A Penn

NATURAL MOVEMENT - OR, CONFIGURATION AND ATTRACTION IN URBAN PEDESTRIAN MOVEMENT

Existing theories relating patterns of pedestrian and vehicular movement to urban form characterise the problem in terms of flows to and from ‘attractor’ land uses. This paper contains evidence in support of a new ‘configurational’ paradigm in which a primary property of the form of the urban grid is to privilege certain spaces over others for through movement. In this way it is suggested that the configuration of the urban grid itself is the main generator of patterns of movement. Retail land uses are then located to take advantage of the opportunities offered by the passing trade and may well act as multipliers on the basic pattern of ‘natural movement’ generated by the grid configuration. The configurational correlates of movement patterns are found to be measures of global properties of the grid with the ‘space syntax’ measure of ‘integration’ consistently found to be the most important. This has clear implications for urban design suggesting that if we wish to design for well used urban space, then it is not the local properties of a space that are important in the main but its configurational relations to the larger urban system.

From Isovists to Visibility Graphs: A Methodology for the Analysis of Architectural Space

An isovist, or viewshed, is the area in a spatial environment directly visible from a location within the space. Here we show how a set of isovists can be used to generate a graph of mutual visibility between locations. We demonstrate that this graph can also be constructed without reference to isovists and that we are in fact invoking the more general concept of a visibility graph. Using the visibility graph, we can extend both isovist and current graph-based analyses of architectural space to form a new methodology for the investigation of configurational relationships. The measurement of local and global characteristics of the graph, for each vertex or for the system as a whole, is of interest from an architectural perspective, allowing us to describe a configuration with reference to accessibility and visibility, to compare from location to location within a system, and to compare systems with different geometries. Finally we show that visibility graph properties may be closely related to manifestations of spatial perception, such as way-finding, movement, and space use.

Space Syntax And Spatial Cognition: Or Why the Axial Line?

Space syntax research has found that spatial configuration alone explains a substantial proportion of the variance between aggregate human movement rates in different locations in both urban and building interior space. Although it seems possible to explain how people move on the basis of these analyses, the question of why they move this way has always seemed problematic because the analysis contains no explicit representations of either motivations or individual cognition. One possible explanation for the method’s predictive power is that some aspects of cognition are implicit in space syntax analysis. This article reviews the contribution made by syntax research to the understanding of environmental cognition. It proposes that cognitive space, defined as that space which supports our understanding of configurations more extensive than our current visual field, is not a metric space, but topological. A hypothetical process for deriving a nonmetric space from the metric visibility graph involving exploratory movement is developed. The resulting space is shown to closely resemble the axial graph.

Encoding Natural Movement as an Agent-Based System: An Investigation into Human Pedestrian Behaviour in the Built Environment

Gibsons ecological theory of perception has received considerable attention within psychology literature, as well as in computer vision and robotics. However, few have applied Gibsons approach to agent-based models of human movement, because the ecological theory requires that individuals have a vision-based mental model of the world, and for large numbers of agents this becomes extremely expensive computationally. Thus, within current pedestrian models, path evaluation is based on calibration from observed data or on sophisticated but deterministic route-choice mechanisms; there is little open-ended behavioural modelling of human-movement patterns. One solution which allows individuals rapid concurrent access to the visual information within an environment is an ‘exosomatic visual architecture’, where the connections between mutually visible locations within a configuration are prestored in a lookup table. Here we demonstrate that, with the aid of an exosomatic visual architecture, it is possible to develop behavioural models in which movement rules originating from Gibsons principle of affordance are utilised. We apply large numbers of agents programmed with these rules to a built-environment example and show that, by varying parameters such as destination selection, field of view, and steps taken between decision points, it is possible to generate aggregate movement levels very similar to those found in an actual building context.

Instrumenting the city: developing methods for observing and understanding the digital cityscape

We approach the design of ubiquitous computing systems in the urban environment as integral to urban design. To understand the city as a system encompassing physical and digital forms and their relationships with peoples behaviours, we are developing, applying and refining methods of observing, recording, modelling and analysing the city, physically, digitally and socially. We draw on established methods used in the space syntax approach to urban design. Here we describe how we have combined scanning for discoverable Bluetooth devices with two such methods, gatecounts and static snapshots. We report our experiences in developing, field testing and refining these augmented methods. We present initial findings on the Bluetooth landscape in a city in terms of patterns of Bluetooth presence and Bluetooth naming practices.

Configurational modelling of urban movement networks

Transportation research has usually seen road networks as inert systems to be navigated and eventually filled up by traffic. A new type of ‘configurational’ road network modelling, coupled to detailed studies of vehicular and pedestrian flows, has shown that road networks have a much more constructive role. They strongly influence the pattern of flows through quantifiable properties of the network ‘configuration’. Recent research results are presented showing that rates of vehicular movement in road segments are to a greater extent than previously realised the direct outcome of the location of those segments in the network configuration as a whole and that this is the case especially in the fine structure of the urban grid. A supply and demand model of urban movement is proposed in which the degree to which a street alignment is on simplest routes between all other pairs of alignments in the system determines the demand side of the equation, and the effective road width available to traffic determines the supply side. Regression analysis shows that these two factors alone account for the majority of the variance in flows from street to street (r2 ∼ 0.8). A model is then proposed of the evolution of the city in allocation of land uses to land parcels, and the allocation of capacity in the road network, where each reinforces the underlaying configurational logic through a feedback ‘multiplier’ effect. These findings suggest the possibility of using urban design parameters, such as the plan configuration of the street grid, building height, and street width, to arrive at a better controlled relationship between vehicles and pedestrians in urban areas. As these design parameters are under the direct control of the urban master-planner, the new techniques lend themselves to application in design decision support. A case example of the application of these techniques in the master-planning of the redevelopment of Londons South Bank cultural centre is presented.

The space of innovation: interaction and communication in the work environment

As the pace of organisational change accelerates and as new technologies demand more rapid responses from organisations to changing conditions in their business environment, buildings are being called on to play an active role in helping to generate new organisational structures and in facilitating individual communication. This raises questions not only of the nature of organisational structure and of how communication technologies will affect that, but also of the possible mechanisms by which spatial structure can affect patterns of interaction in the work organisation. In this paper we will review two recent research-led design projects in which space syntax techniques were used to help define the building brief for an organisation which depends for its market lead on its ability to innovate. Building on research into the design of research laboratories, we found that patterns of space use and movement generated by spatial configuration have a direct impact on the frequency of contact between workers in office-based organisations. The frequency of contact is shown in turn to have an impact on work-related communications cited as ‘useful’ by questionnaire. These patterns are found to be ‘system effects’ in that they cannot be attributed to an individual workers desk location but appear to result from the configuration of the whole system of spaces through which people move in their daily work, and have detectable effects on the mean ‘usefulness’ to others of all workers in a part of a building. The analysis suggests, however, that spatial integration alone may be insufficient to support flexible working and that spatial differentiation is necessary to provide the range of environments needed by different types of work activity.

An Algorithmic Definition of the Axial Map

The fewest-line axial map, often simply referred to as the ‘axial map’, is one of the primary tools of space syntax. Its natural language definition has allowed researchers to draw consistent maps that present a concise description of architectural space; it has been established that graph measures obtained from the map are useful for the analysis of pedestrian movement patterns and activities related to such movement: for example, the location of services or of crime. However, the definition has proved difficult to translate into formal language by mathematicians and algorithmic implementers alike. This has meant that space syntax has been criticised for a lack of rigour in the definition of one of its fundamental representations. Here we clarify the original definition of the fewest-line axial map and show that it can be implemented algorithmically. We show that the original definition leads to maps similar to those currently drawn by hand, and we demonstrate that the differences between the two may be accounted for in terms of the detail of the algorithm used. We propose that the analytical power of the axial map in empirical studies derives from the efficient representation of key properties of the spatial configuration that it captures.

Rejoinder to Carlo Ratti

In this rejoinder, we answer questions about space syntax raised in Carlo Rattis paper “Urban texture and space syntax: some inconsistencies”, and discuss theoretical assumptions underlying some of his criticisms.

Scaling and universality in the micro-structure of urban space

We present a broad, phenomenological picture of the distribution of the length of open space linear segments, l, derived from maps of 36 cities in 14 different countries. By scaling the Zipf plot of l, we obtain two master curves for a sample of cities, which are not a function of city size. We show that a third class of cities is not easily classifiable into these two universality classes. The cumulative distribution of l displays power-law tails with two distinct exponents, αB = 2 and αR = 3. We suggest a link between our data and the possibility of observing and modeling urban geometric structures using Levy processes.