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August 10, 2012

Technical Details of the Shweeb human powered monorail

Shweeb is an innovative integration of two existing technologies - the monorail and the recumbent bicycle.

With the use of new technologies, interest in the next generation of small scale monorails (Personal Rapid Transport - PRT) has begun to resurge with the construction of a new, driverless system to replace bus transport at Heathrow Airport.

Recumbent cycles have made great advances in the last decade primarily due to improved comfort, greater efficiency, higher speeds and no carbon emissions. However, the low aerodynamic profile does create significant issues as they are too low to be clearly visible by other road users, their riders have poor visibility, and a modest side wind will destabilise and topple an velomobile. These issues have severely inhibited the adoption of HPVs in urban environments.

Google (project 10 to the 100) allocated $1 million to fund research and development to test Shweeb’s technology for an urban setting.




FAQ Highlights

1. I’ve seen the video of Shweeb in action and it looks like hard work – is it?

The video shows our prototype Shweeb in Rotorua, New Zealand, where it is used as a velodrome racetrack. Naturally, riders want to achieve the fastest speed they possibly can in an effort to beat their competitors and try to get their name on the record board. Riders have achieved speeds of over 50km/h on this tight track, but on a longer, straighter track they should be able to achieve 70km/h (that's faster than an Olympic cyclist!) The point is that the Shweeb is extremely efficient.

On firm, flat ground, a 70kg man requires about 100 watts to walk at 5km/h. The power required to move a Shweeb along a rail at 20km/h is only 33 watts.

2. It may be efficient, but is it practical?

2a. What if I want to overtake?

Firstly, let's assume we are talking about Shweeb in its capacity as a transport system: The pods are geared so that the maximum achievable speed is limited to about 25km/h. This is very easy pedalling (even for someone relatively out of shape), so we expect that a Shweeb transport system would maintain a constant speed.

2b. But what if someone refuses to pedal or goes really slowly?

Impact-cushioning buffers at each end of the pods allow faster pods to run into slower pods and form a Shweeb ‘peloton’. This increases aerodynamic efficiency and, unlike a bicycle peloton, the power produced by those behind can contribute to the overall power of the group, thereby increasing speed and efficiency and removing the need to overtake. Should the rider in front refuse to pedal, the extra effort required by the rider(s) behind is minimal due to the low rolling resistance and single aero-pressure point of the peloton.

3. What kind of capacity can a Shweeb system handle?

A Shweeb track can handle high capacity due to two key factors: Firstly, stations are off-line meaning that, when someone wants to stop, they can switch off the main line and go into a station without affecting anyone else. As such the mainline is always moving at the desired speed. Secondly, unlike road transport, Shweeb pods require no stopping distance between them so can travel back to back. In theory, a single rail could move 10,000 people through a 1m2 airspace.

But obviously capacity is restricted by station throughput. Where maximum capacity is required, pods will be released from a station in groups (or 'pelotons'). A station can have any number of embarkation pods awaiting riders, depending on the length (and number of) platform(s). Given that it takes about 30 seconds for someone to board a Shweeb, a station with one platform of 10 pod lengths could release 10 pods every 30 seconds. This equates to 1,200 per hour on a single line going in one direction.

What's the Shweeb like to ride?


Is it comfortable?
Yes! The fully adjustable seat is reclined at 20 degrees. This spreads the rider's weight over a large area, takes pressure off the spine and is as comfortable as a deck chair. It also reduces any risk of vertigo anxiety as the rider has no balance issues and feels well supported. Light padding on the seat provides extra comfort whilst providing a firm platform to push back against the seat when pedalling.


4a. Doesn't it get hot and sweaty in the pod?
Ventilation holes and a sun reflecting roof help to keep temperatures moderate inside the pod. Riding a Shweeb at 20km/h requires less energy than walking at an average pace, so there is no reason why one would work up a sweat.

4b. How do you keep the pods clean?
Pods are aired and disinfected after each ride. Wipe-clean surfaces and excellent ventilation keep the pods hygienic and easy to maintain.

4c. What if I want to travel with someone else?
We are developing 2-seater pods where a passenger sits behind the rider. This is particularly useful for carrying children or disabled people. Equally, groups can travel together in a train of pods, and an intercom system could enable communication between them.

4d. Don't you think people wearing skirts or kilts might be concerned about privacy / dignity?
We would suggest wearing shorts or trousers for most comfort and peace of mind! In future, pods may have one-way tinted windows so one can see out but not in - this would address the issue directly.

5. Who can ride a Shweeb?

5a. Can disabled people ride it?

There are a few options for people who are unable to pedal themselves:

i. Sit in a standard pod and be escorted along the track by a pod behind.
ii. Sit as a passenger in a 2-seater pod.
iii. Shweeb can design hand-powered and/or electric-assisted (or fully powered) pods.

We have also had a number of blind people ride the Shweeb in Rotorua. The Shweeb offers them the unique opportunity to take control of and power a vehicle themselves.


5b. How do unfit or overweight people manage?

If you can walk, you can Shweeb! There is no weight limit to ride a Shweeb. Anyone who can fit in a train, aeroplane or bus seat will be able to fit in a Shweeb pod.


5c. How do you manage people of totally different heights using the pods one after the other?

5d. The seats quickly adjust to take riders between 1.2m and 2.2m. An easy seat slide mechanism sets the seat at the perfect length for each rider.

Aerodynamics and Efficiency
There are two ways a vehicle can attain speed. One is to fit the vehicle with a bigger engine to burn more fuel. The other is to reduce the resistances acting against the vehicle. The Shweeb proves that by intelligently removing resistances, the energy required to move a vehicle becomes very small. So small in fact that it becomes possible to dispense with the mechanical engine and utilise the organic engine that the human passenger already carries - muscle power.

The three main resistances acting against any moving vehicle are aerodynamic drag, rolling resistance, and transmission losses. At high speeds, aerodynamic drag is by far the greatest. Around 80% of a cyclist’s energy is used to overcome wind resistance. By placing the rider feet forward, recumbent cycles halve the amount of wind resistance. Adding a fairing allows it to slip through the air even more cleanly. All world cycling records are held by fully-faired recumbent cycles, which have been ridden at speeds over 90kph (56mph).

Furthermore, by running hard wheels on hard rail, the Shweeb greatly reduces rolling resistance. Its specialised transmission system transfers power from the pedal to the rail with minimal friction losses.

The Shweeb requires less energy to cover a given distance than any other vehicle on earth.

On top of this, Shweebs travelling in trains are even more efficient. The leading pod pushes the air out of the way, allowing the following riders to combine their strength and push the leading rider forward at a speed beyond that which any rider could manage individually. The single high pressure zone at the front is effectively shared over the total number of riders in the train.

Towers and Spans



The Shweeb glides through the city on sleek ultra-thin rails measuring only 200mm x 200mm (8 inches) and spanning 20m (66ft). These are set 6m (19ft) above ground level to clear traffic and pedestrians. They can be styled and coloured to suit with the surroundings.

Buffers and Trains



There is no need for an overtaking lane. When two riders come together, the dynamics change completely. Riders travelling separately are held back by the high pressure zone (the ‘headwind’) pushing against their nose, and the low pressure zone (the vacuum) pulling on their tail. When vehicles come together, these resistances are halved. The front rider loses their vacuum and the rear rider loses their headwind. In effect they become one vehicle with two engines. The front rider simply changes up a gear to compensate for the higher speed.

Just as tandem bicycles always travel faster than two single bicycles, two Shweebs travelling in a train always travel faster than either of them could travelling solo.

It is for this reason that the bullet shape is most efficient. Although an aerofoil (‘teardrop’) shape would be faster for a solo rider, its reduction of tail vacuum makes it less effective as a train segment.

Stations and Stocking

The station, in its simplest form, is a sheltered platform where riders can get on and off the pods. Empty pods are sanitised and rotated on a storage track. The supply of pods is carefully managed to serve the customers’ movements. In the morning rush hour, as commuters migrate from their residential towers to the central business district, the supply of spare pods at residential stations is depleted while at the downtown end, a surplus forms. To maintain a balanced supply, the network staff transport the empty pods back to the residential areas. This is possible because a single staff member can move multiple pods. In the evening the flow reverses.

The station measures only the size of five standard car parking spaces yet has the capacity to release 360 commuters an hour onto the main line.

Different Pods

The standard commuter pod has space for a backpack/briefcase and a coat hanger for your jacket. A child seat can be inserted too. If there are two of you, double pods are available.

Bridges and Suspension Spans

Cables are a more effective way to span longer distances. The ‘dead load’ of a road bridge is many times greater than the live load. A car travelling over a bridge only uses a fraction of the surface area of the bridge, but the lane must be three meters wide and able to carry heavy loads on any part of it. On a Shweeb bridge there is very little dead weight because the pods follow a predictable track and weigh a set amount. The 200mm wide rail weighs less than the pods travelling along it.

Sustainability

The Shweeb is a zero-emission transportation system. Because it is so easy to pedal, the rider will not even emit much more carbon dioxide than he/she would if using a more passive transportation mode

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