A New Transportation Mode Must Reduce the Problems of Current Transportation Modes


Johan Overvest

To follow the discussions in this dual mode debate is very interesting. Because I am Dutch and I haven’t a linguistic talent, I have some difficulties to really understand every saying, however I can manage most of it. I can follow the different arguments well and I can hear between the lines that most of you are very committed to dual mode and the realizing of it. Now, I have some remarks to make in this contribution and I hope that you can understand my English.

Why do we take so much trouble to support dual mode to make dual mode be the new transportation mode?

Well, we trust that dual mode really can solve the problems of the current transportation modes. (car, airplane, train, bike, lightrail, bus and boat). Therefore, much effort is taken to invent a very attractive system and to find a way to start with it. That is very good and in this contribution I shall look to the way we want to solve the problems of the roadway system.

What are the problems of the roadway system?

Pollution; very high energy consumption; traffic accidents and victims; noise; damage to nature and to quality of life in cities: high space-use and competition with space for pedestrians, bikes, gardens, parks and even homes; isolation of non-drivers; the forming of an all the same land-use pattern and "at last the best" congestion.

It is true that electrical vehicles can help to decrease pollution. The pollution is then dependent on the way we generate the electricity. In general the less energy is needed, the less pollution is generated. This is independent of how the electricity is generated. (for example: gas, oil, coal, brown coal, wind, nuclear or energy radiated in out of the universe). This counts even when electricity is generated by solar cells, like J. Richard Guadagno told us in his contribution of November 2000, while solar cells must be produced, require land area (or lake area) and eventually broken up and replaced by new cells. So energy savings is important if we want to diminish pollution.

To make dual mode attractive, we try to make the cruising speed high. If the speed increases, the energy consumption increases. But people also tend to make more miles! Although everone has to spend some of their own time for transportation, mankind (in the western world) travels well over one hour a day. This travel time budget has been constant for about a century. Once man walked an hour a day, now man drives an hour a day and once man travelled dual mode an hour a day. This is the reason that the required energy of our proposed system can better be expressed in units of hours than in units of kms or miles. So if we will save some energy with dual mode, it has to be more energy efficient per hour! Even stronger: while automation allows man to do other things while he travels, the transportation time budget is probably getting larger. Thus the energy used per hour must be a fraction of what it is today. This needs our attention, because we want to reduce energy and polution problems.

Not only are the energy requirements affected by increased cruising speeds, also the total travel distance will increase. The newly generated traffic will soon fill the capacity of the remaining roadway system. So dual mode can cause new congestion!

The higher the average speed, the higher the travel distances and the higher the needed capacity. Not only the capacity of the guideways but also the capacity of the local roadway networks. This needs our attention, because we don’t want to make new traffic problems or worsen existing problems.

There was a very interesting debate about the use of pallets on the guideways. The preliminary result of the debate is to use pallets only as an interim solution for the chicken/egg problem. Because a pallet system doesn’t solve enough problems, we don’t want to use pallets for a long time. This is good because still polluting internal combustion engines are used for transportation. But is it real to assume that pallets can be used only for a short time? I think that the use of pallets will adversely delay the point that we have to exchange from our existing cars to dual mode vehicles. The expected time that we can drive our engines on oil (about 20 years?) will be made much longer through the dual mode pallet system (to about 50 years???). The reason is that changing something as big as our transportation system, is like changing the travel direction of a large and heavy oil tanker. I think we don't really want this delay, so preventing this scenario needs our attention.

The other problems (i.e.: traffic accidents; noise; damage to nature and to quality of life in cities: high space-use and competing with space for pedestrians, bikes, gardens, parks and even homes and isolation of non-drivers) can be split up into two problem areas: connecting traffic that uses our dual mode guideways and the traffic opening up of an area where dual mode vehicles use the roadway. The first part, the connecting track traffic, solves (or helps solving) most of these problems. That is a real gain. The second part on the other hand is not helped with our dual mode solution. Even worse: Through traffic growth the problems get bigger. This needs our attention, because we don’t want to worsen existing problems.

In the first paragraph of the contribution from Steven E. Shladover, he descrobes the advantages when cars drive themselves. (elimination of traffic crashes and anti-social driving, a higher level of mobility for the entire population, being chauffeured, less fuel consumption, less polluting emissions and more freeway capacity) Then he considers the automated highway system. But AHS can’t ever meet these mentioned advantages, because advanced driving skills will still be needed by every driver for local travel. The mentioned advantages are attractive and they need our attention because we want to make a very attractive system that solves problems.

When I think that automated guideway traffic is the future and has so many advantages, then we must design vehicles that are especially adapted to a guideway. So must we adopt PRT? In this debate we get it clear that PRT comes up short on two requirements: Door-to-door service and the possiblity to own a vehicle. This is true in the (almost?) market-ripe PRT systems like PRT2000. But in future we are able to make a PRT-like system that can handle more and more door-to-door services, or almost door-to-door services. Why? You see it is quite attractive to live very near a PRT-stop. Then you haven’t to taxi your children, no even yourself are taxied all the way home. Maybe you can even own a vehicle, that is stored in a garage near the stop. Maybe there will be made some PRT-oriented residential areas, where the mentioned local problems of the roadway traffic are not longer tolerated and are much safer for children to play. (See for instance http://www.swedetrack.com/e45subur.htm)

Also travelling to work will be easier: It is very attractive for offices to have a PRT-stop inside the building. Not only for personnel and visitors, but also for goods and parcel delivery.

An Alternative Dualmode Concept

But how can we reach the places with only a roadway connection? (Or how to reach places with only a waterway connection?) For this we need a form of dual mode vehicles. When I think of all the heavy requirements mentioned in this contribution, then I think we need something that I haven’t read yet in this debate:

We need a cabin that is specially adopted for an uncomplicated guideway, and we need special pallets for where this cabin must drive on a roadway or waterway. These roadway pallets must be available then at special stops. These stops are located near the fringes and gaps of the guideway network. The number of pallets can be adjusted to match the capacity of the local roadway system. When many pallets are needed to reach a certain area, then it is attractive to expand the guideway network. With the growth of the guideway network, the stops with roadway pallets will each time be relocated to the new fringes of the guideway network.

An other important advantage of this solution with roadway pallets is: The cabins of this PRT dual mode system are light and have  relatively little frontal surface, which saves a lot of energy (and enables us to make the guideways lighter and more compact). On the roadway the cabin and the roadway pallet may be heavier than a true dual mode vehicle. But that is not bad, while these distances and velocities are mostly quite low.

In May 2000, Kirston Henderson mentioned 26 requirements for a fully successful system. I think PRT Dual mode can meet all of these requirements (if well-engineered, of course)

In September 1998, Tad Winiecki argued that dual mode cannot do well in CBDs and that dual mode isn’t engineered to go to CBDs. The solution he mentioned then can be even better done by Dual mode PRT. The solution was: Handle CBDs with PRT stations, let people get off their private vehices there and send the private vehicles to an automated garage.

Can It Be Done?

I am really curious if  the currently designed dual mode systems are able to adopt this different way of dual mode use. A versatile dual mode guideway system is easier to apply than others.

When we are able to design a system that is real environmentally sound, like I have described in this contribution to the dual mode debate, then we can expect support from environmental groups. Mostly they are good at politics or influencing public opinion. When they are able to bring out a very attractive alternative for reducing the roadway traffic, then a real change can take place.


Last modified: January 17, 2001