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Publication Number: FHWA-HRT-10-025
Date: June 2010
Operating Characteristics of the Segway™ Human Transporter
The SegwayTM Human Transporter (HT), shown in figure 1, is one of several low-speed transportation devices (e.g., bikes, scooters, and wheelchairs) that, under certain circumstances, travels on sidewalks, roadways, and other shared-use paths. The SegwayTM HT is a motorized device that can achieve a top speed of 12.5 mi/h (20.1 km/h). Riders operate the device in a standing position, which allows the SegwayTM HT to have a relatively small footprint. It is necessary to study riders' behavior under naturalistic sidewalk travel conditions to accommodate SegwayTM HT traffic. However, there is little prior research describing the operating characteristics of SegwayTM HTs under these conditions, and therefore, there is little empirical data to guide traffic engineers, planners, and policy makers.
Figure 1. Photo. A rider on a SegwayTM HT.
A SegwayTM HT rider has to manage speed, maneuver the device, pass a variety of objects, and stop in response to environmental stimuli including people, traffic signals, curbs, and obstructions such as light poles and park benches. The available empirical research on the SegwayTM HT is limited. Current literature offers some insight into several performance characteristics, including travel speeds, perception-reaction time, and braking distances. The goal of this research was to answer the following questions:
The SegwayTM HT made its debut among a small group of users in 2001, and manufacturers began selling it to the general public in early 2003. It is marketed as a self-balancing transportation machine that runs on battery power and uses a combination of gyroscopes, tilt sensors, and computer processors to maintain balance. Table 1 lists the specifications of the i Series SegwayTM HT.
1 mi = 1.61 km 1 lb = 0.454 kg * Indicates that the speed limiting control keys act as a governor to limit the top speed of the SegwayTM HT.
SegwayTM HT regulations such as minimum age requirements; helmet use; and road, sidewalk, and trail use vary by State and community with some jurisdictions having no current regulations. According to the Governors Highway Safety Association, as of November 2008, 43 States and Washington, DC, have enacted legislation allowing the use of SegwayTM HTs, 5 States have no legislation, and 2 States have no statewide prohibitions.(2)
In 2006, the Consumer Products Safety Commission indicated that approximately 23,000 SegwayTM HTs were in operation.(3) Although the actual number of SegwayTM HT riders is unknown, there is still a need to ensure safety. However, there is little available literature on the evaluation of SegwayTM HT usage or safety. Instead, a small number of papers have reported comparison evaluations of the SegwayTM HT among a larger class of personal transportation devices such as motorized scooters, wheelchairs, and bicycles. One issue that needs to be studied is how SegwayTM HT riders interact with other non-SegwayTM HT users on shared-use paths and roadways.
Some non-Federal Highway Administration (FHWA) literature has described the SegwayTM HT in the context of benefits and costs to individual riders and society. Liu and Parthasarathy provided an overview of the potential benefits of riding SegwayTM HTs (e.g., pollution reduction) and potential challenges (e.g., the cost of the device).(4) Litman and Blair suggest features for characterizing different personal mobility devices, including the SegwayTM HT.(5) They characterized the SegwayTM HT as having medium societal value, medium congestion impacts, and medium risk to others when compared to other nonmotorized devices such as individual walkers (high societal value), human-powered bicycles (medium to high risk to others), and equestrians (low societal value). They also suggest what is needed to manage nonmotorized facilities (where SegwayTM HT riders and other users mix), including determining regulations for mixed use, prioritizing users in terms of speed restrictions and yielding hierarchies, and developing education and enforcement policies. While their publication provides an overview of the potential problems associated with SegwayTM HTs in mixed-use settings, it is solely analytical and offers no empirical evidence for the values, impacts, and risks associated with SegwayTM HT use.
Other publications propose empirical research on devices including the SegwayTM HT. Shaheen et al. and Rodier et al. introduced the concept of the SegwayTM HT as a transportation connectivity device.(6,7) They conducted a feasibility analysis and presented a plan for introducing low-speed modes of travel to users of California's Bay Area Rapid Transit (BART) system. They outlined the typical locations and types of crashes that occur for bicycles, scooters, skateboards, and wheelchairs. The authors concluded that, in general, 63 to 80 percent of low-speed crashes involve low-speed devices, and the highest rate of injury is among skateboarders at 2.15 injuries per 10,000 days of use. They concluded that among all of the modes studied, the risk of injury in low-speed travel is slight. While the SegwayTM HT is part of the proposed BART pilot program, no crash or injury statistics from its use were included in the analysis. This is understandable, given the novelty of the device, but it again confirms the need for empirical evaluation.
In an FHWA-sponsored study, Landis and his colleagues provided one of the few empirical analysis research efforts about SegwayTM HT usage.(8,9) They conducted an experimental field study on trail users, including bicycle riders, in-line skaters, people pushing strollers, wheelchair users, SegwayTM HT riders, and others who were videotaped as they rode through a defined course. The researchers reported a comparative outline of pertinent operating statistics such as physical dimensions of the device, turning radius, speed, braking distance, etc. The results of the SegwayTM HT user performance are presented in table 2. Speed was defined as the normal cruising speed of users on a flat, smooth section of a shared-use facility. The perception-reaction time was defined as the duration between the researcher's commencement of the stop signal until the initiation of the braking action by the user. Unfortunately, these findings did not include speed key, which indicates the maximum speed that the SegwayTM HT can achieve. For the i Series, the black key is 6 mi/h (9.7 km/h), the yellow key is 8 mi/h (12.8 km/h), and the red key is 12.5 mi/h (20.1 km/h). Thus, it is unclear what speed keys participants used, making it difficult to assess the braking distance and speed data. However, the overall mean speed would indicate that a large percentage of the riders in the Landis et al. study employed the red key, which was the fastest speed. In addition, navigation around obstacles was not evaluated, and the study did not involve novice users.
1 ft = 0.305 m 1 inch = 25.4 mm * Different than specified by SegwayTM LLC as shown in table 1.
The available empirical research on the SegwayTM HT offers a glimpse into several performance characteristics such as travel speed, turning radius, and braking distance. What is not as understood are the situations that riders frequently face in the real world and how they deal with those situations. To determine the most typical situations encountered by SegwayTM HT riders, a naturalistic review was conducted as a part of the present study. This review looked at the following sources of information:
The review was used to identify the most typical problems encountered in real sidewalk use by SegwayTM HTs. Real sidewalk conditions can be quite complex, and this complexity needs to be reflected in studies of rider performance to determine how the SegwayTM HT maneuvers in naturalistic settings. The present study investigates the behavior of SegwayTM HT riders and their performance in different operational situations.
The research questions addressed in the present study are as follows:
Topics: research, safety, planning, design, roadway safety, pedestrian and bicycle safety
Keywords: research, safety, planning, design, roadway safety, pedestrian and bicycle, controlling shared-use paths and roadways, SegwayTM HT, travel speed, approach speed, stopping distance, clearance distance, operating characteristics, sidewalks, shared-use paths
TRT Terms: research, Safety and security, Safety, Transportation safety