Journal of Cleaner Production publication: Simulation of e-bike systems.

We just published another article on simulation of e-bike sharing station, focusing on simulating demand parameters and optimizing station design (e.g., number of bikes, batteries etc). Our TRR paper is still in press too and can be downloaded here. 

Electric bike sharing: simulation of user demand and system availability  

Shuguang Ji, Christopher R. Cherry, Lee D. Han, David A. Jordan

Suggested Citation:
Ji, S., Cherry, C.R., Han, L.D., Jordan, D.A. (2013) Electric bike sharing: simulation of user demand and system availability. Journal of Cleaner Production. DOI:10.1016/j.jclepro.2013.09.024 (In Press).

You can download the preprint here: https://www.dropbox.com/s/z96yxta9ug12a3j/EbikeR_Final_Submit-Preprint.pdf

Abstract: 

This paper describes the operational concepts and system requirements of a fully automated electric bike (e-bike) sharing system demonstrated through a pilot project at the University of Tennessee, Knoxville (UTK) campus (deployed in September 2011). This project is part of a movement to develop a sustainable transportation system, and is one of the green initiatives on UTK campus. E-bikes are more energy efficient and produce fewer greenhouse gas (GHG) emissions per person compared to other transport modes such as car, bus, and motorcycle. Without empirical demand information for an e-bike sharing system, we simulated the operations of such a system to gain insights during the design process before field deployment.  The simulation exercise focused on three critical demand parameters – distributions of trip rates, trip lengths, and trip durations – and coupled them with supply parameters – number of e-bikes, number of swappable batteries, and battery recharging profiles. The primary purpose of these simulations is to evaluate the efficiency of an off-board battery recharging system, where the depleted battery is removed from an e-bike upon its return and inserted into one of the charging slots at the kiosk. We tested various scenarios with different number of batteries always maintaining an initial condition with the battery to e-bike ratio greater or equal to 1.0 to ensure battery availability. We applied empirical battery recharging rates and system operations rules to determine the number of e-bikes and batteries available under different potential demand situations, with a focus on optimizing the number of batteries to meet user demands. By adjusting input parameters, numerous scenarios were simulated for sensitivity analysis. Based on the results of the simulation, this paper presents a cost constrained e-bike sharing system design that can maintain a high level of system reliability (e-bike and battery availability) through optimal battery charging and distribution management. We found that high demand scenarios require multiple swappable batteries per e-bike to reasonably meet the maximum demand. Trip duration has the most influence on e-bike and battery availability, followed by trip rate, and then trip length.

Report: Findings from first year

There has been a flurry of interest in our program from around the world over the past several weeks. It seems that e-bike sharing is getting more mainstream. Many have asked for data or information on our system use. We have one published paper that describes some of our main findings from our first year, to be published in the Transportation Research Record soon. Instead of waiting, below is a link to the peer-reviewed preprint. We will update the file when the final paper is ultimately published. We have a couple of other interesting papers coming out of this system so stay tuned.

 North America’s first e-bike share: A year of experience

cycleUshare is back...sort of

Greetings. We've been getting some queries related to the e-bikeshare on UTK campus along the lines of "what's going on with the system?". Those around campus might have noticed we shut down the system over the summer to reduce our maintenance requirements (when most of our registered users are gone) and to give us time to reflect on next steps. This project was conceived to meet a few objectives -- research, education, service, and technology creation. We were given a limited timeline to do this by the campus administration, a pilot test with a sunset date (last spring). We've met many of those objectives. We have a couple of journal articles in press, Casey Langford finished his dissertation using the e-bikeshare system as a platform that will create a couple of more journal articles, we've presented the research at (inter)national conferences, we've presented the technology to the public at many venues, we've worked to disseminate the technology to others who can replicate it. However, without approval from administrators and a clearly sustainable direction, we could not move forward aggressively on next steps, thus we've been quiet until now. We can officially say now that the UT administration has given us approval (last week) to continue operating the system for the sake of the research and all the other benefits that come from that. We are now in the process of assessing the relaunch strategy, working through new technology development and generating a sustainable funding stream for the system operation and research endeavors. As we move forward, we will give more information, but we intend to get the system back up and running this semester, hopefully while the weather is nice. If you are interested in using the system, click on the volunteer form and give us your information and we will contact you when we get the system back online. Thanks to the UT community and administration for supporting this endeavor.

CycleUshare Research Paper Accepted at Major Transportation Conference

The first paper that we wrote related to the operation of this project has been accepted to the Transportation Research Board Annual Meeting in Washington DC in January. The paper received strong reviews and will hopefully make it into the Transportation Research Record Journal. Many of our users were a part of the study either passively (by using the system) or actively (by us interviewing them and discussing particular trips). A sneak preview of the paper:

North America’s first electric bicycle share: A year of experience 

by B.C. Langford, C. Cherry, T. Yoon, S. Worley, and D. Smith 

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Abstract

The integration of electric bicycles (e-bikes) with bicycle sharing can potentially increase the utility of bike sharing by reducing some barriers to bicycling and increasing the amount of prospective users. North America’s first e-bike sharing system (cycleUshare) at the University of Tennessee, Knoxville, offers a new, sustainable transportation option for students, faculty, and staff.  The cycleUshare system is a small pilot test with two stations to research the technology and user experiences. This paper presents an overview of the cycleUshare system and reports experiences from the first year of operation. With 93 enrolled users, cycleUshare provides a unique opportunity to study not only the system use, but also how individual users make trips with both regular and electric bicycles and the factors that influence those trips. The study finds that only 22% of users account for 81% of the trips. Factors of speed and convenience play major roles in participant’s decisions to use the system, and speed and comfort are the most influential factors in selection of an e-bike over a regular bicycle. Most of the reported trips are class related, although e-bikes are found to be used for a wide variety of trip purposes. Walking is the mode most displaced by the system indicating that e-bike sharing expands user mobility. Additionally user perceptions about bicycle types are explored. This model of electric bicycle sharing is found to be effective at attracting users to both regular and electric bicycles and is capable of expanding user mobility.

Still Moving Forward on New Software/Electronics

New Bike and Battery Rack Controller

Our systems are still running, but with some reliability problems. We have two problems (one at each station) that are both software related in different ways. We are very excited with the results of some of our field tests (you might notice the five positions on the right of the Ag Campus station are shut down for testing). The next step is tying it all together with a slick user interface, or a functional one at least. We have great programmers/electrical engineers from University of Tennessee and a recent grad from University of Washington working hard on getting a robust solution on the ground, which is quite exciting.

Field testing

Though delayed, our new system that will be released to the world with be modular, compact, efficient, customizable, and non-proprietary. 

Welcome to the new academic year

Welcome new students and staff and welcome back old users. We've gotten a lot of interest in participating in our system in the last couple of days with all the new students seeing our system. Our new software and electronics is still coming. We're going through some lab testing now to get it in good shape for public consumption. Unfortunately our big-time friends who are currently premier bikeshare company are having new software rollout delays too so we're not alone (http://bit.ly/NsMQUN). In the meantime, we'll get more aggressive about adding users into our system, though there will be a little bit of learning and relearning once we get our new software out. Also, since we're starting with a bunch of new users with our old software, everyone please pay careful attention to instructions. Our old (current) software can't handle user error. Our new (future) software will be a little more robust. Also make sure you watch the quick how-to video before you get to the station.