Railway Stations as Edges

"Edges are the linear elements not used or considered as paths by the observer." [Lynch p.47]

However, "Edges are often paths as well...the circulation image seemed to be the dominant one. The element was usually pictured as a path, reinforced by boundary characteristics." [Lynch p.65]

Not to consider Lynch contradicted himself, I think what he tried to explain was that: from the observer's point of view, there are some linear elements which are clearly Paths (eg. Key Bridge in DC), while some are clearly Edges (water line of the Potomac River). But there are some that possess the characteristics of both Path and Edge.

Characteristics of Edges
- may be boundaries between two kinds of areas
- lateral references rather than coordinate axes
- visually & spatially penetrable / impenetrable
- uniting seams / isolating barriers
- continual / fragmented
- visual & spatial prominence
- directional

Railway lines are observed as edges by people not on the train. In many cases, they are visually and spatially impenetrable unless they are elevated as well as constructed in a way that they have better looking. While subways, which are buried in the ground, clearly show no characteristics of Edges.

Railway stations are segments of the railway lines. They are also observed as edges in the city. They are usually adjacent to public squares, open spaces or roads where the linear form of the station will give a significant boundary to the adjacent space. However, such edges may become urban barriers for pedestrians and vehicles if they are not well designed.

The Bijlmer ArenA Station in Amsterdam, designed by Grimshaw Architects, is a good example of converting an urban barrier to a uniting seam between the two sides of the station. Plus it is architecturally appealing.

For subway stations, which are the connections between the buried paths and the upper ground, are the mere opportunities to express the edge qualities through the superstructure of the stations. As many subway alignments follow major corridors in the city, the edge expression can work with the paths to enhance each other.

However, in a dense urban core where subways usually serve, such expression become too expensive to achieve, and not quite fit in the context. It is reasonable to keep a modest gesture for the stations and to develop a more extensive underground network in urban core.

While if the stations are located outside the urban core where land pressure is not very tight, there are more potential to build a visually prominent architecture for the stations.