Pro and Cons for RUF Dualmode


Palle R Jensen, RUF International, Denmark

When I started developing the RUF concept, I was not tied up to any specific technology. My driving force was to find out how to solve the problems of modern traffic. It was obvious to me that traditional public transport couldn't appeal to people who were used to drive a car. It was also clear that the cities would be destroyed if the car was given the space it required. It was a terrible dilemma.

Electric cars seemed appealing, but from the users point of view they didn't represent an improvement. They didn't pollute at street level, but the difference couldn't be noticed until a major part of the vehicles were electric. On the other hand they got a range problem or very heavy and costly batteries. Traditional rail technology seemed to have high capacity, but only if large heavy vehicles were used. At grade systems seem to be very dangerous in cities and derailment could occur. Steel rail makes it possible to have very low rolling resistance, which is good, but at the same time you get very poor braking power.

Monorail technology has a "sexy" appeal to it, but used as a train solution, it doesn't really solve any problems. Automated people movers have gained wide acceptance and the safety records are excellent. Most systems built until now have been trains running automatically, so they still suffer from the same problems as trains (long safety distances because of poor braking).

PRT systems are emerging and they seem to have a great potential when we are talking about serving a limited number of destinations. They still suffer from the inflexibility represented by the rail. In modern cities, a network has to be very extensive and costly to serve most of the city.

Automated Highway Systems have been tested, but the technology is so critical and the implementation is so difficult that the development has now been stopped in USA. I think it will be impossible to convince the users that the invisible safety critical software will work 100.00% of the time. When a failure happens, how will the average driver know how to handle the situation? He is not a trained pilot and he only has a fraction of a second to react.

All these considerations have led me to conclude the following:

FIRST: It has to be a Dualmode system. Only this way we can compete with the car which can offer door-to-door transport.

SECOND: It has to be personal. If people by their free will have to give up their car for something else, it cannot be shared with somebody else. People identify themselves with their vehicle. It has to be similar to a car. Design variations must be possible. New attractive features are welcome.

THIRD: It has to be electric. We have to get out of the oil dependence within the next 30 years. The production of oil will peak and the price will skyrocket. The greenhouse effect (i.e. global warming) will demand that we change away from oil.

FOURTH: It has to be elevated. In order to avoid conflicts with ground transport, the main part of the system has to be separated from the ground system.

FIFTH: It has to be using monorail technology. In order to have a very slender guideway, monorail technology is excellent. A triangular monorail is a mechanically optimal solution. The access to the top of the rail at the same level as the vehicle's center of gravity makes it ideal for powerful braking and traction.

SIXTH: It has to be based upon many small units. Elevated trains require very heavy (and costly) rail modules. Many small units make a more distributed load, so cost can be saved. Many small units also mean very high frequency. This way timetables are no longer needed.

SEVENTH: It has to be automated. In order to optimize the flow of vehicles, it is essential to use the possibility to know the position and speed of all vehicles approaching a junction. This is not possible in a manual system, but in an automated system with distributed control, it is possible.

EIGHTH: It must have a switch without moving rail. In city transport, flexibility is essential. A slow moving rail would make it impossible to obtain sufficiently high flexibility. A magnetic guidance principle used at low speed is proven technology and can solve the problem.

NINTH: It must be possible to implement it gradually. The system will have to start as a limited system. A system operator will have to supply the initial vehicles to get started. This is possible in many ways. Start as a feeder line for a public transport system is one possibility. Start as a system for an amusement park is another.

All these requirements have been combined in the RUF concept (see The RUF concept: RUF is a dualmode system based upon electric vehicles. It can be used both by personal vehicles (ruf) and by shared vehicles (maxi-ruf). It uses monorail technology and can be elevated. It is automated when using the monorail. All units are small. It uses a switch based upon magnetic guidance. It can be implemented gradually starting as public transport or limited systems.

PROs: RUF solves the congestion problem because it supplies new capacity on top of the existing system. RUF solves the pollution problem using electric propulsion. The battery problem is solved using power from the guideway. Small batteries mean low weight and low cost. The energy consumption is lowered significantly compared to car driving by means of closely coupled vehicles on the guideway. This will reduce the growth of the greenhouse effect. The safety problem is reduced since closely coupled vehicles cannot collide. The special rail brake makes it possible to have a very powerful braking for emergency situations.

The lateral guidance is perfect because all vehicles are "riding" on top of the triangular guideway. The guideway does not collect snow during winter. The friction at the traction wheels is adjustable because the drive wheels have access to both sides of the top of the rail. The same propulsion system is used both for manual and for automated driving. Normal braking regenerate part of the power which is sent back to the system. It will not overload batteries.

Very attractive public transport can be implemented using maxi-ruf vehicles. They can offer door-to-door transport at high level of comfort. Access to maxi-ruf is extremely easy. Every seat has its own door. Security using maxi-ruf is very high. Seats are single seats. There is no standing in the RUF system. System economy is excellent. Inexpensive modular guideway assures low construction cost. Dualmode ensures that the number of potential users is high. The users are willing to pay a relatively high fare, since the automated part of the trip can be used for many constructive purposes. A commuter using a ruf can earn money while commuting. An onboard computer makes the commuter "on-line" both mechanically and electronically.

CONs: A channel through the vehicle takes up space inside the cabin. BUT: The test vehicle has shown that this is only a minor problem. The design has to comply to the RUF standard. BUT: Several designers have already given very different suggestions to how a ruf might look. New attractive design features are possible. The onboard computer can be used as a new design attraction. The triangular notch in front of the vehicle looks strange. BUT: Some designers will probably suggest solutions where it is covered when the ruf is driving as a car.

The range of a ruf is limited (range must be at least 30 miles) when driving on batteries. Destinations farther away cannot be reached. BUT: A supplementary hybrid unit can be mounted in the empty slot under the ruf when it is not using the rail. With that unit mounted, the range is the same as for an ordinary car. A maxi-ruf has doors in both sides. This means that passengers have to leave the bus at the wrong side. BUT: The maxi-ruf is not as wide as an ordinary bus, and it can be parked so that the rear of the vehicle protects the embarking passengers. It is also possible to organize the seating, so that the left side seats (right in UK) only is used by passengers who are leaving the bus in places where it can be done safely. Since every seat has its own door, it is possible to control where passengers are seated.

CONCLUSION: The CONs are not very problematic and the PROs are very attractive. The test track has shown that the concept is realistic. Calculations show that it is economically viable. There is an increasing political interest in the RUF concept.


Last modified: September 3, 2000