Palle R Jensen
RUF International
Roedovre Centrum 155
2610 Roedovre, Denmark
Telephone: (+45) 3670 8895
Fax: (+45) 3670 8866
E-mail: PRJ@RUF.DK



Dual-Mode Technology - The Third Alternative ?

Until now, policy makers have been focusing on the two old sectors within transportation:
Automobiles and Public Transportation.
It is very difficult within this frame to create sustainable development and maintain
Fortunately, a new sector is currently being developed: Dual-Mode transportation systems.
Combining car mobility with train sustainability is possible with this new and very
attractive development.
The paper will present the principles of Dual-Mode transportation, exemplified with the
Danish RUF system.

Current Trends In The Major Cities Of The World:

All big cities are growing

There seem to be no way of preventing the big cities from becoming even bigger in the future. Young people from the countryside are attracted by the varied opportunities that city life can offer. The result is that the traffic demand across any cross section within the city is increasing.

The structure of the cities is changing

People prefer to live in suburban areas instead of in dense parts of the cities. It is more peaceful and the level of pollution and noise is much lower than in the dense parts of the city.

The traditional Central Business District is becoming less important and new suburban centers are created.

The traffic habits are changing

The traditional family pattern is changing. Previously, the wife stayed at home taking care of the children. Now she is often working and the children are placed in some kind of child care center. Shopping is often done at big shopping centers attracting customers from remote areas.

All these factors contribute to an increasing amount of transportation within the cities. The traffic pattern is very diffuse in time and space.

The pace of modern life is faster than ever

The modern family seems to be more actively involved in activities outside the home than ever before. The time schedule of a modern citizen is very tight. The activities are rarely common activities for the whole family, but each family member has its own rhythm.

The modal split is changing in favor of the car

Despite severe congestion, pollution, accidents and stress, the popularity of the private car is increasing. The time wasted in traffic congestion is an enormous economic burden on the inhabitants of the large cities.

The road network cannot be expanded

The cost of expanding a highway in an existing city is too high and the inhabitants react strongly against it. The social life inside the big cities will be destroyed if more roads are built.

Conclusion: There is an urgent demand for better transportation systems


Possible Solutions:

Public Transportation Systems

The traditional Public Transportation systems are too inflexible by nature to become an attractive alternative to the private car. It is impossible to cover a suburban area with attractive Public Transportation without excessive cost.

Land Use Planning

Careful planning could after a long period result in cities with a structure which can be served better with traditional Public Transportation systems. However, it will take a very long time and it is politically very difficult to manage.

Personal Rapid Transit

A system with on-demand service will be able to serve the inhabitants in the dense parts of a city much better than the traditional Public Transportation systems. The waiting times are shorter, the comfort is higher and passengers can have a larger degree of privacy.

In suburban areas PRT cannot serve well, so its scope is limited.

HOV lanes

Special lanes on the highways reserved for Heavy Occupancy Vehicles can increase the capacity of a given highway if a large number of cars use it. However it is very difficult to coordinate the travel rhythm of individuals.


Ordinary cars modified in order to be able to drive quite close at high speed (platooning) can increase the capacity of a highway. The consequences of system failures are very serious.

A 100% fail safe system does not exist.

Traffic Management

Road pricing can be applied in order to reduce the traffic, but at the same time the activity of the city is reduced.


Many business activities can in the future be performed via telecommunication networks, but an increasing part of traffic derives from other kind of activities, which cannot be substituted by electronic communication.

The RUF Dual-Mode Auto/Transit System

A completely new system combining the flexibility of the car with the good environmental qualities, safety and capacity of train systems.

It is based upon small and medium sized electric vehicles which can drive as normal electric cars with small batteries, but which can also "ride" on top of a triangular monorail and be close coupled to form trains.

A RUF dual-mode system can be created without introducing new and unproven technologies. A new combination of known technologies makes it possible to drive either on normal roads or on a special rail.

The RUF system is both a system for individual transportation and a public transportation system. This makes it possible to start the system as a substitute for the existing unpopular public transportation system and then gradually open the system for individual transportation.

It is purely electric which means that any improvement in the technology to produce electricity will have effect immediately.

A RUF-standard will be defined, so that all car manufacturers can compete to deliver the most attractive and affordable RUFs to the system. A world-wide standard will ensure that mass-production technologies will be used so that cost will be minimized. The problem with lack of compatibility between train systems will be avoided.

The RUF system will start in big cities, but the system can be expanded until it finally covers all relevant land areas with a network of rails. The mesh size can be made as small as the society will accept. The denser the mesh, the smaller the batteries for the vehicle.

With a RUF system, travelling will become a pleasent experience. Travel time is short, pollution is extremely low, safety is high, noise is low, komfort is high and the travel time can be used constructively. The city will become more effective and attractive to live in.

What Can The RUF System Do ?

The RUF is a small electric car
On normal roads, the range is 50 km and the maximum speed is 80 km/h.
Small batteries compared to normal electric cars.
Low weight and rolling resistance.
A triangular lengthwise channel allows the RUF to "ride" on a triangular rail.
The MAXI-RUF is a 10 passenger APM unit.
The RUF-rail can also carry MAXI-RUFs. They can be used as a very flexible Automatic People Mover system (APM).
The front seats can be folded so that a wheel chair can enter the vehicle.
The MAXI-RUF can be used as a mini-bus on the roads when it is supplied with a drivers seat.
The RUF is a dual-mode car.
It can go directly from road to rail at 30 km/h.
It has smooth rail wheels with very low noise.
On the rail it has a top speed of >150 km/h.
Switching is performed automatically under electronic control. The RUF leaves the rail, drives a short distance at 30 km/h as a car, selects a new rail or leaves the system without stop.
The RUFs can form a train.
The front and the rear of the RUF are matched.
The air resistance of a train is very low. Energy consumption at 100 km/h is reduced to 1/3 compared with individual driving on a road.
The capacity of a rail is very high.
A very effective rail brake ensures high safety.
Comfort and privacy is as good as in a car.

Which Problems Can The RUF-System Solve ?

All emissions are minimized.

Pollution and CO2-emission are reduced due to the low energy consumption.

The energy consumption is low because the air resistance is minimized by close coupling and the rolling resistance is low.

The low emissions are also remote.

Noise is very low

Congestion can be reduced.

The RUF system is a public transportation system with the same flexibility as a car. When many car drivers use the RUF system, congestion will be reduced.

RUFs can be public or privately owned. The public RUFs can be left at stations in the dense parts of a town.

The capacity is high and flexible.

The close coupling, combined with the very effective direct rail brake, allows high capacity of the rail. All passengers are seated.

Intelligent train formation can be used to increase the capacity further.

The Automatic People Mover part of the system can offer 24-hour service.

The RUF has unlimited range on the rail.

The normal electric car has a severe range problem.

The RUF takes current from the rail and uses regenerative braking.

The costly and heavy batteries are reduced to 1/3 the normal size for electric cars.

The batteries can be charged while the RUF is "riding" on the rail.


The RUF Rail

The rail is based upon a standard I-beam.

The I-beam is surrounded by steel plates and the upper part is covered by fiber concrete.

The rail is carried by masts. Mounting is easy and no ground leveling is needed.

The rail is "Ultra Light" compared to other elevated train systems. Low cost.

If there is room in the middle of a highway, the rail can be placed there at ground level.

A special rail brake uses the top of the rail.

Normal braking is regenerative.

Emergency braking is done by pressing against the sides of the rail. Braking power can be increased by exerting more pressure.

The RUF is completely stable during braking.

Ice and snow cannot cause problems because the braking rail has near vertical sides.

The RUF takes power from the rail.

The batteries are charged while the RUF is on the rail. Power for heating and cooling is also obtained from the rail.

The range on rail is unlimited.

The regenerative braking power can be returned to the system via the rail.

In case of a rail power loss, the RUF train can continue using the batteries.

RUF switching involves no moving rail.

When a RUF has to change from one rail to another (or change to normal roads), it leaves the rail at 30 km/h. Under electronic control, it drives a short distance on normal wheels and select the new direction.

Before switching the RUF is separated from the rest of the train by at least 5 meters.


RUF Applications

RUF access via a personal smart card.
The RUF can be privately owned, but it is more beneficial to rent a RUF. It is less expensive and you have no parking problems.
The payment is effected by using a personal smart card and vandalism is prevented.
"Dial-a-RUF" service is possible using the MAXI-RUF with chauffeur.
The RUF can be used as an APM.
A very flexible Automatic People Mover system can be made using a mixture of dual-mode RUFs and MAXI-RUFs.
Very frequent train departures.
High redundancy. A problem in one berth will not block the RUF flow.
Non-stop travel from station to station is possible.
The RUF can be used as a hybrid car.
When the RUF is not on the rail, the triangular channel can be used to mount a special hybrid unit.
It contains an optimized gas engine, a gas tank and a generator.
The mounting can be done very quickly.
The range, off rail, can be very high.
The RUF is ideal for a subway.
A tunnel tube can contain 3 RUF rails in stead of 1 normal rail.
Stations at street level are possible because the drive system allows relatively steep slopes.
Acceleration and deceleration by gravity can further reduce energy consumption.



The RUF Dual-Mode technology which is currently under development in Denmark, can solve the dilemma between the demand for more effective individual transportation and the protection of the environment.

The present public transportation systems are not sufficiently attractive to be an alternative to the private car. The RUF system can offer almost the same flexibility as the car, eliminate congestion and protect the environment.

Decision makers all over the world have to find solutions to the problems of transportation within big cities if they are not going to be strangled in congestion and pollution.

The RUF system is a promising new possibility.