The costs of transportation systems consist of a number of related elements. Skytran is fundamentally lower cost than other systems because most of its components are much smaller than the equivalent in other systems, and in turn because it uses much less land as well. For example, ironically, the wide roads that make driving easier in a car-based city like Los Angeles, themselves take up a fair amount of land that makes everything further apart, requiring yet more roads! Skytran's tiny surface footprint (about a square foot for a pole every 30 feet, or none at all where it's attached to buildings) typically does not require any additional land set aside for it. It also requires much less land to park vehicles (vehicles waiting above the sidewalk between arrival and departure stations require no land; only an easement like power or telephone lines do). Extra vehicles can be parked densely in facilities many stories high (it's much cheaper to build a parking garage for 250-pound SkyTrans than multi-ton cars and SUVs) located in cheaper outlying areas and dispatched automatically to where they are needed.

Besides measuring direct costs, it's also important to account for the indirect costs such as the value of drivers' time saved not waiting in traffic, dramatically-improved air quality and safer and more livable city neighborhoods not split by freeways or rattled by trains going by on elevated tracks. In financial terms, these translate into the value SkyTran offers individuals that use the system, as well as the organization or government operating the system.
A SkyTran vehicle weights between 200 and 300 pounds as opposed to more than 20 times that for automobiles. This light weight is accomplished because:
- Efficiency requires only a small engine.
- Guideway power source means no heavy batteries.
- Strong composites make a light shell. 
- Only 2 seats means carrying around usually empty seats is avoided.
- Seats integral to the struture reduce the need for extra structural components.
 
This light weight benefits not just the energy usage of the cars itself but it also reduces the need for heavy and expensive guideways.. By contrast, roads have to support vehicles that weigh in excess of 5-tons. Furthermore, weight-limits are not well enforced in many areas and this leads to high maintenance cost for roads [1]. Train tracks have to be even heavier because of the weight of trains - even light rail trains can weigh greater 
 
Since SkyTran's supports and vehicles are light and small, they don't take up much space. Train tracks and freeways need giant swaths of land to be built, but SkyTran poles and guideways are only one foot wide. SkyTran can be built on existing highway medians, ordinary sidewalks, or even attached directly to existing bridges and buildings. Because the Skytran car is light, it needs less structural material to support its own weight.
Because it uses so little energy, the motor can be small an thus lighter, so the car needs less energy to accelerate and thus
a smaller engine. Because there is no "gas tank" or need to store energy, less energy is needed to move the vehicle. Because the main brakes are the motor itself, there's no need
for primary brakes, reducing the weight and therefore less strain on the braking system. Because Skytran's guideways are narrow, they don't take up much space.
Land isn't needed for gas stations, parking spaces, auto parts stores and a host of other automobile-centric space-consumers. This allows people to live closer together reducing the distances they must travel. Skytran's technologies work in concert
to reduce requirements of the transportation system thus optimizing energy usage well beyond other transportation systems.

 

Transportation Mode	Capital cost per mile ($M)	capital cost per passenger mile	energy cost per passenger mile ($)	maintenance cost per mile	Other operations cost per passenger mile	total cost per passenger mile ($)
subway	100					0.70
light rail	65					0.45
bus						0.20
car						0.56
Skytran	10		0.01			.02?

These are too many notes. We should format this information better. For example, we can refer to the table inside paragraphs, rather than have notes that are specific to the table. Some of these notes are sources or notes about sources - these can be enumerated and listed as a footnote.

Table Notes: 

1. Costs are given "per passenger mile" i.e. the cost that it takes to move one passenger one mile in the system. This is the cost the public pays both directly in fares or indirectly in taxes for construction and fare subsidies.
2. Costs "per mile" refers to a mile of one lane of roadway, one railway track, or a one-way SkyTran guideway. Note that a bi-directional Skytran guideway is expected to be only 1.5 times the cost of a uni-directional guideway, because it can use the same utility poles and electrical and control infrastructure. This means guideway cost per mile is 25% less in each direction.
3.  Capital costs vary due primarily to urban vs rural costs. We use an average of urban and suburban costs.
4. Skytran guideway cost is listed as the cost we anticipate early systems will cost. Since all the components of a guideway can be mass-manufactured, costs will decrease dramatically as volume goes up ("learning curve"). We use the initial-system costs to assess viability of the first systems.
   
5. Capital cost per passenger mile will vary with the number of pasengers per hour carried by one lane of the system. A Skytran guideway operating with 1 second spacing between cars, with 1 person occupying each car, will carry 3600 passengers per hour. A mature system will be able to operate with 1/2 second spacing (7200 passengers/hour, or more if a significant fraction of the cars carry more than the automobile average of 1.2 passengers).
6. Energy costs include gas, diesel or electricity. Skytran needs about 1/10 the energy of an average automobile.
7. Maintenance costs include cleaning, repair, and snow-removal.
8. Other operations costs include subway and bus drivers. Skytran needs no driver. For cars we assume that drivers are "free", but of course, if you'd rather be working, reading, watching a movie or taking a nap as you can do in SkyTran, then SkyTran beats driving.
9. Total cost per passenger mile, 2005 figures from http://www.treehugger.com/files/2007/07/number_of_the_d.php
10. These numbers are 2008-2009 estimates. It is difficult to come up with exact numbers, but we think they are reasonable and conservative approximations.

References:

1. http://www.ti.org/vaupdate32.html
2. http://www.lightrailnow.org/facts/fa_00016.htm
3. http://www.publicpurpose.com/ut-buswayopcap.htm
4. http://www.debunkingportland.com/Printables/RailPacket.pdf
5. http://www.fta.dot.gov/documents/SF3AA.doc
6. http://www.treehugger.com/files/2007/07/number_of_the_d.php

What track density can a city support?

Does "capital cost per passenger mile" in the above table make sense?  Here's some related reasoning from Howie's email 2/15/2009: calculating the affordable track density based on a per-passenger revenue model (related to "capital cost per passenger mile" by assuming some average number of miles traveled per month or per year):

It's just like a mortgage Present Value (PV). You figure out the payment you can afford; then calculate from that and the interest rate and repayment period the amount you can borrow (mortgage Present Value) to buy or build your house. SkyTran's maximum "monthly payment" per passenger is the amount of gross profit per passenger (average miles traveled * fare paid) you can allocate to amortizing the system's construction costs, after paying operating and maintenance costs (and investor profit if the system is privately owned).  For example, if a passenger pays $150 per month for all his use of one of the first SkyTran systems, and the owners allocate 74% of that ($111/month) to amortize initial construction, borrowing the money for 10 years (out of conservatism and fear of obsolescence -- the system itself should last much longer) at 6% interest (private lenders would want more for a new technology investment, but government incentives for green technology should bring it down), then their Present Value per passenger is $10,000. Even at the initial pre-learning-curve construction cost of $10M/mile, that's enough to build one mile of track for every 1000 riders.

How does this translate into grid density you can support?

1. To get riders per square mile, multiply population per square mile by assumed %market share. I believe I saw a 40% estimate from a transportation planner once; anybody have that reference? 
2. Miles of guideway to build at a given grid spacing are 2/spacing, because you need to build 1/spacing miles of track horizontally + 1/spacing miles vertically in each square mile. So:

• 2 guideway miles for a 1-mile grid    = 1 mile left vertical + 1 top horizontal segment (the right vertical and bottom horizontal segments are counted for adjoining grid squares)
• 4 guideway miles for a 1/2 mile grid = 2 vertical and 2 horizontal segments
  
• 6 guideway miles for a 1/3 mile grid = 3 vertical + 3 horizontal
• 8 guideway miles for a 1/4 mile grid = 4 vertical + 4 horizontal
  
• ....

So with my guesstimated 1 mile/1000 riders and 40% ridership, the formula is
grid spacing in miles     =      (2 * 1000) / (population/sq mi * 0.40 )
                                      =      5000 / (population density per square mile)

Example:

According to http://www.census.gov/population/www/documentation/twps0027/twps0027.html#tabA Los Angeles' population density in 1990 was 7,400 people/sq mi while New York's was 23,700.  So using my conservative 1000 riders per mile and 40% SkyTran ridership, I get reasonable numbers:

• Los Angeles:    5000 / 7400   = .7 mile grid spacing
  
• New York City: 5000 / 23,700 = .2 mile grid spacing
  

Note that these are very rough estimates, but they show that even using initial SkyTran track construction prices, a city can afford a reasonably dense grid of SkyTran lines, enough to permit dramatic replacement of car miles with SkyTran miles.  Even a 40% drop in air pollution and traffic congestion would be a huge benefit.

How will SkyTran affect individual finances?

Living in the suburbs isn't always cheaper once commuting costs are figured in; see http://realestate.msn.com/article.aspx?cp-documentid=13108346