Douglas N. Schneider Jr., 46, chief maker of transportation policy for the District of Columbia, stares out his fifth floor office window at the rivulets of traffic in Pennsylvania Avenue. He speaks gravely, choosing his words with care, a model of bureaucratic imperturbability.

"The single commuter, alone in his car," he says, "comprises the lowest and worst use of the urban transportation system." His voice is neutral, his face devoid of emotion.

But behind the subdued manner and even-featured Cary Grant countenance seethes an intense and sometimes smoldering hardliner, a kind of domesticated transportation renegade who wants to stand the preeminence of the almighty automobile on its head.

He wouldn't put it quite that way, but the practiacl effect of Schneider's policy goals is to make it as inconvenient, unpleasant, disruptive and expensive as possible for what he calls drive in the District of Columbia and to force him onto public transportation or other ways to travel such as car pools, walking and riding a bicycle.

If you're a car commuter, you've probably already noticed the noose tightening - residential parking bans, bus-only lanes on major streets during rush hour, the 12 percent sales tax on commercial garage parking.

Things may get together. If Schneider has his way in the future, ticketing of illegally parked cars will be greatly intensified by a small army of civilian ticket writers and subsidized parking rates for federal government employes will be eliminated.

Schneider is in a position to make his intentions felt. He enjoys the confidence of Mayor Walter E. Washington and the respect of federal government members of Congress and the D.C. City Council.

He is the mayor's alternate on the Metro board and a key sharper of the city's policy on bus-rail transit. He is also chairman of the influential transportation planning board of the Metropolitan Washington Council of Governments.

Schneider, a Nebraska-born attorney, also carries his convictions into his personal life. He owns a car but rides the bus to work and has been known to stand on the street in front of his home in Glover Park to stop speeding youngsters in hopped-up jalopies and give them a memorable tongue lashing.

There are good reasons for cracking down on cars, Schneider said in the course of two interviews recently. For too long, he said, the automobile driver has been overprivileged, over-subsidized and overpampered, while the public transit rider has been pushed aside.

The result is a noisy, filthy city, he says, cluttered with under-used passenger cars filling up residential and commercial parking spaces, jamming major routes with nonessential traffic and impeding the flow of public buses, emergency vehicles and legitimate commercial traffic.

"So we've set out to discourage this," Schneider said, "and give the commuter a better alternative - improved public transit."

It's rudimentary carrot-and-stick philosophy - punish the commuter for using his car and reward him for using public transit.

Schneider acknowledges that the present transit system is not always rewarding and that the new subway network in fact imposes some additional hardships, such as the payment of double fares for commuters transferring from bus to rail. But he contends these are temporary problems, part of the growing pains that will disappear as the new system approaches maturity.

In its broadest sense, Schneider says, the economic burden of a city transportation system must be shifted from the mass transit user to the private auto driver.

Traditionally, he said, "the rate making process for public transit was geared to having the rider pay the operating cost plus a profit for the owner - while the automobile driver was getting all kinds of breaks and subsidies . . . The transit rider - the poorer guy who could least afford it - was being charged more and more. It was all out of balance."

Now that balance is beginning to shift, Schneider said. With the transit system here now publicly operated by the Washington Metropolitan Area Transit Authority, transportation analysts estimate the typical bus or train rider pays about half the true cost of the ride at the fare box and the other half is paid by regional tax subsidies.

"From a social point of view," Schneider said, "it is much more humane to subsidize mass transit and put penalties on the automobile driver."

To Schneider, the urban freeway has become the ultimate symbol of irrational transportation planning.

"What sense does an urban freeway make?" he ssked. "It takes up space in an already crowded area. It removes land from the tax base. It's ugly. It destroys the city esthetically. It creates pollution. It cuts off urban dwellers from city services.

". . . But most important, it fails to accomplish its objective. It just generates more cars. It may move the congestion around a little bit, but it sure as hell doesn't solve the problem."

Schneider likes to quote a District government study published in the early 1960s at the height of the city's profreeway era, which Schneider says reflects the coldly pragmatic and "antihuman" transportation philosophy of that time. The study describes the intended effect of the now abandoned "inner loop" proposal for the city's freeway system:

The plan (would) erect a wall around the downtown area . . . This 200-foot roadway will dam the city core while allowing crosstown traffic to avoidit . . .

"It will ease the burden on existing streets, protect inlying residential neighbourhoods, clear a few slums, relieve some population pressure in the crime-ridden second (police) precinct . . . and advance the coming of the automobile age."

That says Schneider, was the conventional wisdom of the day - "you know, get rid of the people and the crime. Kind of like Carthage."

That mentality gradually faded in the early 1970s with growing popular antifreeway pressure, shifts in federal policy toward mass transit, the advent of District home rule and the reorganisation of the city's old highway and motor vehicles departments into a single transportation department.

Mayor Washington appointed Schneider to head the new department in July 1975, but Schneider had already been at work in the mayor's administration as transportation systems coordinator since early 1973, quietly helping to shape new transit policy.

Before that, he was executive director of the old Washington Metropolitan Area Transit Commission, which, at that time regulated and set fare rates for the area's various privately owned bus systems. While there, Schneider helped mobilize local government response to the growing financial woes of the bus lines that resulted in their public takeover in 1973 by Metro.

With the support of a generally sympathetic District Building and City Council, Schneider has presided over a gradual tightening of restrictions on private auto use in the city: bus-only lanes on major streets during rush hour, a commuter parking ban that now covers more than 800 residential blocks, squeezing up to 12,000 suburban cars off the streets each day and forcing their drivers to pay stiff commercial garage rates or leave their cars at home and ride the bus.

Short-handed police have enforced the ban only spottily, and commuters have begun filtering back into some of the restricted blocks. Schneider is the first to acknowledge $5.9 million in the city's 1979 budget for a Department of Transportation program for ticketing, towing, impounding, booting and adjudicating illegally parked cars as a supplement to police efforts.

Enforcement would be swift and stern - 50 specially trained civilian ticket writers would swarm through residential areas, issuing 75 tickets each a day. Twenty-five trucks would tow 112,500 cars parked in tow-away zones each year, charging $25 on each ticket, plus a $50 towing fee and a $3-a-day storage fee. Additional crews would slap 20,000 Paris boots on scofflaw vehicles a year, almost triple the number now booted by police.

Schneider contends that although the program would cost $5.9 million in its first year, it would generate $20 million in fees and ticket revenues.

"This is the only way the residential parking program (commuter ban) will work," he said. "It's tough for the police to put their limited resources out there, so I think our program will work."

Schneider constantly emphasizes that he is not simply "anticar" but is opposed to the "single commuter alone in his car" when group travel by public transit car pooling or van pooling is less wasteful in this age of limited resources.

"I think we have an obligation to avoid cars in the city and take public transit," he says.

Besides, he says, "when you think about it, driving a car is about the most boring thing in the world . . . On the bus or train, you can read or do work. You get in some walking time between your home and the bus stop . . . I really feel freer."