"(Buses and SUVs are so small as to ignore)." With respect to road maintenance expenditures, it appears.

Alan - In a recent discussion with a guy who works for OKC, he commented somewhat the opposite.

Some background. There is a move to save the railyards just south of the old Union Station. The Station is a historical landmark, but the railyard is not. Other communities around OKC want to save the railyard, but OKC has not been motivated to take up the fight to save them, because the need to replace the old and possible dangerous overhead section of I-40 just south of downtown is their greatest need, and that project is underway or virtually underway. The discussion with the guy from the City was to get their opinion, informally and unofficially, about what the City needed. He opined that the City most needed busses to meet their current needs and the monies to keep the streets where those busses would run in good repair.

If the system were built out as the exurban cities want, this would entail a massive number of miles - I would guess in excess of 100 miles of improved rail - with a limited ridership. The City has considered many other alternatives, and does not favor the commuter rail, at a high cost, much of which would be borne by the residents of the City, just to dump a bunch of folks who do not live there downtown, with most wanting to go someplace else which the existing and planned facilities cannot handle. If it is crammed down the City's throat, which I do not see, it will cause massive expenditures for the improvements to the streets to facilitate the use of busses.

Thus, my question - is your quote above accurate for this sort of circumstance?

It may be theoretical, since I do not think that the cities who favor the plan will be willing to raise their taxes sufficiently to handle their share of the burden, but "stimulus package" funds might take enough of that burden off the exurban cities for the COG to try to impose the system on OKC, like it or not. Using Dallas system, DART, as an example however, 83% of the sales tax revenues which support DART are spent on operating expenses (for 2004, the latest year I could find). http://en.wikipedia.org/wiki/Dallas_Area_Rapid_Transit

There are lot of variables to consider unfortunately. Rather than try and model it, I am wondering if it would simply be easier to compare roads that prohibit trucks (like some parkways) and roads that don't, and use this to try and get a handle on how the maintenance requirements are increased by the presence of trucks.

I am thinking that your best best is to find an engineer at a state highway department who can give you some real-life and uptodate numbers to work with, and help to choose some good roads to use as your sample.