n. While this is a very small fraction of the current spending on mass transit, in addition SkyTran would be faster, more accessible, and would have more possible destinations than the current mass transit system in San Francisco. After considering the money saved on mass transit and other savings, SkyTran would provide more than $350 million of benefit per year and pay off in less than 7 months. In addition to this, San Francisco would have less use for large roads, and could sell a large amount of road space for other uses. Inner city land is a premium, and if half of it were sold (leaving plenty of road-space for cars and transport), almost $10 billion of land could be unlocked and sold for city profit.
That was all public benefit - and similar effects would happen to the private sector. Ex-car users would save large amounts of money per year, and private parking lot owners could sell more than $6 billion of parking lot space. After 30 years of this system, at the same ridership, the city as a whole (public and private) would have incurred $28 billion of benefit - a staggering 13,700% return to investment. Keep in mind that a system like this maintaining a constant ridership is highly unlikely - it is much more realistic that more and more people would use the system as time went on - increasing profit and total benefit and making this incredible return to investment an underestimate.
The system provides more than just monetary benefit. It also would save more than 21 million man-hours per year - enough to build 3 Empire State buildings. The Golden Gate bridge was built by 25 million man-hours, and the Empire State building was built by 7 million man-hours.
One might disbelieve the estimated $1 million per mile, and that's fine. If SkyTran instead cost 10 times as much ($10 million per mile) the benefit drops from $28 billion to $27 billion after 30 years. The reason for this is that SkyTran's benefit lies in its operating costs - not its upfront cost. SkyTran can save the money we spend on gasoline, roads, repairs, insurance, and countless other things.
One large effect of a SkyTran grid-system is that car-related spending would rapidly decrease. This would most likely cause economic trauma in all sectors dealing with cars, and job losses to match. About 30% of retail spending is on cars, and a rapid change in such a large market would be devastating to those areas. The devastating effects on sectors serving the needs of automobiles will produce a barrage of political resistance, since this sector of the economy is controlled by powerful interests.
Local pollution would also greatly decrease. Automobiles generate about 60% of all harmful emissions, and SkyTran would decrease the use of cars by a significant percent - perhaps reducing emissions by 20% or 30%.
If the system were much larger (say extending throughout California), it would usher in an age of unprecedented mobility and transform the climate of the transportation industry. One effect is that gas prices would go down because of decreased demand. This probably wouldn't happen right away, because gas prices are more determined on the supply side - but oil prices would drop. A more important change would be that people could commute and travel farther. If SkyTran was built in a grid system throughout California more than 1/2 of the entire state could commute to San Francisco (in less than an hour and a half). This would have profound effects on the employment situation in the US, allowing people to take jobs that wouldn't previously be feasible.
A more obscure but significant effect of a large grid system is reducing airport gridlock. Billions of dollars are spent yearly to solve airport gridlock problems, and those billions could be saved if the SkyTran system covered more than 300 miles surrounding an airport. Airports could focus on longer distance flights, and could use space previously used for car parking to expand the airport.
SkyTran is a unique PRT design that has obvious advantages and could provide enormous benefit to any area that built the system.