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Segway PT

The Segway PT is a two-wheeled, self-balancing electric vehicle invented by Dean Kamen. It is produced by Segway Inc. of New Hampshire, USA. The name "Segway" is a homophone of "segue" (a smooth transition, literally Italian for "follows"). PT is an initialism for personal transporter while the old suffix HT was an initialism for human transporter.

Computers and motors in the base of the device keep the Segway PT upright when powered on with balancing enabled. Users lean forward to go forward, lean back to go backward, and turn by using a "Lean Steer" handlebar, leaning it left or right. Segway PTs are driven by electric motors at up to . Gyroscopic sensors are used to detect tilting of the device which indicates a departure from perfect balance. Motors driving the wheels are commanded as needed to bring the PT back into balance.

The limited capabilities compared to vehicles of similar price have limited Segway market penetration by the general population. Segways have had success in niche markets such as transportation for police departments, military bases, warehouses, corporate campuses or industrial sites. The legal road worthiness of the Segway varies with different jurisdictions' classification of the device as a motor vehicle.


The Segway PT has been known by the names Ginger and IT in the past. The name Ginger followed the name of the project the Segway branched from: the inspiration behind the Segway PT came from the balancing technology of Kamen's innovative wheelchair, the iBOT, a wheelchair which can climb stairs, and prop itself up to balance on two wheels, thus raising the user up to an eye-level position. The first iterations of balancing technology were done in early Segway models. It was called Fred Upstairs after Fred Astaire — hence Ginger after Astaire's regular feature film partner, Ginger Rogers. The invention, development, and financing of the Segway was the subject of a narrative nonfiction book, Code Name Ginger (in paperback as Reinventing the Wheel), by journalist Steve Kemper; its leak was what led to the rampant and hyperbolic speculation on the internet about the "IT" device prior to its release.

The speculation generated on the internet created an unexpected advance buzz about the then-unknown product that was, at times, hyperbolic. Steve Jobs claimed that it would be "as big a deal as the PC, but also that "I think [the design] sucks. Its shape is not innovative, it's not elegant and it doesn't feel anthropomorphic. Articles were written in major publications speculating on it being a Stirling engine or antigravity device. The product was unveiled December 3, 2001 on the ABC News morning program Good Morning America.


In September 2003 the Segway PT was "recalled" so a new software patch could be applied. This was because if users ignored repeated low battery warnings on the PTs, it could ultimately lead them to fall. With a new software patch to version 12.0, the PT would automatically slow down and stop in response to detecting that the battery's power capability is low, and specifically and more aggressively require a rider to dismount safely.

In August 2006, Segway discontinued all previous models and announced new second generation designs that upgraded many elements of the previous transporters. The Gen II PT, marketed under the two product lines, i2 and x2, allows users to steer by leaning the handlebars to the right or left, which matches the intuitive nature of leaning forward and backward to accelerate and decelerate. Another feature is wireless InfoKey access.

In September 2006, all 23,500 of the vehicles were voluntarily recalled so a new software patch could be applied to the operating system. An extremely rare software bug could be triggered if a rider were to jump up and down several times at full speed. This bug could cause a rearward torque to be suddenly applied to the wheels, throwing off its rider. Segway released a patch to its software (version 14.2) to resolve the problem.


In 2003 the company sold 6,000 units, and by September 2006 approximately 23,500 had been sold. In May 2006, Segway Inc. reported that the city of Chicago had signed a five-year, $580,000 contract to purchase up to 100 Segway GTs, associated accessories, replacement parts and service, for use in several city departments, including Police, Fire, Airport Operations and Emergency Management. It was the largest municipal contract the company had signed.


The dynamics of the Segway PT are identical to a classic control problem, the inverted pendulum. The Segway PT has electric motors powered by Valence Technology phosphate-based lithium-ion batteries which can be charged from household current. It balances with the help of dual computers running proprietary software, two tilt sensors, and five gyroscopes. (The gyroscopes do not affect the balance; they are merely used as sensors.) The servo drive motors rotate the wheels forwards or backwards as needed for balance or propulsion. The rider accelerates or decelerates by leaning forward or backwards in the direction he or she wishes to travel. On older models, steering is controlled by a twist grip on the left handlebar, which simply varies the speeds between the two motors, rotating the Segway PT (a decrease in the speed of the left wheel would turn the Segway PT to the left). Newer models enable the use of "leaning" to steer as well as move forwards or backwards.

The Segway PT is built simply to stay balanced in one place. Designed to mirror the process of human walking, if the rider standing on an initially balanced Segway PT leans forward, therefore offsetting the balance, the PT moves forward to regain balance just as in walking a leg moves forward to retain balance. With the Segway PT, changes from a balanced status are first detected by the gyroscopes, and signals are passed on to the onboard computers which then direct motors to regain balance. This process occurs about 100 times per second, so small adjustments to maintain balance occur almost immediately after the balance is offset by the rider.

The side effect of this balancing system is that as the Segway PT balances itself the entire unit changes position in the direction it has moved to restore balance. (For example, if the rider leans forward, the entire Segway PT will move forward from its original position, until the rider restores an upright position on the unit.) This is precisely how the Segway PT is controlled - the balancing and movement is essentially one combined system.

The Segway PT features a governor (speed limiting) mechanism. When the Segway PT approaches the maximum speed allowed by the software, it intentionally begins to tilt slightly backwards. This moves the platform out in front, and leans the handlebars backwards towards the rider, eventually nudging the rider to lean back slightly and slow the Segway PT down. If not for the governor, riders would be able to lean farther than the motor could ever compensate for. The Segway PT also slows or stops immediately if the handlebar of the unit (or forward bag) nudges into any obstacle.


Because the Segway can reach speeds over , the Bicycle Helmet Safety Institute recommends that all riders wear helmets when using Segways. The US Consumer Product Safety Commission doesn't have Segway specific recommendations but does say that bicycle helmets are adequate for "low speed, motor assisted" scooters.

Segways perform best in areas with adequate sidewalks, curb cuts at intersections, and ramps.

They are used in some theme parks by visitors and employees. Angel Island State Park in San Francisco Bay in California, offers Segway tours, but prohibits personal Segways except as needed by disabled visitors.

Though a Segway-focussed organization, Disability Rights Advocates for Technology advocates for Segway PT sidewalk and facility access as an ADA issue, Segways cannot be marketed in the US as medical devices: they have not been approved by the Food and Drug Administration as a medical device, and Johnson & Johnson claim exclusive rights to the medical uses of the balancing technology found in the iBOT and Segway.


Previous versions included (in order of release):

  • Segway i167 - Titanium color base. One of the first two Segway HTs released.
  • Segway e167 - The same as the i167, but with the Electronic Kickstand (allowing the HT to stay balanced without a rider). The e167 also came standard with the upper and lower cargo structures.
  • Segway p133 — Human Transporter - Smaller platform and wheels and less powerful motors than the i and e Series. Top speed was 4.5 m/s in the p-Series.
  • Segway i170 - Midnight Blue color base. Otherwise, the same as the i167.
  • Segway i180 - Available with Sport Red, Solar Yellow, and Midnight Blue colored fenders. Optional Saphion Lithium-ion batteries
  • Segway XT - The first Segway HT designed specifically for recreation.

The Segway's i-Series model's maximum speed is 12.5 mph (approximately 20 km/h). Maximum power is 2 horsepower (1500 watts) per servo motor. The i-Series is capable of covering 15–25 miles (25–40 km) on a fully charged lithium ion battery, depending on terrain, riding style, and the condition of the batteries. It takes 8-10 hours to complete a full balancing and recharging cycle. For each 15 minutes of time re-charging, the batteries regain a mile of charge. The batteries also recharge while riding downhill and stopping, and by the Segway being pushed while turned off. The p-Series is capable of covering 6–10 miles (10–16 km) on a fully charged nickel metal hydride (NiMH) battery, depending on terrain. It takes 4–6 hours to recharge, and regains 1 mile for every 30 minutes charging.

In 2006, series i2 and x2, were released, replacing the older lineup:

  • i2: Uses the new LeanSteer and InfoKey technologies.
  • x2: The new XT model, same upgrades, with its own special software for off-road use. Can be equipped with a golf bag carrier, replacing the GT model. Turf Tires Available.

Specialized variants of the i2 are sold under different names like:

  • Segway GT — Golf Transporter
  • Segway PT i2 Ferrari Edition

The newer models i2 and x2 weigh 105 lb and 120 lb (48 and 54 kg) respectively.

In May 2008, Segway introduced a new "Metallic Sage" color for the i2 model, in addition to the original white and black colors available.


The original Segway models were activated using one of three keys:

  • Black Key — for beginners. Slowest speed (electronically limited to no more than 6 mph); slower turning rate.
  • Yellow Key — for intermediate users and/or pavements. Faster speed-up to 8 mph; faster turning rate.
  • Red Key — for more advanced users in open areas. Maximum speed-up to 10 mph on p-Series and 12.5 mph on i-Series; and max turning rate.

For the new i2 and x2, an InfoKey is used to control settings. The Infokey can turn on the PT from up to 15 feet away, as well as turn on beginner mode (the equivalent of the old Black Key) or advanced mode (the equivalent of the Red Key), show mileage and a trip odometer, as well as put the Segway into Security mode, which locks the wheels and will set off an alarm if moved.

Restrictions on use


In Australia laws are determined at the State level, each differing in their adoption of the Australian Road Rules. In New South Wales, the Segway has been confirmed by the Roads and Traffic Authority as being illegal on both roads and footpaths. "In simple terms, riders are way too exposed to mix with general traffic on a road and too fast, heavy and consequently dangerous to other users on footpaths or cycle paths.


The special police forces trained to protect the public during the 2008 Summer Olympics use the Segway for mobility.


In April 2008, the Dutch Government announced that it would ease the ban it had imposed in January 2007 that made it illegal to use a Segway on public roads in the Netherlands. Until recently, a tolerance policy was in place due to the inability of the authorities to classify the Segway as a vehicle. However, certain handicapped people, primarily heart and lung patients, are allowed to use the Segway, but only on pavement. From July 1 2008 anyone over the age of 16 is permitted to use a Segway on Dutch roads but users need to buy custom insurance. Amsterdam police officers are testing the Segway.

It is unlawful to use a Segway on any public road or pavement in Sweden.

In the United Kingdom, the Segway is classified as a powered vehicle and subject to Road Traffic law, with the effect that it is unlawful to use a Segway anywhere other than on private property with the owner's permission. Britain's two largest opposition political parties, the Conservatives and Liberal Democrats, have lobbied the Government to change the law to allow Segways to use public cycle lanes.

In Denmark the Segway is classified as a moped. As such vehicles are required to be fitted with lights, license plates and mechanical brakes, the Segway is effectively banned it from public roads.

In Germany the use of a Segway is only allowed on private grounds except for some city tours that require a special permit. On 25 April 2007 the use of a Segway on public bicycle paths, sidewalks and roads within city limits was allowed in the state of Saarland after local police tested it.

In Switzerland the Segway is classified as a light motorcycle. Only the PT i2 has been approved for use in Switzerland. The PT i2 may be used on roads provided that it is equipped with a Swiss Road Kit and a license plate. The Swiss Road Kit has front and back lighting, a battery source, and a license plate holder. Use on sidewalks and pedestrian zones is prohibited. An exception is made for handicapped individuals who must obtain in advance a special authorization from the Swiss Federal Roads Office. The Segway PT i180 may also be registered for use on specific request. However, the PT i180 must be equipped with a left/right turn indicator system before it may be admitted for road use.


In Japan, the Segway is treated as a motorcycle with an engine displacement between 50 cc and 125 cc. As such, the vehicle must be equipped with brakes and signal lights, and must register for a license plate, making it virtually impossible to lawfully use a Segway on public roads.

United States

The company has challenged bans and sought exemption from pavement restrictions in over 30 states. The Segway PT has been banned from use on sidewalks and in public transportation in a few municipalities, often because it is not classified as a medical device. Advocacy groups for pedestrians and the blind in the US have been critical of Segway PT use: America Walks and the American Council of the Blind oppose allowing the PT to be driven on sidewalks, even for those with disabilities, and have actively lobbied against any such legislation.

In November 2002, before it was widely available, the city of San Francisco banned the Segway PT from sidewalks citing safety concerns. However, a number of Segway Tour operations use them anyway. Handicapped individuals may use the Segway PT on sidewalks in San Francisco in compliance with Title II of the Americans with Disabilities Act.

In February 2004, Disney banned Segway PTs from its theme parks, stating they had not been approved by the FDA as medical devices. In the same month, Disney began offering Segway tours of its Epcot theme park. In early August 2007, Disney began offering a similar guided tour in its Disney's California Adventure park in California.


In the US the price (MSRP, July 2008) of the various Segway models ranges from $5,350 to $6,400.

In the UK the prices are around £4,399 to £4,599 excluding delivery costs.

In France a Segway sells at between 6400€ and 7200€. Their legal status is still uncertain.

Segways can be rented in some American and European cities for around €70 ($110 USD) per day.


When it was launched in December 2001 the annual sales target was 40,000 units, and the company expected to sell 50,000 to 100,000 units in the first 13 months. Segway Inc's investors were optimistic. Inventor Dean Kamen predicted that the Segway "will be to the car what the car was to the horse and buggy" and John Doerr, a venture capitalist who invested in the company, predicted that Segway Inc would be the fastest company to reach $1 billion in sales. In fact only about 30,000 Segways were sold from 2001 to 2007.

Critics point to Segway Inc's silence over its financial performance as an indication that the company is still not profitable, as about $100 million was spent developing the Segway.

See also


Valence to develop batteries for Segway transporters

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