BIKE: Re: More evidence that TxDOT is in trouble

[Dave W]

> TxDOT pays little attention to fuel costs and the
> stability of future 
> supply in spite of its economic importance to
> TxDOT's future;

In fact, Federally-mandated travel "demand" models are
not demand models at all.  These "demand" models are
used by highway departments to forecast how many miles
will be driven and, therefore, how many miles of roads
will be "needed" to satisfy the drivers (I put
"needed" in quotes because it really is a "want" that
has been redefined by politicians as a "need").

Standard demand models, in the economic sense of
supply and demand, relate prices and quantities of a
good demanded or supplied.  Thus, the demand for lane
miles should be a function of the price of consuming
those lane miles.

But the price of driving (consuming lane miles)
figures nowhere in computations of travel "demand." 
The price of driving is a function of many things,
fuel prices included.  In current travel "demand"
models, the quantity of lane miles demanded is a
function of the age of vehicles and the projected
driving age population.  One-year old vehicles are
expected to be driven 14,390 miles per year, on
average, for example.

In these models, since price is not included, the
quantity of travel "demanded" is independent of price.
Another way of saying it:  increases or decreases in
the price of driving are not accounted for in the
models.


__________________________________
Do you Yahoo!?
Yahoo! Search - Find what you’re looking for faster
http://search.yahoo.com