Here is a powerpoint that lays out the case for electrical guideways to increase car and truck efficiency by 3 to 6 times The cost would be comparable to building the national highway system.
BTW: dual mode means the vehicles can drive by themselves on regular roads when they choose not to attach to the guideway. So individuals will have the choice of where to drive. However, not driving on the guideway would be like driving on a very bad dirt road. Guideway versus regular driving would be faster, safer and more efficient.
A dual mode car looks like this.
50-80% drag reduction. This can also be achieved with robotically driven vehicles or advanced adaptive cruise control.
A dual mode vehicle can have train like contact to the guideway which enables 3 to 6 times the rolling efficiency
The rolling efficiency is from the hard wheels
The overall running efficiency is from the combined aerodynamic improvement and the rolling improvement
The total improvement includes the propulsion improvement
Ten times more cars per guideway. Some of this benefit can be achieved with car and truck platooning using advanced cruise control.
Miles of guideway needed is about 100 miles per million people.
Costs to build the guideways is about one trillion dollars for the USA
However, the savings are
$140 billion/year for drive time
28 billion hours per year of drive time @ $5/hr
$125 billion/year from traffic delays
$100 billion/year from traffic accident reduction
$230 billion cost of car crashes
$100 billion/year from lower military and homeland security costs
$50 billion/year from reduced car maintenance
$150 billion/year from increased longevity of cars
$70 billion/year from less truck driving, less highway maintenance, more car sharing, reduction in other transportation subsidies
Total of more than $500 billion/year in savings would pay for the system in 2 years.
It would take a phased deployment over about 40 years to realize a complete deployment of electrical guideways and dual mode vehicles.
If nanofactories were developed then increased production capabilities could accelerate the deployment.
The source of the e guideway document has a website
Revisions of the long range transportation vision
An examination of road trains
A dual mode bus/truck. Notice the guiderail connection in the bottom middle.
Wikipedia has an entry for the future of the car
An article on road trains
An online powerpoint presentation on road trains
A wikipedia entry on autonomous cruise control