Dualmode System Implementation in Big Cities


Palle R Jensen

It may be a wise strategy to try implementing a new system as a system to connect two cities with attractive Public Transport based upon larger dualmode vehicles such as maxi-ruf (see: www.ruf.dk/maxi) and smaller public ruf cars.

On the other hand, the real problems are to be found inside the cities, so the target must be to solve these problems.

A lot of difficulties arise from trying to introduce a new system in an existing city. This is true for well-known systems as well as for new systems. The well-known systems, roads and rail, take up a lot of expensive space. Newer systems such as the RUF system use less space, but must face the problem of being unusual.

Here an intercity system implementation can be of help. People get time to get used to the system. They can see it running and try the feeling of "riding" a monorail. They will find that the view is excellent and the ride is smooth. If this system uses off-line stations, the users will experience much shorter travel times than for traditional public transport and much more frequent service (potentially on-demand). The average speed will be higher than the speed of cars on an uncongested highway.

After some time people will want to be "connected", meaning that the rail starts nearer to them. The guideway system will grow to become the final network covering the city with a mesh size of approximately 3 x 3 miles.

Which are the problems and how can they be solved?

1. Right Of Way

It is not easy to find ROW inside an existing city. If a new road or a new rail line is created, the ground has to be cleared and leveled. A rail line demands very precise leveling and a road lane requires 3 m width in order to get a capacity of 2000 cars per hour per direction.

A system like RUF, which uses a guideway to carry the vehicles, has a lot of advantages compared to the traditional systems:

No leveling is required, only foundations for masts separated by 20 m. The length of the masts can compensate for the variations in ground level. It is not a major problem to place a RUF rail on a hillside.

Guideway dimensions are very small (85 cm x 58 cm) for the triangular RUF guideway. The guideway plus vehicles requires 2.5 x 2.5 m of free space.

Steep grades can be tolerated. Because of the special drive system of RUF, vehicles can climb steep grades (e.g. 20%).

These and other advantages make it possible to put up a RUF rail in places where it would be difficult to place other systems.

If, for instance, you want to supply a capacity of 3.600 vehicles per hour per direction along a water channel in Los Angeles you could do it with a RUF rail taking up only 5 m in width while a road would require 4 lanes, or more than 12 meters in width. The road would cost a lot because a lot of installations and buildings would have to be removed. The RUF guideway can be placed along the side of the channel. See www.ruf.dk/solutions

Old railroad lines can be used as well as medians of freeways. On the other hand, it might be better to create the new system as a network which is complementary to the existing freeway network. This means that the access/egress points will not coincide with the access/egress points of the freeway. In this way, the possible congestion problems at access/egress points will be minimized. See www.ruf.dk/network

2. Stations or junctions

A network of guideways means that there have to be junctions where vehicles can enter/leave or change direction.

If you are talking about roads, these structures take up huge areas. This is because the roads are wide compared to the capacity provided and because the curves are negotiated at relatively high speed.

A RUF junction can be more compact since the speed profile of a RUF network is such that the top speed is 95 mph while the junction speed is 20 mph. This means that very narrow curves can be used for turning vehicles (e.g. a 26 m radius of curvature). A high capacity (3.600 ruf/hour/dir) junction can be placed above existing road space if the road has a total width of 40 m. (which is not uncommon in the U.S.

Stations for public vehicles (maxi-ruf) can be placed off-line in a system where switching is easy. Sometimes the best place for a station may be at some distance from the main line. It this case, a feeder line can be used in order to get closer to a Major Activity Center.

3. Visual impact

Elevated systems are still unusual, but more and more cities will accept them because they can supply new capacity to a transport system without interfering with the cars on the roads below.

One of places in the world where people are used to elevated systems is in Seattle where an elevated  monorail has been running since 1962. It has become quite popular and the people of Seattle have recently voted for an substantially expanded monorail system. Planning for this elevated system is currently underway.   The visual impact of the existing monorail is much greater than it would be for a   monorail system like RUF as its guideway is much more slender.

When a monorail is erected in an existing street, it is possible to improve the visual appearance of the road space by integrating many of the poles and wires into the monorail gudeway so that they disappear visually.

Much can be done with trees in order to cover the rail if needed. Another approach is to make a virtue of necessity and let architects compete to design the best possible appearance of the guideway and the masts (see www.ruf.dk/guideway).


It seems to me that there are a number of possibilities available to help overcome the difficulties that will be encountered when trying to implement a Dualmode system within cities. Since cities clearly have the biggest transport problems, solutions for these problems should have the highest possible priority.

Let me finish by quoting what was written in the magazine New Scientist on April 24. 1999, page 51, about the RUF system:

" – an innovative system such as Jensen’s could transform cities"


Last modified: July 26, 2001