More Thoughts on Guided Personal Transit - a Response to Mr. Turnbull
Palle R Jensen
Mr Turnbull has given us the chance to experience how an educated newcomer looks upon our dualmode debate. This is very important for all of us and especially for those of us who work full time ++ on our concepts.
In the following I will try to respond to each of Mr. Turnbull's six observations seen from a RUF viewpoint.
First, Mr. Turnbull suggests that we concentrate on the here and now problem (freeway breakdown) and forget about inter-city transport with the same system. I agree that it is problematic to use the same vehicle in the urban setting as well as between cities with separation of more than 300 miles. The reason is, that the power required to drive at high speed will make it necessary to carry a very powerful engine at all time. Since inter-city trips are rare compared to urban trips, it would be a waste of power (money). On the other hand, I think it is important to consider the possibilities for expansion, once the first phase is in place. For that purpose I would suggest a solution where ruf-trains are pulled by a RUF locomotive. This way it is possible to obtain high speed with the simple ruf vehicle.
Second, Mr. Turnbull has the impression that the dualmode developers only focus on hardware where we should focus on operation and control. As one of the few who have been participating in this debate since 1994, I can assure everybody that there has been a very intense debate some years ago. The scalability problem of control systems has been intensely discussed. Maybe we should update this debate. It is a vital part of the system and not all problems are solved.
Dr. Ed Anderson has made a simulation of a pure PRT network. It is an excellent example which should be repeated in the dualmode world. In Denmark I am actively seeking funding for making a similar computer model of a network, so hopefully I will be able to demonstrate it soon. The basic RUF philosophy is, that every junction has control of the incoming flow of vehicles. If the flow is low enough, every train is split before the junction and the rufs are guided through the junction separately. If the flow is close to maximum, trains are composed intelligently, so that a train only has to be split a few places: Straight ahead - Right - Left - Exit. The junction is constructed in such a way that the 4 sub-flows are running along separate guideways in the junction (impossible to explain in words :-)). The overall control system looks for "overheating" of certain sections. There are always different possibilities in a network to get from A to B, so if one section is overheated, some of the flow can be rerouted.
Another way of looking at this proble is to make the use of the rail so attractive that the users will pay a high fare for using it. If a commuter can actually work while he commutes (coupled to the Internet via the guideway itself) he is willing to pay a high fare and the operator will earn a lot of money. The operator will therefor create parallel guideways if the section is "overheated". I have made a spreadsheet with calculations for a network in LA. The IRR is 35% based upon a peak flow of only 30% of maximum flow.
Third, Turnbull asks: Does one size fit all? The RUF philosophy is to create a standard defining the interface between rail and vehicle, but let the car manufacturers create a variety of rufs for the guideway. These could be anything between a small 2-seater and the largest 10 seat maxi-ruf. The vehicle design can differ significantly even though the rail has to fit inside. The rail is made very simple and slender using a minimalistic triangular shape. The system will be a dualmode system in Southern California, but would be a PRT system in Manhattan or be based upon maxi-ruf vehicles. Automatic parking of privately owned vehicles can also be used in order to prevent the rufs from having to enter streets adjacent to the station.
Fourth, Turnbull suggests that our hardware is overdesigned! This may be true at this point, but for an engineer it is important to have the opportunity to test several versions before the final design can be decided. Please have patience. A lot can be clarified with simple means before using a lot of money on the final design. Most people are impressed with the minimalistic RUF guideway. It may be more expensive than old fashioned rail, but a solution based upon traditional rail would not be able to perform safely, quickly and flexibly enough in an urban setting.
Fifth, he argues that Personal Transit should not be expected to replace freeways. I agree - in the short and medium term. Cars running along freeways are using a lot of resources. I think that when the oil supply reaches its peak the price will go up and a fast transition to electric propulsion will take place. If a RUF system is developed at that time, it could take over quickly. Not 100% but a very significant number.
Sixth, I agree that there is not a big difference between PRT and dualmode. As I see it, many PRT systems cannot be expanded to dualmode. A few can. RUF is born as dualmode, but it can also act as PRT if required. Since I think that dualmode is essential, I think it would be wise to ensure that a system has this possibility, even if it may be started as a single mode system. I don't see the pendulum swinging towards pallets. On the other hand, I can easily implement a pallet vehicle using the RUF guideway, if need be.
Final remarks: My experience after many, many RUF presentations is that the RUF vision is easy to sell to people when they get the opportunity to hear the whole story. This may be difficult when we talk about politicians. Nevertheless, I have been having meetings with politicians in Denmark, Holland, Mexico and USA. Especially in Denmark, the access to politicians is relatively easy. This is the way I try to create a "hunger" for a better solution in order to get a breakthrough for RUF. I am very optimistic that it will happen in my lifetime (I'm now only 56 years old).
Last modified: May 27, 2001