Spanish steps.

Though modest in scale, this crisply detailed station in the suburbs of Barcelona evokes the great era of rail construction.

Suburban railway stations present a series of paradoxes: they deal with symmetrical tracks, but their environment is asymmetrical; they must have an intimacy of scale for the waiting traveller, but a monumentality related to their significance in the town and the trains which occupy them; they also highlight the divisiveness of the railway line while acting as crossing places and junctions. It is in the handling of these issues and their potential qualities - the transition from train to terrain and vice versa - that Bach and Mora have made an increasingly distinctive contribution. A previous station at Bellaterra was featured in AR May 1986.

The site at Sabadell is large. The architects' first move was to cover the railway tracks as far as Compte Jofre and Reina Elionor streets, thus allowing the station to make a link between them. The splayed wall in the rectilinear plan of the building is a vestige of the old street line and, by implication, the external concourse a vestige of the street. On this 'street' are two pavilions - a kiosk and a ticket office - and the entrance to the inner concourse is between them. The area gained by covering the tracks is used for parking and, on the far side, an elegant gatehouse which incorporates bicycle racks and parking ticket dispensers while signalling the presence of the building on the main street.

The three entry routes to the outer concourse are handled with exceptional skill and subtlety. The gatehouse is located at the junction of two sides of a little square and makes a geometric shift to rationalise the irregular site and establish a direct path to the concourse. It introduces the vocabulary of simple materials - brick, metal, glazed tiles - cleverly used and beautifully assembled to make an elegant modern language. And, in the external lighting through rooflights, there appears the first of a number of references to Aalto. From the two streets to the intimacy of the kiosks there is a major change of scale, partly accomplished by letting the entrance canopy run round the building at a constant height. On the elevation to Reina Elionor the canopy encompasses the long side window and naturally floats over the splayed wall. From the street there is a gentle rhetoric about this marking of the entrance at the narrow end of the splayed concourse. From the parking area, of course, it is a sensible indicator of how to get in. On Compte Jofre, the view through to the outer concourse above encourages you to read the first part of the ramp as part of the public pavement, albeit under the building canopy. This is reinforced by the ramp being extended beyond the end wall of the building and by a break in the upstand wall. Here is inserted an elegant steel and glass window that picks up the width of the street.

The outer concourse resolves the three entry routes. The breaks in the splayed wall blur the definition of the 'street' sufficiently to allow access to be made through it from the car park where the roof overhang is greatest. The glazing is not part of the formal composition - a bench appears to run through it, corners are frameless and a free-standing column completes the whole. It is a weakness that the door which faces the car park is not closer to that column and treated as part of the glazing rather than attached to the wall.

On the platform side of the building, the steel structure of the train shed is delicate, partly because the weight of the heavy and relatively crude concrete edge beam is balanced against it, tending to turn the roof up. The edge beam is a difficult area; it effectively frames the view from the waiting area and helps to reduce the scale of the shed to engage with the platform canopies; in theory it also reinforces the line of the entrance canopy, but this is seen better on the drawing than on site, where it looks a little clumsy, as if it might collapse and fall.

The stairs to the building are strongly reminiscent of those in Aalto's main auditorium building at Jyvaskyla but here a polished stainless steel cupping to the upstand takes the place of marble. The interior has a cool, almost Miesian precision. Materials appear not to be joined, but to be articulated assemblies or a series of layers. The roof of the main hall is higher than the entrance canopy and accommodation and interlocks two areas. The first is the continuation of the entrance between the two kiosks to the glazed screen giving access to the platforms; the second is a similar long rectangle on the line of the railway framed by the two lift shafts and marked by a large picture window on the axis of the tracks. The subsidiary spaces accommodate vending machines and public telephones.

The waiting area is a bridge over the tracks. Its picture window looks into the train shed, a glazed transitional space between passengers and destinations. The pronounced non-linear quality of the station is made very clear in this view up the tracks under the shed which, even in this little suburban station, revives memories of the great railway constructions of the past and evokes the romance of an important terminus.