Driving to Washington Dulles International Airport, I always look studiously at the slick buildings and rolling landscape along the highway, inevitably wondering how many new projects have sprung up since the previous journey.

For several years, the corridor between Tysons Corner at the Capital Beltway and Dulles has been among the hottest real estate growth areas in the region. If you asked a commercial real estate broker where the action was, he or she would invariably point to Northern Virginia, west of Washington.

Similarly, I-270, stretching northwestwardly from Bethesda to Frederick, Md., was the "hot" corridor of the 1970s. It is still relatively so, but increasing traffic congestion and overburdened public facilities are somewhat dampening the economic flames that characterized the previous decade.

The Dulles and I-270 corridors typify a species of suburban development that was first given life by national road-building policies adopted in the 1950s. The federal government, along with the states, mounted an unprecedented, multi-billion-dollar interstate highway program. Its ambitious goal was the creation of a nationwide network of limited-access high-speed highways and urban beltways that would carry traffic nonstop between and around, rather than through, major U.S. cities.

Not only would such highways accommodate interstate and intercity traffic (seen 30 years ago as vital to effective civil defense, as well as to commerce), they also would serve commuters traveling between suburban home and urban workplace.

Of course, it didn't take long for planners, developers, local governments and corporate executives to realize that urban workplaces could be moved to the suburbs. For these new highways promised seemingly unlimited amounts of acreage, desirable road frontage, and convenient access for employes who could live in newly developing, not-too-distant subdivisions.

Like commercial strips, highway corridor land, with its use and potential value established by zoning, could be subdivided into parcels and developed independently by individual owners.

But development along limited-access highways took a form different from commercial strips. Zoning often prescribed that parcels be relatively large in size -- usually several acres -- to accommodate large-scale structures and on-site parking, while still preserving substantial amounts of open "green" space. A parallel network of roads, accessible from highway interchanges, had to be built to serve the highway frontage and its hinterland.

At the same time, many jurisdictions decided to exclude so-called "heavy" industry -- transformation of natural raw materials, chemical processing, combustion or other operations yielding noxious environmental wastes -- from these corridors. Instead, they wanted their beltways and certain radial highways to be flanked by "clean" industry -- research and development institutions, light manufacturing, warehouse and distribution centers and corporate headquarters.

Companies were expected to build handsome buildings while employing lots of local residents. Modern corporate architecture presumably would blend with pastoral landscapes and tastefully display company names and logos, thereby advertising themselves to thousands of motorists passing by each day.

Thus the pattern of development was clearly etched. Today, throughout the United States, thousands of miles of suburban highway exhibit similar characteristics, looking much like the road to Dulles.

Along these highways, most buildings stand in isolation, sometimes fronting and parallel to the highway, sometimes placed askew to it at apparently arbitrary angles. Buildings may sit close to the highway right-of-way, but more frequently, they are set back, sometimes several hundred feet. This tactic actually can increase the amount of time that the building remains in a passing driver's field of vision, providing a better opportunity to form a lasting impression and possibly to read the name of the company. It also reduces the ambient highway traffic noise for occupants of the building.

Building size and massing vary widely from low and sprawling flat-roofed boxes to high-rise towers. Materials range from the utilitarian and unpretentious corrugated metal or painted concrete block to the elegant and expensive granite, marble, cast stone or reflective glass. Brick and precast concrete probably are the most commonly applied veneers.

Although architectural styles and motifs can be diverse, most buildings nevertheless appear to be composed of rectilinear solids sheathed with ribbon-windowed, panelized curtain walls of varying proportions and colors. Occasionally, special inflections occur at corners, parapets and entrances.

Some buildings have a front facing the highway, while many others appear to have turned their backs to it. A few buildings have two fronts. One may be designed and scaled for the highway, in effect a formal and mostly public front. But there also may be a front for the service road and parking lot from which people actually approach and enter, opposite the highway.

The motorist experiencing these episodic, linear industrial parks at 55 miles per hour might ask what they all add up to. Not too much, I would suggest.

Undoubtedly, high-tech highways make economic sense locally by augmenting employment opportunities and tax revenues. But from a design point of view, they rarely exceed the sum of their parts. Being so separated from one another, most buildings, no matter how artfully designed, merely become three-dimensional billboards, usually surrounded by parking lots.

Workers in most of these buildings are wholly dependent on the automobile for going anywhere or doing anything during lunchtime. The absence of retail services within walking distance means getting in a car and driving elsewhere -- probably a shopping center -- to find a restaurant or a drugstore.

Clearly, zoning and transportation policies have not led to ideal settlement patterns, lovable architecture or uncongested traffic. But in a free-enterprise system driven by incremental market forces, could it be otherwise? Only if the "system" were to adopt more aggressive policies regarding land use, site planning and design.

Not surprisingly, development along most limited-access highways is subjected to very few meaningful design standards. Typically, there is no consensus about setbacks, relationships between buildings, building massing or the mixing of uses. Few precedents exist for the aggregating of parcels or clustering of separately owned buildings so that together they might add up to something visually grander, more unified and possibly capable of supporting affiliated services.

One wonders if there isn't some way for each separately developed structure to participate in a larger order or formal framework that could exist at the scale of the highway itself.

NEXT: Ceremonial streets.