson, and S. Winter, “Mobility patterns in shared, autonomous, and connected urban transport,” in Disrupting Mobility: Impacts of sharing economy and innovative transportation on cities, ser. Lecture Notes in Mobility, G. Meyer and S. Shaheen, Eds. Springer, 2017.

Abstract:

A number of recent technological breakthroughs promise disrupting urban mobility as we know it. But anticipating such disruption requires valid predictions: disruption implies that predictions cannot simply be extrapolations from a current state. Predictions have to consider the social, economic and spatial context of mobility. This paper studies mechanisms to support evidence-based transport planning in disrupting times. It presents various approaches, mostly based on simulation, to estimate the potential or real impact of the introduction of new paradigms on urban mobility, such as ad-hoc shared forms of transportation, au-tonomously driving electrical vehicles, or IT platforms coordinating and integrating modes of transportation.

Automated Urban Travel Interpretation: A Bottom-up Approach for Trajectory Segmentation

R. Das and S. Winter, “Automated Urban Travel Interpretation: A Bottom-up Approach for Trajectory Segmentation,” Sensors, vol. 16, no. 11, 2016.

Abstract:

Understanding travel behavior is critical for an effective urban planning as well as for enabling various context-aware service provisions to support mobility as a service (MaaS). Both applications rely on the sensor traces generated by travellers’ smartphones. These traces can be used to interpret travel modes, both for generating automated travel diaries as well as for real-time travel mode detection. Current approaches segment a trajectory by certain criteria, e.g., drop in speed. However, these criteria are heuristic, and, thus, existing approaches are subjective and involve significant vagueness and uncertainty in activity transitions in space and time. Also, segmentation approaches are not suited for real time interpretation of open-ended segments, and cannot cope with the frequent gaps in the location traces. In order to address all these challenges a novel, state based bottom-up approach is proposed. This approach assumes a fixed atomic segment of a homogeneous state, instead of an event-based segment, and a progressive iteration until a new state is found. The research investigates how an atomic state-based approach can be developed in such a way that can work in real time, near-real time and offline mode and in different environmental conditions with their varying quality of sensor traces. The results show the proposed bottom-up model outperforms the existing event-based segmentation models in terms of adaptivity, flexibility, accuracy and richness in information delivery pertinent to automated travel behavior interpretation.

Detecting Urban Transport Modes Using a Hybrid Knowledge Driven Framework from GPS Trajectory

R. Das and S. Winter, “Detecting Urban Transport Modes Using a Hybrid Knowledge Driven Framework from GPS Trajectory,” ISPRS International Journal of Geo-Information, vol. 5, no. 11, 2016 (open access).

Abstract:

Transport mode information is essential for understanding people’s movement behavior and travel demand estimation. Current approaches extract travel information once the travel is complete. Such approaches are limited in terms of generating just-in-time information for a number of mobility based applications, e.g., real time mode specific patronage estimation. In order to detect the transport modalities from GPS trajectories, various machine learning approaches have already been explored. However, the majority of them produce only a single conclusion from a given set of evidences, ignoring the uncertainty of any mode classification. Also, the existing machine learning approaches fall short in explaining their reasoning scheme. In contrast, a fuzzy expert system can explain its reasoning scheme in a human readable format along with a provision of inferring different outcome possibilities, but lacks the adaptivity and learning ability of machine learning. In this paper, a novel hybrid knowledge driven framework is developed by integrating a fuzzy logic and a neural network to complement each other’s limitations. Thus the aim of this paper is to automate the tuning process in order to generate an intelligent hybrid model that can perform effectively in near-real time mode detection using GPS trajectory. Tests demonstrate that a hybrid knowledge driven model works better than a purely knowledge driven model and at per the machine learning models in the context of transport mode detection.

Cost-efficient Co-modal Ride-sharing Scheme Through Anticipatory Dynamic Optimisation

R. Kutadinata, R. Thompson, and S. Winter, “Cost-efficient Co-modal Ride-sharing Scheme Through Anticipatory Dynamic Optimisation,” in Proceedings of the 23rd ITS World Congress, 2016.

Abstract:

This paper considers the vehicle routing problem when dealing with a co-modal demand-responsive transport service. The vehicles in the service are shared among two modes of customers, passengers and goods deliveries. In particular, this paper develops a conceptual model in order to explore the performance of such a service with two different optimisation algorithms, namely deterministic re-optimisation and the Multiple Scenario Approach (MSA). An important contribution of this work is the formulation of the co-modality as a pick-up and delivery problem with time windows (PDPTW). In addition, the effect of using various constraints and penalty functions in the optimisation formulation will be investigated. The experiment will be carried out in a vehicle routing simulation developed in MATLAB by using a demand scenario obtained from the Victorian Integrated Survey of Travel and Activity (VISTA) data. In the model, the performance of the algorithms is measured by the operating cost, the number of customers whose time-window constraints are violated, and the average wait and detour time.

Autonomous car and ride sharing: flexible road trains

N. Agatz, A. Bazzan, R. Kutadinata, D. Mattfeld, M. Sester, S. Winter, and O. Wolfson, “Autonomous car and ride sharing: flexible road trains,” (vision paper), in Proceedings of the 24th ACM SIGSPATIAL, 2016.

This paper won the Best Vision Paper award and the CCC Blue Sky Ideas award. Read more in the CCC website.

Abstract:

Since in many cities transport infrastructure is operating at or beyond capacity, novel approaches to organize urban mobility are gaining attraction. However, assessing the benefi ts of a measure that has disruptive capacity in a complex system requires a carefully designed research. This paper takes a recent idea for urban mobility – flexible road trains – and illustrates the computational and research challenges of realizing its full potential and describing its social, ecological and economical impact.

Activity-based ridesharing: Increasing flexibility by time geography

Y. Wang, R. Kutadinata, and S. Winter, “Activity-based ridesharing: Increasing flexibility by time geography,” in Proceedings of the 24th ACM SIGSPATIAL, 2016.

Abstract:

Ridesharing is an emerging travel mode that reduces the total amount of traffic on the road by combining people’s travels together. While present ridesharing algorithms are tripbased, this paper aims to achieve signi cantly higher matching chances by a novel, activity-based algorithm. The algorithm expands the potential destination choice set by considering alternative destinations that are within given space-time budgets and would provide a similar activity function as the originals. In order to address the increased combinatorial complexity of trip chains, the paper introduces an efficient space-time filter on the foundations of time geography to search for accessible resources. Globally optimal matching is achieved by binary linear programming. The ridesharing algorithm is tested with a series of realistic scenarios of diff erent population sizes. The encouraging results demonstrate that the matching rate by activity-based ridesharing is signi cantly increased from the baseline scenario of traditional trip-based ridesharing.

A Neuro-Fuzzy based Hybrid Intelligent Framework for Transport Mode Detection

R. Das and S. Winter, “A Neuro-Fuzzy based Hybrid Intelligent Framework for Transport Mode Detection,” in Proceedings of the 6th International Workshop on Mobile Entity
Localization, Tracking and Analysis (MELT)
, 2016.

Abstract:

Understanding transport mode detection, is important to transport planning and movement behavior analysis. In order to detect the transport modalities from GPS trajectories, various machine learning approaches have already been explored. However, the majority of them produce only a single conclusion from a given set of evidences, ignoring the uncertainty of any mode classi cation. Also, the existing machine learning approaches fall short in explaining their reasoning scheme. In contrast, a fuzzy expert system can explain its reasoning scheme in a human readable format with more exibility, but lacks the adaptivity and learning ability of machine learning. In this paper, a novel multi-layered hybrid intelligent framework is developed by integrating a fuzzy logic and a machine learning approach to complement each other’s limitations. Thus in this paper an intelligent fuzzy logic-based near-real time mode detection framework is presented that can perform comparable to state-of-the-art machine learning approaches by bridging the trade-off between explanatory power and prediction accuracy of the models. The results demonstrate that the proposed framework has achieved the aim in the context of near-real time transport mode detection.

Conventionalized gestures for the interaction of people in traffic with autonomous vehicles

S. Gupta, M. Vassardani, and S. Winter, “Conventionalized gestures for the interaction of people in traffic with autonomous vehicles,” in Proceedings of the 9th International Workshop on
Computational Transportation Science
, 2016.

Abstract:

The fi rst autonomous vehicles are already tested in the public traffic . The rapid development in bringing this technology on roads attracts growing attention of research in the human interaction with autonomous vehicles. This paper focuses on the interaction of other road users with autonomous vehicles. These road users may be pedestrians who negotiate their right of way, other human drivers sharing the same road, or human traffic control officers. In order to learn about these road users in general, this paper aims to identify fi rst the formalized hand signals applied by officers. The paper answers the question whether there is a general and universal language to interact with traffic. If so, then future work can identify elements of this universal language in the gestures of other road users, and facilitate an understanding between them and autonomous vehicles.

Predicting susceptibility to use demand responsive transport using demographic and trip characteristics of the population

S. Jain, N. Ronald, R. Thompson, and S. Winter, “Predicting susceptibility to use demand responsive transport using demographic and trip characteristics of the population”, Travel Behaviour and Society, 6:44-56, 2017

Abstract:

Shared transportation providing point-to-point services on demand, although not an unknown element in urban mobility, has started gaining more presence with the growth of information technology in the transport sector. These forms of transport modes will supplement or compete with the existing public and private transport. Their mixed reception in the past is a matter of concern especially before making investment decisions. To find feasible opportunities of implementation, an estimation of the demand patterns in the target city is desirable. This paper will provide and evaluate a methodology for this estimation that avoids ambivalent and expensive user preference surveys. Demand patterns are caused by the spatial variation of demographic characteristics, and travel behavior over the city. Usability patterns of the proposed services can be learned from the experience of similar services operating elsewhere. Variations of the identified favorable characteristics can be found out in the target city using travel surveys of a population sample. The resulting spatial patterns can be used to find the more favorable areas for implementation of such transport modes. The methodology can be validated by applying it on the existing transport modes in the target city, which will also help in understanding the nature of competition among the proposed and existing transport modes. As the review of operating services is generic, it can be used in conjunction with respective travel surveys in different places. Similarly, a review can be done for any proposed transport mode and provided methodology can be applied for exploring demand patterns.

Comparing demand responsive and conventional public transport in a low demand context

Navidikashani, Z., Ronald, N., & Winter, S. (2016, March). Comparing demand responsive and conventional public transport in a low demand context. In 2016 IEEE International Conference on Pervasive Computing and Communication Workshops (PerCom Workshops)

Abstract:

Considering the sprawl of the cities, the conventional public transport (CPT) with fixed route and fixed schedule becomes less efficient and desirable every day. However, the emerging technologies in computation and communication are facilitating more adaptive types of public transport, such as Demand Responsive Transport (DRT) systems, which operate according to the demand. It is crucial to study the feasibility and advantages of these systems before implementation to prevent failure and financial loss. In this work, a realistic model is provided by incorporating a dynamic routing algorithm into an agent-based traffic simulation to compare DRT and CPT. This model provides a high spatial and temporal granularity, which makes it possible to analyze the results on an individual level. The results showed that replacing CPT with DRT will improve the mobility by decreasing the perceived travel time by passengers and without any extra cost under certain circumstances.