What would New York City be without its taxicabs, its crosstown buses and its subway system?

Manhattan's urban image is fashioned by those ubiquitous yellow vehicles monopolizing its streets no less than by its soaring real estate. For both residents and visitors, Manhattan insists that you remember its graffiti-covered subway cars, colorful advertisements above subway car windows, theater posters on station walls, slightly oily turnstiles, subterranean forests of steel columns, hot-dog stands and iron-railinged subway entrances erupting periodically from sidewalks.

And, as if visual stimuli were inadequate, there are plenty of auditory and olfactory sensations. Squealing train brakes, screeching wheels or expresses roaring through dimly lit stations test your eardrums. Indescribable odors linger in passageways whose hygiene and safety seem questionable.

Compared with New York, Washington's transit systems are squeaky clean, but they seem to contribute much less to the capital city's image. Despite Metrorail, Metrobuses and thousands of taxis, Washington remains a commuter city where private automobile transportation predominates.

Consider Washington's taxis, which do little for Washington's image. They lack the consistent symbolic color that characterizes New York's fleets. D.C.'s "Yellow" cabs are really pumpkin orange and black, while others are beige, red, black, white, blue, green and everything in between.

The Metrobus network is far-reaching, and its vehicles -- unlike the taxis -- are graphically coherent. Dominantly silver and metallic, the buses wear bands of red, white and blue stripes matching the flag-like red, white and blue bus-stop markers. But, interestingly, some buses' stripes are inverted -- blue on top, white, red at the bottom -- as are the stop markers.

Also note that these patriotic graphics and chromas are shared with hundreds of Postal Service trucks and with proliferating, reconstructed Exxon stations.

Of course, Washington's pride and joy is its subway, Metrorail. Requiring more than three decades to design and build, Metrorail makes up in elegance and comfort what it lacks in geographic coverage and big-city moxie.

Metro's map shows clearly that the subway system primarily transports commuters from the outer layers of the city and suburbs to the central business district and federal government core. Its vaguely radial network serves distinct population corridors and activity nodes along the way (such as Van Ness and the Eastern Market). A combined car/bus/rail transit strategy allows a commuter to walk, take a bus, or drive to a convenient point on a subway line and then speed to downtown destinations.

The result, it was hoped, would be reduced traffic congestion and parking in Washington's core and along its major arterial roads. Further, Metro would serve National Airport and carry tourists to and from the Mall area. It achieves the latter but is only marginally successful in serving airport passengers with baggage for whom the detached station elevated over the parking lot is extremely inconvenient.

Unfortunately, Metro's lines do not correspond with the travel "desire lines" of many Washingtonians. If you live in one of the several wide wedges of space between lines, it may be difficult to use the subway regularly because of the time required to travel by bus or on foot to the nearest subway station. If you have to use your car to reach the transit system, you are likely to continue driving to your ultimate destination, especially with parking lots at outlying Metro stations filling up very early each weekday morning.

To go from Bethesda to College Park, from Fairfax to Alexandria, or from Georgetown to Walter Reed Hospital, Metrorail won't do. Metrobus will, but bus travel can be lengthy and time-consuming, with indirect routes, transfers and irregular schedules, particularly during nonrush-hour and weekend periods. As a result, many Washingtonians who might otherwise choose to travel by subway or bus are forced to drive their own cars.

Like New York or London, Washington could have made its subway follow a lattice, rather than a radial, pattern. A lattice network would have provided more flexibility in point-to-point travel, with or without going through downtown. But D.C.'s density is too low: Metro would not have attracted adequate levels of ridership during rush-hour periods when commuters are mostly converging on or diverging from the central city.

And of course, there's the Georgetown omission. Perhaps some day that mistake will be rectified. At the same time, Washington might be ready for a loop or circumferential line.

Metro's greatest success may be its architectural design and occasional positive effect on real estate development, not its service pattern or its impact on Washington travel habits.

Guided by Chicago architect Harry Weese, a team of designers and engineers created visible system elements -- platforms, stairs, railings, vaulted ceilings, canopies and skylights, signs, floor paving, lighting and detailed hardware -- that are stylish, attractive, durable and reasonably functional.

Most important, the kit of parts was employed consistently throughout the system. While accommodating variations and adaptations to suit specific site and station conditions, this strategy imparts visual coherence to the entire network. Thus, the architecture itself becomes the system logo, the recognizable and memorable cachet for Metro, as much as the letter "M."

Metro's stations remain remarkably immaculate. Its escalators, unlike its farecard machines, work most of the time. The silver trains accented with brown (what happened to red, white and blue?) are relatively quiet and brightly lighted. Car interiors are pleasant enough, although they will win no design or comfort awards. Graphics are clear and easily read; only inattentive riders would miss their stop or train.

Underground, the free-floating platforms disengaged from the coffered concrete vaults create a distinctly futuristic, high- (but not too high-) tech look. Beneath your feet, the red hexagonal tiles, concrete coping at platform edges and recessed lights (they flash whenever a train is about to arrive) seem to be the right blend of visual slickness and engineered toughness.

Metro is a handsome addition to Washington's infrastructure and streetscape, but it has not transformed them. This could occur only with greatly increased development and density along its lines and at stations.

Metro came late in Washington's urban growth period. It traverses parts of the city with already established land-use patterns, zoning, buildings and streets. Therefore, its potential as a major determinant of the city's ultimate shape, skyline and occupancy is very limited except in those areas that are undeveloped or redeveloping such as New Carrollton, Rockville, Silver Spring and Ballston.

Despite the billions of dollars invested in the Metrorail and Metrobus systems, and despite Metro's catalyzing of real estate investment, it is wishful thinking to believe that the supremacy of the automobile will be compromised. Too many Washingtonians live too far apart and travel in too many directions for mass transit to become the primary means of intracity travel.

Increasing numbers of citizens live and work in suburban Washington, further obviating any regular need to use Metro. How often they express their preference for frequenting places -- offices, stores, restaurants, movie theaters, or shopping centers -- because they can find ample parking space.

Washington's suburban/urban schizophrenia, along with its driving habits and traffic jams, are here to stay.

NEXT: Zoning and land use.