סמינר מחלקתי

Enhancing Bike-Sharing Systems:  Parking Reservation Policies and Maintenance Operations

Mor Kaspi, Tel-Aviv University, Department of Industrial Engineering

Abstract:

We discuss two aspects that can enhance the operation of bike-sharing systems: (1) implementation of parking reservation policies, and (2) planning of maintenance operations. 

Under parking reservation policies, users may be required, upon renting a bicycle, to reserve a parking space (locker) at their destination and these spaces are kept for them. We propose several parking reservation policies, including a complete parking reservation (CPR) policy, under which all users are required to reserve a parking space. Other policies require the users to make reservations in certain cases only, or not at all. Using a Markovian model of a simplified system and simulation of real world systems we compare the proposed policies. In addition, we devise mathematical programming based bounds on the total excess travel time under any parking space reservation policy. Our results demonstrate the effectiveness of the simple CPR policy and suggest that parking space reservations should be used in practice, even if only a small share of the users are required to place reservations.

 Maintenance operations are crucial for the smooth operation of bike sharing systems. In these systems a small percentage of the bicycles become unusable every day. Currently, there is no reliable on-line information that indicates the usability of bicycles. We present a model that estimates the probability that a specific bicycle is unusable, based on available trip transactions data. Further on, we present some information based enhancements of the model and discuss an equivalent model for detecting locker failures.

Next, given reliable information regarding unusable bicycles, we study their impact on the quality of service. We model user dissatisfaction by a weighted sum of the expected shortages of bicycles and lockers as a function of the initial inventory of usable and unusable bicycles. We analyze and prove the convexity of the resulting bivariate function and accurately approximate it by a convex polyhedral function. The fitted polyhedral function can later be used in linear optimization models for operational and strategic decision making in bike sharing systems. Our numerical results demonstrate the high effect of the presence of unusable bicycles on user dissatisfaction. This in return emphasizes the need for having accurate real-time information regarding bicycle usability.    

This study was carried out under the supervision of Dr. Tal Raviv and Prof. Michal Tzur

ההרצאה תתקיים ביום שלישי 19.05.15, בשעה 14:00, בחדר 206, בניין וולפסון הנדסה, הפקולטה להנדסה , אוניברסיטת תל-אביב