A gadgetbahn is a public transport system based on alternative, unusual or untried technology. Gadgetbahns are usually promoted on the basis that they will be cheaper or better than traditional trains, trams or buses.
The word gadgetbahn was coined in the early 2000’s. It combines the English word ‘gadget’ with the German word ‘bahn’, meaning railway, track, road or path. There is a variety of types of gadgetbahn. Some have real applications, but many are only superficailly attractive.
Could a gadgetbahn cure Bristol’s transport woes quicker and cheaper than buses, trams or trains? What are the options?
Maglev systems use a magnetic field to suspend a vehicle above a track. This means there is no friction other than aerodynamic drag.
Maglev systems can not only reach very high speeds, but they get up to speed very quickly. A Japanese maglev train achieved a record speed of 603 km/h in 2015, on an 18km test track. The speed record for conventional rail, achieved by a French TGV, is 575km/h. But this required 150km of running to get up to speed and slow down, and the record was made on a downhill stretch of line.
Maglev systems are often monorails. Low-speed maglev systems have typically been used for short links to airports or expositions.
Maglev trains have few moving parts. While this reduces maintenance costs, the energy cost of propelling a maglev train is four or five times higher than the cost of running a high speed train. The cost of building the track and supporting infrastructure is also much greater.
Gondolas, or cable cars, are pod-like vehicles suspended from cables which in turn are strung between pylons. Many ski resorts use them. Gondola systems tend to be relatively slow and low-capacity. They can however be useful in mountainous areas where the ground is too steeply graded and uneven for surface systems.
The Clifton Cable Company proposed a gondola lift running from the SS Great Britain to Clifton Suspension Bridge in 2019. A similar previous scheme started at Bristol Temple Meads station.
Neither scheme got off the ground.
In monorail systems the vehicles run astride a single beam. Because the beam has to be quite deep, these systems are usually elevated so that they do not obstruct ground traffic. This adds significantly to the build cost. Because of the complexity of moving the running beam, switching between tracks is generally kept to a minimum
Suspension railways are a form of monorail in which the vehicles hang from an overhead rail. The Wuppertaler Schwebebahn uses this technology, mostly running above the River Wupper in Wuppertal, western Germany.
A guided bus is a bus with a guidance system. This can be guide wheels mounted on the sides of the vehicle, or an electronic or optical system which follows an embedded wire or a painted line.
Bristol has about 2km of kerb-wheel guideway in the Ashton area, used by MetroBus service m2.
The guidance system allows vehicles to pass each other safely on a relatively narrow track. However the track must be built to a high level of precision, which makes it expensive.
Unlike rail vehicles, guided buses can leave the guideway and continue along ordinary roads. Only buses fitted with the guidance system can use the guideway.
Streetcar is the US term for tram, but in Britain it can refer to a bus that is modified to look a bit like a tram. The Belfast Glider is an example of a streetcar. These vehicles may be articulated, and usually have covers over the wheels to give a superficially tram-like appearance.
A hyperloop is a gadgetbahn in which vehicles travel at very high speeds inside a tube or tunnel. The air pressure ahead of the vehicle is lowered to reduce air resistance. Most current proposals are maglev – propelled.
There are no plans to implement a hyperloop system in Britain at the moment.
Autonomous Pod systems
Also known as personal rapid transit (PRT), these systems use small pod vehicles which follow a network of guideways. Passengers are taken non-stop to their destination, by the most direct route.
A few small PRT systems have been built.
By definition these are not mass transit systems, having more in common with driverless cars.
Could a gadgetbahn work in Bristol?
Hyperloop and high-speed maglev systems are for long-distance transport. They couldn’t really be used for local mass transit.
There are places in Bristol where a gondola system could be practical, such as the Avon Gorge. But given the ecological sensitivity of this area, it seems unlikely that it would be permitted.
Other elevated gadgetbahns such as monorails and suspension railways are relatively expensive. A few cities in China, Korea and Japan have invested in multi-line straddle-beam monorails. These systems work in new or rapidly growing cities, but it is hard to see a massive monorail being permitted in historic Bristol or Bath. For similar reasons, it is hard to see how a low-speed maglev system could work, even if an economic case could be made for it.
A streetcar, in the British sense, is just a bus. Buses are essential, and dressing them up as trams doesn’t make them any better or worse. But it can distract attention from higher-quality rail-based alternatives such as trams.
Guided buses are also just buses. The guidance system simply allows segregated busways to be slightly narrower. Only buses with guidance equipment can use them, which makes them more expensive and less flexible than unguided busways. Guided busways prohibit other traffic, but this can be done equally well with a ‘no entry’ sign or a rising bollard.
If autonomous pods or driverless cars were widely adopted, the result would be large numbers of small vehicles making point-to-point journeys. How different would that be from the current congestion caused by private car use?
Bristol, Bath, Gloucester, Cheltenham, Swindon and Weston-super-Mare all had street tramway systems in the past. These integrated with their bus and train services, and provided high-quality electrified services at street level. Modern trams have been proven to work elsewhere, and can work here.
Buses are highly flexible and fill the gaps where trams and heavy rail cannot go. Segregated, unguided busways can help buses get through traffic just as well as more expensive guided systems.
Above all, public transport systems need to be integrated with each other, and with cycling and walking. The main flaw with many gadgetbahns is that they can’t interoperate with conventional, tried-and-tested systems.
Bristol’s biggest underused asset is its suburban rail network. FoSBR’s campaign largely boils down to making much better use of this. Large areas of Greater Bristol could be served by a turn-up-and-go, electrified metro system. The bones of that system already exist.