Joschka Bischoff

Simulation of City-wide Replacement of Private Cars with Autonomous Taxis in Berlin

Abstract Autonomous taxi (AT) fleets have the potential to take over a significant amount of traffic handled nowadays by conventionally driven vehicles (CDV). In this paper, we simulate a city-wide replacement of private cars with AT fleets of various sizes. The simulation model comprises microscopic demand for all private car trips in Berlin (including incoming and outgoing traffic), out of which the internal ones are exclusively served by ATs. The proposed real-time AT dispatching algorithm was optimized to handle hundreds of thousands of vehicles and millions of requests at low computing times. Simulation results suggest, that a fleet of 100 000 vehicles will be enough to replace the car fleet in Berlin at a high service quality for customers. Based on this, one AT could replace the demand served by ten CDVs in Berlin.

An Assignment-Based Approach to Efficient Real-Time City-Scale Taxi Dispatching

This study proposes and evaluates an efficient real-time taxi dispatching strategy that solves the linear assignment problem to find a globally optimal taxi-to-request assignment at each decision epoch. The authors compare the assignment-based strategy with two popular rule-based strategies. They evaluate dispatching strategies in detail in the city of Berlin and the neighboring region of Brandenburg using the microscopic large-scale MATSim simulator. The assignment-based strategy produced better results for both drivers (less idle driving) and passengers (less waiting). However, computing the assignments for thousands of taxis in a huge road network turned out to be computationally demanding. Certain adaptations pertaining to the cost matrix calculation were necessary to increase the computational efficiency and assure real-time responsiveness.

Large-scale Microscopic Simulation of Taxi Services

The paper presents research on large-scale microscopic simulation of taxi services in Berlin based on floating car data collected by the Taxi Berlin fleet, the largest taxi association in Germanys capital. Firstly, Berlins taxi market is shortly described and the demand and supply data obtained from FCD analysed. Secondly, the online taxi dispatching problem formulation for this specific case is given, followed by the definition of two real-time rule-based heuristics used to dispatch taxis dynamically within the simulation. Finally, the simulation setup in MATSim is described, and the results obtained with both heuristics are analysed and compared in terms of dispatching performance, proving the effectiveness of the second strategy at different demand scales.

Analysis of Berlin's taxi services by exploring GPS traces

With current on-board GPS devices a lot of data is being collected while operating taxis. This paper focuses on analysing travel behaviour and vehicle supply of the Berlin taxi market using floating car data (FCD) for one week each in 2013 and 2014. The data suggests that there is generally a demand peak on workday mornings and a second peak over a longer time in the afternoon. On weekends, the demand peaks shift towards the night. On the supply side, drivers seem to adapt to the demand peaks very efficiently, with fewer taxis being available at times of low demand, such as during midday. A spatial analysis shows that most taxi trips take place either within the city centre or from/to Tegel Airport, the citys largest single origin and destination. Drivers spend a large amount of their work time on waiting for customers and the taxi rank at Tegel Airport is the most popular one.

Large-scale microscopic simulation of taxi services. Berlin and Barcelona case studies

The paper presents research on large-scale microscopic simulation of taxi services in Berlin and Barcelona based on floating car data collected by local taxi fleets. Firstly, Berlin’s and Barcelona’s taxi markets are shortly described and the demand and supply data obtained from FCD analysed. Secondly, the online taxi dispatching problem formulation for this specific case is given, followed by the definition of two real-time rule-based heuristics used to dispatch taxis dynamically within the simulation. Finally, the simulation setup in MATSim is described, and the results obtained with both heuristics are analysed and compared in terms of dispatching performance, proving the effectiveness of the second strategy at different demand and supply scales. This paper is an extended version of Maciejewski and Bischoff 2015, where only the Berlin case study was presented.

Integrating explicit parking search into a transport simulation.

Abstract: Explicit parking search is not widely integrated into transport simulation and transport models. In this paper, the integration of a parking search simulation into MATSim (Multi-Agent Transport Simulation) is demonstrated. This includes the integration into the agents simulation logic using within-day re-planning methodology, a separation up of car trips into several segments for each stage of the trip, a parking search behavior and a data structure for parking infrastructure. The parking search model is applied in a case study for an area in Berlin, Germany. Compared to a standard simulation without parking search, results suggests that parking search traffic sums up to 20 per cent of the overall traffic in a residential area and has a significant impact on the overall travel times of agents traveling by car.

Towards a Testbed for Dynamic Vehicle Routing Algorithms

Since modern transport services are becoming more flexible, demand-responsive, and energy/cost efficient, there is a growing demand for large-scale microscopic simulation platforms in order to test sophisticated routing algorithms. Such platforms have to simulate in detail, not only the dynamically changing demand and supply of the relevant service, but also traffic flow and other relevant transport services. This paper presents the DVRP extension to the open-source MATSim simulator. The extension is designed to be highly general and customizable to simulate a wide range of dynamic rich vehicle routing problems. The extension allows plugging in of various algorithms that are responsible for continuous re-optimisation of routes in response to changes in the system. The DVRP extension has been used in many research and commercial projects dealing with simulation of electric and autonomous taxis, demand-responsive transport, personal rapid transport, free-floating car sharing and parking search.

Simulation-based optimization of service areas for pooled ride-hailing operators

Abstract Dynamic ride hailing with passenger pooling has become a popular form of urban transport and is a growing sector around the globe. The area where these services operate is often limited to densely populated inner city districts, whereas non-pooled options are often available in larger areas. In this paper, we introduce a simulation-based methodology that allows to optimize the service area of a ride hailing service using an agent-based simulation and apply it to the taxi demand of Berlin, Germany. Three different criteria are used for the optimization, which take the average vehicle occupancy, the revenues collected per area or both into account. The results show that for the given parameters a service area that focuses on an extended central area and some areas around may be profit-maximizing for operators.

Impact assessment of dedicated free-floating carsharing parking

Free-floating carsharing (FFC) has become an established mode of transport in many cities world-wide and may help to reduce private car ownership in densely populated urban areas. However, parking FFC vehicles in residential areas is often problematic and this reduces the overall attractiveness of such systems. In this paper, a simulation based assessment is proposed to evaluate the impact of designated FFC parking spaces in a residential area in Berlin. For this, FFC vehicles and their users are integrated into an existing MATSim transport model that takes into account explicit parking search. Results suggest, that the creation of designated FFC parking spaces may help to increase the share of that mode in the area significantly and at the same time reduce private car usage.

Electric Taxis in Berlin – Analysis of the Feasibility of a Large-Scale Transition

Battery operated electric vehicles (BEVs) offer the opportunity of running a zero-emission car fleet. However, due to their current range constraints, electric vehicle operations are mainly attractive for inner-city transport, such as the taxi business. This paper is bringing together facts and assumptions about Berlin’s taxi transport and the current conditions of BEVs in Germany to provide the scope of electrification. Firstly, the necessary amount of fast chargers is determined taking general constraints of Berlin’s taxi business into account. For charging, especially busy days during cold winter days will be critical. Furthermore, a pricing scheme for fast charger usage is introduced. Based on this, operating operation costs of a hybrid electric vehicle and a battery electric vehicle are compared. The authors conclude that BEV operation will only pay off if the vehicle’s battery life can be warranted over a long span or costs of electric energy in Germany drops.