Given events in Canadian transportation policy in recent months, it's difficult to escape the impression that the economists have taken over the asylum. The market-oriented reforms in the 1986 deregulation white paper were the first serious outbreak of rational thought in this area. But they have been followed lately by a raft of even more subversive suggestions:

Late this year or early next, Transport Canada will start charging airlines substantially higher minimum landing fees at major international airports, with surcharges for peak periods, as a means both of rationing demand for landing slots and paying for airport operations. Similar levies will be imposed on marine transport.

Transport officials are also considering charging truckers and motorists for the use of highways via a toll system, though the government has issued the usual denials. But Ottawa isn't the only one looking at the idea: Ontario is studying a scheme using electronic scanners to read computer chips embedded in a car's windshield.

The federal government may be chivied into privatizing the airports. The original plan announced in 1987 was to transfer management to local airport authorities set up by the municipalities. But following the precedent set with the private development of Toronto's new Terminal 3, the way is clear. Three groups have unveiled rival bids for the rest of Canada's busiest airport, to force the issue out in the open.

There is a growing consensus in the airline industry in favor of Canada and the U.S. extending cabotage privileges - the right to fly between two cities in the same country - to each other's carriers: in effect, free trade in air travel. This will be a main item for consideration by the federal government's new task force on international aviation policy.

None of these, except perhaps the last, is particularly novel in world terms. But for Canada, they are the stuff of revolution. We are well on our way, at last, to a system free of the monopoly, statism, deficits, price-fixing, cross-subsidization and protectionism that have historically bedeviled Canadian travelers and shippers. The thrust of these latest reforms is to make each transportation sector - road, rail, air and water - pay its own way. Consumers would then be free to choose, depending on the true costs and benefits of each, without the influence of subsidy.

There remains one exception to this generally encouraging trend. Sometime in September, a Quebec-Ontario task force will make a preliminary assessment of plans for a high-speed rail link between Windsor and Quebec City. At the moment, there are two proposals, both from Montreal-based firms, both probably wildly underestimating costs and both looking for subsidies. Bombardier wants to run trains at 300 km/h on special tracks at a cost of $5.3 billion, almost a third of which would come from government. Asea Brown Boveri's alternative would run slower and cost less: $3 billion, it says, including a ''minimum'' subsidy, since it would use existing tracks.

And VIA Rail (remember it?) says whichever plan is chosen, it wants a piece of the action. The Tories may have cut VIA's subsidy in half (to a paltry $350 million), but the Crown corporation sniffs new opportunities in high-speed rail. VIA President Ron Lawless, who just months ago was telling Canadians that ''romanticism must give way to realism'' about the railway, now urges Canadians to dream the dream again.

A high-speed rail system would be ''a new task for Canada,'' he says, one that would rekindle the ''nation's consciousness.'' But he warns this will require significant government money: the initial rate of return would not be sufficient to attract private investors. ''So if they make a business decision, I guess they would be saying no high-speed rail.''

Which is another way of saying it shouldn't be built. The sole justification for subsidy would be to reduce the congestion and pollution stemming from other modes of transport, owing to the failure to price them in line with costs. But with those implicit subsidies now being removed, that argument falls to the ground.

Even were they to remain in place, that would be an argument for subsidizing the price of a ticket, not for offering huge up-front grants for a service which, for all we know, no one may want. It is train traveling we might wish to subsidize, not track laying. At least, if economics and the public good, rather than last-spike photo opportunities, are the chief consideration.

The only reason these latter-day National Dreamers are asking for subsidy is that they think they can get it. The trouble is, they're probably right.