#movingcity - Open & closed systems: mobility heads down a new track

Where would we be without the train? That old Dutch railway slogan is still as true as ever, at least in densely populated areas. The same goes for the metro, light rail, and trams. The downside of these transport systems is that their success depends on large numbers of people travelling. And if the spatial circumstances change, railway lines can’t easily be rerouted. So how can we design flexible systems that make less of a spatial impact?

The challenge: efficiency vs flexibility

Rail transport is highly efficient. Trains, metros and trams run on frequent schedules and accommodate a large number of passengers at once, as buses do. Moreover, these modes of public transport use separate tracks and lanes that are closed to other traffic, so they’re quicker and safer. Figures from Statistics Netherlands show that the benefits of these so-called closed mobility systems are greatest in and around big cities. In 2019, on average, residents of highly urbanised areas travelled by public transport much more often and over longer distances than residents of nonurban areas.

These closed systems do have significant drawbacks. They are expensive to build, operate and maintain. Hence profitability is greatest in urban areas, where there are more travellers. In addition, the infrastructure can begin to cause problems if it is poorly spatially integrated or becomes outdated over time. Subsequent adaptation is complicated and expensive. Trains, metros and trams, in particular, then, are extremely inflexible as well as being highly efficient. Yet our surroundings need to be adaptable if we are to move with a changing world that requires space for increased densification, the energy transition, and climate adaptation.


The solution: combinations and innovations

If closed systems aren’t the holy grail of mobility, then what might the opposite – open mobility systems – have to offer? Private cars are the most obvious example of an open system. Outside big cities, people are increasingly dependent on cars, as workplaces, social opportunities and services get further away and public transport often fails to provide a good alternative. For travellers, the advantages of the car as an open system are clear. It takes you from door to door, any time you like. For society, the benefits are added flexibility in terms of spatial impact and lower construction and maintenance costs. There are also disadvantages, of course. Open systems have significantly less capacity than closed ones and therefore take up a relatively large amount of space. In previous blogs we discuss the space needed for cars, and parking in particular, in detail.


Open and closed, rural and urban, private and public. While these pairs appear to be opposites, in reality, the best opportunities for future-proof mobility and spatial planning lie somewhere in between. Three recent developments are exceptionally promising in this regard:

1) Expanding closed systems into the wider region

Extending an urban, closed system such as a metro or light rail line to smaller surrounding communities improves accessibility for the city and the region. This type of new metropolitan system is already being explored and applied in various urban areas in the Netherlands. The benefits of a larger-scale closed system can be seen in our study on extending the Noord/Zuidlijn in the Metropolitan Region Amsterdam. If this metro line ran out to the town of Hoofddorp, drivers from outside the city would be able to transfer to public transport more easily and earlier in their journeys. It would help to relieve the growing mobility pressure around Amsterdam and provide an alternative to the busy train service to and from Schiphol Airport.

Another example is the upgrading of the Oude Lijn in the Metropolitan Region Rotterdam-The Hague. This rail link, the first in the Netherlands, originally runs from Rotterdam to Amsterdam and passes through stations including Schiedam, Rijswijk, and Den Haag Laan van NOI. In the coming years, it will be made a quadruple-track line to enable Sprinter trains to run independently of Intercity trains. This will enable more frequent services and the addition of new stations, creating opportunities for new housing near public transport (transit-oriented development). We conducted research with APPM to determine what will need to be done around the stations to create attractive station and residential environments.  

2) Hybrid systems: open/closed and old/new

An example of a system that combines open and closed features is ART: Autonomous Rail Rapid Transit. This system is already in use in cities in China and elsewhere. ART’s self-driving electric vehicles are a blend of train, tram and bus. Rather than running on rails, they travel on rubber wheels along a dotted line on the road with the aid of sensors and a multiaxle steering system. So repositioning a route is no problem.

Hybrid solutions can involve old as well as new types of closed systems, as we found in a study conducted with Goudappel on accessibility between the Breda, Gorinchem and Utrecht regions. There is no high-quality public transport link between these towns to provide a supplement and alternative to the busy A27 motorway. The proposed solution is to build a smart bus link, with a high-quality zero-emissions vehicle running in an obstacle-free lane between Breda and Utrecht at 120 km/h. As a dedicated lane would currently require excessive adaptation and investment, we analysed an alternative model involving an easier-to-implement 80 km/h version.

Open systems can be used in different ways outside and inside cities. For example, multiple vehicles from outside an urban area could be brought together at the edge of town and then be routed along bus lanes to function as a closed system. In this model, smaller vehicles form a whole in densely populated areas. This idea was explored in the Future Prospects for Primary Networks project. The advantage is that less busy routes can be served by smaller vehicles that come together to form a larger “vehicle” as needed. Such a system would also require little infrastructural intervention, meaning routes could easily be altered.


3)      Innovations in the mobility field


Autonomous public transport options that combine the benefits of open and closed systems present abundant opportunities. For example, in The Hague, a driverless shuttle bus runs between a city bus stop and the entrance to the HagaZiekenhuis hospital, making the premises more accessible. Private autonomous transport also affords plenty of possibilities. Self-driving cars give users the benefits of private transport but take up less space when coordinated to travel in a train, increasing capacity on a particular route. Drivers become passengers and can use the journey time to do something else. 

For added gains, technology can be deployed along with smart modes of transport to enable new ways of using them. The Arriva Vlinder is a good example. This on-demand service is available in a number of areas in eastern Gelderland province. The Vlinder minibus supplements the regular timetable, for example in the evenings. Passengers use an app to reserve a seat and choose the stops where they want to begin and end their journey. This solution, too, combines the benefits of an open system (because of its flexibility) with those of a closed system (because of its greater capacity). As the technology develops, it could lead to the elimination of regular stops and routes, with the service customised for to the riders who are on the bus at any given time.


The need to make room for transitions is putting extra pressure on the Netherlands’ already limited space. Investment in fast, high-quality public transport solutions will do a great deal to make travel more efficient and less space-consuming. As an added benefit, it will open up opportunities for new housing and densification, specifically around stations. Meanwhile, creative combinations of different modes and manners of travel are arising out of open and closed systems. These combine the best of both worlds while lessening the pressure on available space. This development, along with recent technological advances, raises the question of how long, and where, investment in railway lines will be warranted. After all, it is clear that plenty of flexible solutions can be found that will suit the future spatial context.


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