Hybrid-Electric Roadtrains by 2020

Safer, Quieter, Cleaner and More Sustainable Land Transportation

Why are road-trains or car-trains better than mass transit?
Would it cost an individual less than mass transit?
How does someone go about connecting their vehicle another vehicle in a road-train?
How does guide railways fit into this?

Views: 49

Comment by Bruce McHenry on April 6, 2010 at 6:38pm

Why are road-trains or car-trains better than mass transit?

There are really two questions here. One is whether roadtrain compatible personal cars would be better than mass transit. The second is whether roadtrain compatible public transit cars would be better than mass transit.

The first observation is that passenger cars, SUVs, light trucks and vans accounted for 4.6 trillion passenger-miles in the US whereas bus service of all types provided 0.15 trillion p-m and train service including Amtrak, commuter rail and transit provided 0.035 trillion p-m. Bus plus rail provided 0.2 trillion p-m which is only 4% of all passenger-miles. (Source: Bureau of Transportation Statistics 2010 Pocket Guide, pg. 19) So clearly passenger cars have won dominant market share. This has occurred despite government subsidies that typically pay 80% of the cost of transit.

Why have cars become so dominant? There are many reasons including privacy and cleanliness, and the ability to carry a substantial load, but the reason a car is chosen most of the time is that one is available without notice and can be driven non-stop to the desired destination in about 1/3 to 1/2 of the time needed to take a bus or train.

Roadtrain compatible cars would have all the convenience of regular cars and so will achieve similar levels of consumer acceptance relative to transit. In fact, the roadtrain versions will be more desirable than conventional cars because they will be substantially faster during rush hours. This is because roadtrains will be granted priority over conventional traffic owing to the fact that they will use the available road space much more efficiently.

With regard to the second interpretation of the question, roadtrain compatible vehicles will also be used to provide much faster public transit service. In order to minimize wait times and the frequency of stops, these vehicles will be much more common than buses and much smaller. In order to reduce driver costs, they would be driver-less and able to autonomously join passing roadtrains, and separate from them to stop and discharge passengers.

Transit based on roadtrains would be more desirable because of the shorter trip times. The driverless transit cars would have operating costs much more similar to personal cars. It is likely that they could be operated with little or no government subsidy as drivers account for more than half of bus operating costs, in the US.

Comment by Keith Eshelman on November 27, 2010 at 12:19pm
I would briefly say that traditional railroads traversed a geometric line. All start and stop points must be on that line. The auto-mobile replaced the horse-drawn carrage, making the newfangled carriage more popular than ever. It traverses a geometric plane by combining line segments from any point A to any point B.

Road-train capable cars will be much better than today's automobile.

Automobiles in production today have some amazing computerized features. I think much more is coming soon.
Comment by Bruce McHenry on June 20, 2011 at 2:55pm

Having answered Noreen's first two questions below and more than a year ago, I will now answer her 3rd and 4th questions.  




Before roadtrains, there will be Dedicated Short Range Communications (DSRC) aka WiFi for cars as well as G4 and later generations of wireless technology.  All of these can be used to coordinate hooking up with other roadtrain compatible vehicles.   This will be particularly important in the early stages of adoption because when there are few cars with which to hitch, drivers will need to time their entry into the arterial flow in order to meet up with a passing roadtrain.  

Radio communications between the vehicles will also be useful for optimizing the sequence of the cars.  Apart from a rule that the heaviest vehicles lead, cars can be sequenced such that the next car to leave the roadtrain is at the end.  This will help minimize the number of times that the train has to be split and re-joined.  However, the roadtrains will still need to split and re-join in order for cars to get inserted into the middle.


The meet up and the sequencing functions depend on integration with a navigation system into which the drivers have entered their destinations.  


However, there will also be a mode that does not require exchange of destinations by radio.  In a roadtrain compatible vehicle, there will be a switch that works very much like Adaptive Cruise Control.  Available now in luxury cars, ACC allows drivers to set a speed but decreases the speed in order to follow a car ahead in the same lane.  Roadtrains will extend ACC by hitching with a vehicle ahead if it is operating as a roadtrain and in the same or heavier weight class.  




Guideways are a very infrastructure intensive evolution beyond roadtains yet which will depend to some extent on the existence of roadtrains.   Many guideway solutions would permit the use of vehicles that can also drive on the road.  The guideways would be able to carry very high traffic volumes and could therefore also discharge large numbers of vehicle onto the road.  With their ability to increase lane capacity by 3-5 times, roadtrains may be considered to be a pre-requisite to building guideways.  Roadtrains will also require very little new infrastructure since they are compatible with the existing surface streets.


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