There are two broad types of operating costs: 'direct' and 'indirect'.  Direct costs are proportional to the number of vehicle miles logged, while indirect costs are those that are incurred even if vehicles don't log any mileage.  We'll examine direct costs first.

A big part of the direct operating cost, obviously, is energy use.  Fortunately there's a great deal of data on how much energy vehicles like ours will use, thanks to dozens of government-funded studies on the energy use of small electric automobiles.  These studies show that electric automobiles use about 0.1 kwh per mile at 40 mph.

But these studies involved battery-powered vehicles, and batteries are very heavy-- typically half of the total weight of the vehicle!  By contrast, since our vehicles draw their energy from a sliding contact on the guideway, they're considerably lighter than the automobiles in the studies noted above (800 lbs max weight versus about 2500 lbs).  Thus our vehicles will almost certainly use less than the 0.1 kwh/mile used by the heavier autos.  But for now we'll use this number.

Of course 0.1 kwh per mile is just the energy needed to cruise; we'll also have to air-condition the vehicles for part of the year.  Ironically, so little power is needed to move the vehicles at 40 mph that the energy needed to air-condition them--normally a matter of little concern--is about equal to the energy to move them.  Thus during the cooling season our vehicles will be using roughly 0.2 kwh per mile.  The annual average power use should then be about 0.15 kwh/mile, depending on local climate.

The cost of the electricity used by our system will depend on whether the system generates its own, buys from the local utility company or from a cogeneration facility.  For now let's assume 10 cents per kwh.  In that case our average electrical cost (over the entire year) will be around 1.5 cents per vehicle-mile.

In addition to electricity there are two consumable parts whose rate of consumption is directly proportional to mileage: the sliding power pickups, and tires.  For a first hack let's assume that a vehicle set of the sliding power pickups will cost $200 (installed) and will last 100,000 miles.  That's 0.2 cents per mile.
 

With more than 1500 vehicles per loop at full capacity, using pneumatic tires would probably increase maintenance costs.  Instead we'll use either conventional tubeless rubber tires filled with high-pressure closed-cell polyurethane foam--an existing, proven technology--or wheels rimmed with solid polyurethane wear treads.  (Picture a scaled-up version of a rollerblade wheel.)

For a first hack we'll assume that with our very low vehicle weight, lack of side loads and no emergency-braking, either type of wear tread will last twice as long as car tires, or about 100,000 miles.  We'll also assume that since they'll only be about three inches wide and will use far less material than regular automobile tires, in quantity they'll cost $50 apiece, installed.  That's about 0.2 cents per mile for tire wear.

Finally we'll assume that on average, once per 100,000 miles some component on the vehicle will fail, with a repair cost of $500.  This adds another 0.5 cents per mile.  That brings our direct operating cost to about 2.4 cents per mile.

Unfortunately the cost per passenger-mile will be nearly twice this figure because during rush hours, when most passengers are travelling in one direction only, most of the vehicles will have to deadhead back to the point of high boarding demand without passengers.  So we're looking at an effective total direct operating cost--including deadhead miles--of about five cents per passenger-mile.
 

INDIRECT COSTS

Indirect operating costs (IOC's) are independent of the number of vehicle-miles logged.  Some of the items in this category are salaries and benefits for maintenance personnel and system supervisors; insurance (almost certainly a self-insured plan); the cost of lighting in the stops; and the cost of lighting and other utilities in the maintenance facility.

(One item absent from this list is the cost of debt service, because for the moment we're going to consider that our system--like most other public transit systems--will be publicly owned.)

Indirect costs are much harder to estimate accurately than DOC's, mainly because personnel costs vary so widely, depending on whether the operator is a city or a lean, profit-oriented company.  For example, because the system has been designed to be completely automatic, no human 'operators' are needed.  Our staffing would use just two human 'monitors' whose main function would be to answer questions from passengers or from people in the stops.

Of course we recognize that most people can't imagine such an extensive public transit system being "run" (as the press will invariably characterize it) by only two people, and that city operators will be tempted to add employees and administrators.
 

A second big unknown is how many employees will be needed to maintain 1600 vehicles per loop.  In this regard, knowing the mean lifetime of each component on the vehicle is overwhelmed by questions such as, Will vehicles need to be cleaned daily, or will the 'personal size' of the vehicles induce users to be less trashy?  How much outright vandalism will the system experience? and so on.

If we assume the average trip covers ten miles, the direct cost would be about 50 cents per trip.  (Recall that the estimated DOC already includes as many "deadhead" miles as revenue miles.)  If the fare is $1.50 per ride, the system would have a gross margin (revenue minus direct costs) of $1 per passenger, meaning that 3000 users per day would probably cover the indirect costs in an efficiently staffed system.

At any greater usage than this, the system would not only cover its total costs from the farebox--something no other public transit system does--but would actually make a profit.

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