Cable car gondolas travel above a city

Researchers develop new transport systems

forschung leben – the Magazine of the University of Stuttgart

The Stuttgart logistics model is rethinking transport and storage processes for the future, including through the use of roller coasters and cable cars. The idea is to save our cities from gridlock.
[Photo: Doppelmayr]

The retail world is changing, partially because customers are demanding more and more bespoke products. "This presents a huge logistical challenge,” explains Prof. Robert Schulz, head of the University of Stuttgart’s Institute of Mechanical Handling and Logistics (IFT), “because components have to be delivered in increasingly smaller quantities." This was one of the reasons for developing the Stuttgart logistics model. "Second, living spaces, especially cities are also changing. We need to find solutions to avoid drowning in a sea of traffic."

Prof. Robert Schulz in the IFT’s cableengineering room

The model is, therefore, intended to point out approaches to organizing supply and disposal in cities in an environmentally friendly and CO2-neutral manner. It also makes use of existing technical solutions. The guiding principles of the Stuttgart logistics model are to rethink processes and to use these solutions. 

What is already becoming apparent is how goods transportation is set to change in future: goods will be transported from large logistics centers close to major conurbations to small urban distribution stations, from which they will be transported to the customer over the last mile. Express parcel delivery service providers are already starting to implement this concept, says Schulz.

DHL, UPS, DPD and Co. all drive their delivery vehicles through the same streets: one has to question the sense of this

Prof. Robert Schulz, Head of Institute of Mechanical Handling and Logistics

"DHL, UPS, DPD and Co. all drive their delivery vehicles through the same streets: one has to question the sense of this." He assumes that the political efforts to bring about a traffic transition in cities will also free up parking space. "These spaces could be used for micro-hubs." Parcel delivery service providers could then use cargo bicycles or other emission-free vehicles to transport parcels to the customers from these centers or, alternatively, the customers could collect their goods from there.

Flexible transport systems are necessary

The trend towards personalized products is raising further questions according to the logistics researcher: "Why does the entire production process have to take place at the manufacturer's premises? Why not move it closer to the customer?” Particularly goods that are localized for different countries, he goes on, are already being processed in the logistics companies’ distribution centers, where as Schulz says, clothing labels and emblems are applied. At the same time, 3D printing is becoming more important as a production technology and will change production chains. "Rather than first delivering all components to a central factory and then distributing them to customers certain production process will be transferred to the logistics centers in future." 

This will create new intralogistics tasks: "These logistics centers will then receive a wide variety of products from different manufacturers within a very short space of time, which they will then have to distribute, sort, configure and pick or else individualize according to customer orders," Schulz explains. These tasks cannot be done using rigid conveyor belt systems. "It requires extreme flexibility." That is why the use of driverless transport systems, which have primarily been used in industry up to now, is likely to increase. The team at the IFT is currently looking into how these transporters could move freely within a given space and still reach their destination precisely. Among other things, they are collaborating with a start-up on an interior navigation system that uses a special radio technology. 

40,000 truck journeys per year between Nußlochand Leimen in Baden-Württembergwill be saved by HeidelbergCement’s local freight cable car system.

According to the Stuttgart logistics model, when the goods leave the logistics center, they would be transported to the micro-hubs using the aforementioned technical solutions. This could be done, inter alia, by using the High-Velocity Transport System (HVTS) developed at the Institute. The idea for the HVTS is inspired by the traditional roller coaster, but the gravity-based drive system was changed. The IFT team developed a new drive type: the rail has been rotated through 90 degrees and each car has its own electric motor. As Schultz explains, the team had to solve one particular challenge presented by this technology: "the flank distance between the gears changes in a curve or on a slope. A constructive development is required to ensure that this gap remains the same."

The roller coaster as inspiration

The principle has already been implemented several times for leisure roller coasters, such as the "Sky Dragster" in Bad Wörishofen, Bavaria among others, in collaboration with a manufacturer. The aspiration is to use this new drive concept to transport goods and merchandise. As a logistics system, the HVTS needs to be able to transport loads of up to 1500 kilograms on standard EUR-pallets at 50 to 60 kilometers per hour and to overcome inclines of up to 45 degrees. It could, for example, also operate underground in existing sewers to provide a link between logistics centers and distribution stations. The HVTS could also deliver goods to large production facilities such as car factories and their supplier parks. However, the researchers are still in the process of developing a track system that requires less material and costs less than the steel double tracks used by roller coasters.

Cable cars on the foremarch

So, Schulz has another promising means of transport in mind: the cable car. Scientists at the IFT have been researching cable technology for decades and testing cable car routes all over the world. "Cable cars would be an interesting way to link the micro-hubs with the suburban logistics centers,” he muses: I could combine the two: every third gondola would transport goods thus reducing road transport.” The others, he goes on, would then be available for local public transport. "Whenever the question of how to reduce traffic congestion in cities is brought up, you're always straight back to public transport," says the logistics expert. "The cable car could play a major role in this context in the future."

Cable cars as an alternative urban transport mode are increasingly coming into focus. The Institute for Mechanical Handling and Logistics (IFT) is currently developing appropriate planning tools together with the engineering firm "SSP Consult Beratende Ingenieure GmbH". The Deutsche Bundesstiftung Umwelt (DBU) is supporting the two-year project technically and financially with around 300,700 euros.

Cable car in Bolivia

A good example of this is the city of La Paz in Bolivia where ten Mi Teleférico cable car routes have been in operation since 2014. More and more German cities, including Munich and Stuttgart, are also considering cable cars as a mode of transport. "Unfortunately, this has always failed so far, partially because urban cable cars are associated with tourist locations," says Schulz. However, "the crucial thing is to integrate them into the public transport system to benefit the passengers."

Another aspect of cable cars is also difficult: "As soon as you wanted to erect a support structure here in Stuttgart, you’d meet with opposition from a relatively high number of people," Schulz fears. Nevertheless, there is a lot to be said for the cable car with it’s quiet operation and unchanging drivetrain hum, practically no waiting times and: "compared with other rail systems, it is definitely the cheaper solution for the same performance."

Tourist cable car in Koblenz

It requires no expensive tunneling, unlike a subway. By contrast with trams and suburban trains, they require hardly any space, and don’t seal over much surface space. Cable cars are also largely self-sufficient, which reduces personnel and operating costs. But, as Schulz emphasizes, the acceptance problems are definitely there and need to be resolved: "nobody wants a cable car going over their residential area." So, how and where these cable cars could become established is another question that the research team wants to answer in a research project in the coming years. 

Editor: Daniel Völpel



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