Alexander Sohr

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.

Self evaluation of floating car data based on travel times from actual vehicle trajectories

Floating Car Data (FCD) fleets are a valuable data source to obtain travel times as basis for traffic information or route guidance systems. To deliver reliable traffic information and to improve algorithms and systems for generating FCD from GPS positions their current quality has to be evaluated first. In this contribution the travel times from actual vehicle trips are compared with travel times for each edge on those trips as they result from the FCD algorithm. About 540,000 trajectories generated by more than 4,000 taxis at the four Wednesdays in October 2010 are the basis for this comparison.

Development of a demand responsive transport system with improvement analysis on conventional public transport: A case study for Schorndorf, Germany

Demand Responsive Transport (DRT) is a passenger-oriented branch of public transport, which consists of a group of passengers sharing a vehicle with flexible pick-up and drop-off locations and times. However, DRT systems are most of the time economically unfeasible, due to their difficulties on balancing costs and demand. The optimization problem associated with this kind of systems is known as the Dial-a-Ride problem. The purpose of this work is the development of a DRT system which solves this problem making use of an Ant Colony Optimization algorithm. A simulator provided with an evaluation tool analyzes the viability of the implementation of this system for the city of Schorndorf (40.000 inhabitants) in Germany. For its evaluation, the proposed system has been compared to the already existing conventional public transport system in this city, analyzing different parameters related to quality of service and required efforts.

Fundamental Diagram of Traffic Flows on Urban Roads: Local Versus Whole-Link Approaches

Fundamental diagrams of traffic flow variables have been quite useful in determining freeway operations quality. However, they are usually not used for that purpose on urban roads. This work is an approach toward utilizing the fundamental diagram on urban roads. On the basis of a host of empirical and simulation work, the first steps toward a routine application of the fundamental diagram are sketched. In addition, two approaches are compared, the first uses a traditional fundamental diagram as measured by loop detectors, and the second uses a whole-link approach relating link–travel–speed with volume. The travel times in particular, contain important information that can be used for traffic management applications.