The new Metrobus Maintenance Facility in Montgomery County suggests that there is life left in the old Modernist dictum that form follows function.

Designed by Mariani & Associates for the Washington Metropolitan Area Transit Authority (WMATA), the building was planned inside and out with the relatively straightforward requirements of its users in mind.

The result is a clean-lined structure that makes eminent functional sense, and in so doing pleases the eye. In achieving that secondary goal, the building reverses the altogether justifiable public image of a bus garage as a smoky, grimy, thoroughly third-rate place. The new building is spacious, colorful and clean, even after six months of heavy use.

"Our main aim was to create a work environment that makes people feel comfortable," says architect Theodore Mariani, president of the Washington firm. The building, located near Rockville Pike just north of the White Flint Shopping Center, was conceived as a prototype for six other garages WMATA expects to build in the region.

It is useful to point out that while the forthright functionalism of the Mariani firm works beautifully for this suburban bus garage, it performs poorly when applied to a much different problem; for example, a Mariani-designed vertical addition to the elegant, if tiny, Playhouse Theater building at 727 15th St. NW.

The reasons are fairly simple. The bus garage is situated on a large, open lot. It is not used, nor will it even be seen, by large numbers of the general public. Its relationships to the existing neighborhood are relatively straightforward. And its uses dictate the kind of analytical approach employed so successfully by Mariani. Functionalism, after all, is a credo born in the early days of the Modern movement, out of admiration for industrial processes and architecture.

Downtown, the situation changes dramatically. The problem was how to add on to a distinguished structure that sits between noteworthy older buildings. Here the issue of context, of fitting the new in with the old, becomes paramount, and the Mariani scheme for a modern building with horizontal windows and balconies insensitively fails to address this issue.

But the bus building is a fine piece of work. It is tucked into a corner of a 17-acre site near Rockville Pike, most of which was paved to provide parking for 250 buses.(This caused an unfortunate problem, but more on that later.) Satisfying simplicity is the building's main virtue on the outside.

Long and low, sheathed with white-colored insulated metal panels rounded at the corners (to minimize collision damage), and distinguished by rows of red-painted doors to the repair bays and vertical skylights, the building is what it is, no tricks, no frills and no apologies.

Inside, the design is admirably clear-headed and surprisingly exuberant. The most arresting space is the long open room with 16 repair bays--wonderfully light-filled, thanks to the northern exposure of the skylights. Structural and mechanical systems were left entirely exposed inside the shed-like structure, but they were painted. Yellows, grays, oranges and reds play invitingly against the striking deep-blue color of the structural steel. As a result what could have been an unattractive maze of steel beams, ducts, pipes, catwalks and reels for engine and other lubricants is instead a visual delight, a colorful celebration of the machine esthetic.

The building also contains a mezzanine level for bus drivers and administrative functions--spartan but serviceable--and a wing devoted to fare collection, safety inspections, and vacuuming and washing the buses. The latter space, though pretty much what you would expect, is again a model of color-coded efficiency.

Another of the impressive things about the building is the evidence all around that things were intelligently planned and well built. Many are the good designs that have been desecrated by false economies and poor craftsmanship during construction, but this one was a really tight ship from beginning to end.

Mariani, a structural engineer as well as an architect, attributes this to the unusual fact that instead of simply handing over their drawings for someone else to execute, the architects were permitted to supervise the entire construction process. The result, he says, was an economical job done on time and with great care. (The principal contractor was Kora and Williams Corp. of Rockville.) Mariani believes the separation of the design work from the actual construction is one of the main reasons for a general decline in the quality of the building crafts. With the evidence of the Montgomery Division bus garage to back him up, he makes a solid case.

The one distressing aspect of the project is the brick wall that was erected to screen the vast bus parking lot from public view along Nicholson Lane. The wall is long, boring, made from the wrong material and it doesn't even do the job. Instead of hiding the buses, the wall offers a teasing glimpse of their tops. It is as if the architects' philosophical nerve somehow deserted them at this point.

What actually happened, recalls architect Reginald Cude, who was principal-in-charge of the project for the Mariani firm, was that in response to concerns from developers and other neighbors of the project, public agencies in Montgomery County insisted that the wall be built, and built of brick.

The fears are understandable--who wants 250 buses parked in the neighborhood?--but the solution was tepid and conventional. And it isn't as if this particular fast-changing neighborhood were made up of rolling farm land or single-family suburban homes. When all is said and done there is a certain hard-nosed poetry to the sight of a massive fleet of buses and, after all, they are necessary and they are there. A more inventive approach would have found a way to celebrate this muscular fact.

Well, it is something for the WMATA folks to consider as they build the rest of these garages with their giant parking lots. In other respects both client and architect are to be lauded for tact and skill. There are places and building types where the Modernist ideal of functionalism still works, and this is one of them.

The happy rejuvenation of Baltimore's Penn Station, discussed in this column on July 16, was preceded by work done under a station refurbishment program that took place during 1976-77. The Washington office of Harry Weese & Associates (Harold L. Esten, architect in charge) was responsible for the design aspects of this program, totaling $225,000 for the Baltimore station.

The $5 million restoration now nearing completion has been accomplished under the design supervision of the Washington office of Skidmore, Owings and Merrill. An architectural joint venture company made up of the Leon Bridges Co. of Baltimore and Robert J. Nash of Washington did substantial research on the restoration and prepared detailed construction drawings. CAPTION: Picture, Repair bays in the new Metrobus Maintenance Facility just north of White Flint Mall on Rockville Pike. Copyright (c) by Harlan Hambright