Pedagogical Sketchbook

Copyright 1988-2000 Robert Hotten/Plantation Ltd- All rights reserved



Walkabout II.B. Perceptions

Axial Dynamics

"A house is a machine for living in..." (Corbusier, 1923)

"But I thought that all that functional stuff had been refuted. Buildings aren't machines." (Student)

"You haven't understood. The building isn't the machine. Space is the machine." (Nick Dalton, Computer Programmer at University College London, 1994)

(Hillier, 1996)



The essence of urban form is that it is spatially structured and functionally driven. Between structure and function the notion of intelligibility, defined as the degree to which what can be seen and experienced locally in the system allows the large-scale system to be learnt without conscious effort. Structure, intelligibility and function permit us to see the town as social process, and the fundamental element in all three is the linear spatial element, or axis.


In common urban space, the most familiar property of the axis is that it usually passes through a series of convex spaces...

They... towns and buildings... are as they are because we can use the convex and axial superstructures to provide visual extensions to our metric presence, and through them make available locations to which we might wish to go...


This pedagogical sketchbook describes the axis as symbol and as instrument.


Symbolic axiality in urbanism

Properties that seem to be associated with the axis as symbol rather than instrument

1. The degree to which axiality is "just about" rather than filled out into continuously fat spaces.

"Just about axiality" is the consistent property of the spatial structure of the city. Where no just about axiality exists, then often two just about axes take their place.

There is for the most part a "two-line-logic" in that if you pass down a line that you can see from the main grid, the next line will take you either out of the back area again or to some significant spatial event- say a larger piece of space or a significant building- within the back area. This means that wherever you go, there is usually a point from which you can see where you have come from and where your next point of aim might be. This is the opposite of the labyrinthian.


2. The degree to which there is a few-step logic throughout the system rather than a one-step logic in some parts combined with a many-step logic in others.

"Two step" logic of "just about" axial lines

...when you are going from one "place"- be it a slightly larger space, or a major line, or a key building- to another, then there is always likely to be if not a point from which both original destination can be seen then at least a section of line from which both are visible. Since we can also see that each line passes through a series of convex spaces, and that each convex space, however small, will usually have building entrances opening onto it, we can see that the axial organisation and convex organisation of space combine with the location of building entrances to create a consistent type of pattern yielding both intelligibility and order out of what might otherwise seem a formless aggregation of buildings. is easy to see that the City has everywhere if not a two-step axial logic then at least a few-step axial logic.


3. The degree to which strong and weak axiality is related to the entrances of buildings.

Here [Versailles] we find three powerful axes striking the palace head on... In terms of natural movement, the Palace acts as a negative attractor...

The effect of these apparent rules about how buildings relate to open space is to create two "interfaces". First, there is a close relation between those within the building, and those outside. Second, there is a natural mingling between those who are using the space outside the buildings, and those who are passing through.


4. The angles of incidence of axial lines on building facades.

However, when we compare the two levels at which we find this two-line-logic, there is a geometric difference which we can summarise in a simple principle: the longer the line the more likely it is to strike a building at an open angle, the shorter the line, the more likely it is to strike a building at a right angle.



Instrumental axiality in urbanism


Teotihuacan, concerned with social reproduction, is dominated by symbolic monuments and ceremonial buildings...

Social reproduction, we might say, requires symbolic forms of space, social production instrumental forms of space...

It is through the use of axis as symbol that forms of social power most naturally express themselves through domination of the urban landscape. This is fundamentally why we have two types of city: the common type of working city, and the more exceptional type of city specialised by the need to reproduce the formal structure of society.


Other aspects of axiality


Facade isovists and axiality


It is an empirical fact that, regardless of their relative prevalence in geographical or planning texts, by far the great majority of towns and cities in human history display more structure than order...

There is a simple reason for this, centered about the relations between space, form and time. Unlike urban space structures, which are asynchronous because they require the passage of time required for movement in order to see them piece by by piece, building facades are , in their very nature, synchronous. They are intended to be read and understood all at once. They, therefore do not require time for their understanding.

Order, we might suggest, is as prevalent over structure in built forms as structure is prevalent over order in space...

It is clear that every facade will be partly visible from certain points in urban space and wholly visible from others. Both sets of points form a shape, defined by all that can be seen from the facade. We can draw both shapes, and call the first "part-facade-isovist" and the second the "full-facade-isovist.



"Just about" axiality is the product of this minimalist approach to the problem of global form in urban layouts. Even more strikingly, it is the means of linking the local "place" to the global structure and through this of achieving that compression of scales- the sense of being in a locally identifiable "place" and part of a much larger "city" at one and the same time and by the same spatial means- which is the distinctive excellence of good urban design...


In short, the logic of the symbolic axis is in its way as consistent as that of the instrumental. Its object is not to organise a pattern of movement and through this generate encounter, but to use the potential of urban space for another kind of emphasis: the communication throughout space of the symbolic importance of certain buildings or locations.




Links to other Haptic Experimental Resources


U.C. Berkeley, College of Environmental Design

Technosphere AI





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Robert D. Hotten, MLA Architect