Interior circulation. Introduction

This section deals with the movement of people in buildings and provides general guidance. Because it deals with people, many of the recommendations are based on empirical data acquired by observation and the experience gained in their application. Thus whilst the reader may apply the guidance given here, specialist assistance may be needed for complex or unusual situations.

The section is divided into five parts dealing with general factors, circulation elements, shopping centres, circulation in other buildings and the location of circulation elements.

General. The circulation of people in the interior of buildings is a complicated activity. It is affected by a number of factors:

- Mode (horizontal or vertical movement): People will generally be walking horizontally, except where they are using moving walkways; they will then change mode to reach a higher or lower level. To do this they will use stairs, escalators or lifts.

- Movement type (natural or mechanically assisted): People will move naturally when walking and be mechanically assisted when using escalators and lifts.

- Complicating factors (human behaviour): The movement of people around a building is complex because people are complex. Individuals have their own concepts of route, their own purpose for travel, their own level of urgency; their own characteristics of age, sex, culture, handicaps etc. There is an unpredictability in human behaviour.

The interior circulation in a building must be designed to:

- consider all circulation routes: these include principal and secondary circulation areas, escape routes, service routes and areas

- provide clear and obvious routes: pedestrians should be able to see the route to take, perhaps assisted by good signs and open vistas

- ensure that the circulation patterns are rational: an example is the avoidance of pedestrians passing through a lift lobby, where other persons are waiting

- ensure that incompatible types of circulation do not coincide: this would apply to pushing goods trolleys across a pedestrian mall in a shopping centre

- minimise the movement of people and goods: the location of related or associated activities is essential, e.g. sales and marketing, and personnel and training in an office building.

The design and location of portals (defined here as entrances, doorways, gates etc), corridors, stairs and mechanical handling equipment (i.e. moving walkways, moving ramps, escalators, lifts) must be coordinated to ensure:
- the free flow of people goods and vehicles
- that they occupy the minimum allocation of space
- that bottlenecks are prevented.

It is important to size each facility. Thus the handling capacities of corridors, which lead to stairs which in turn lead to a lift, should be adequately sized for their anticipated load. The term ‘handling capacity’ is used here for passive (non-mechanical) building elements in the same way that it is applied to the mechanical elements. The term ‘load’ is used to indicate the level of usage.

The efficiency of interior circulation depends on building shape. Both tall/slender and low/squat buildings are inefficient. The ideal shape is ‘compact’. Factors that influence circulation efficiency are:
(a) the relative location of rooms
(b) the relationship of major spaces with entrances and mechanical people handling equipment
(c) the importance of the journey undertaken (e.g. hospital theatre traffic)
(d) the separation of different traffic types (e.g. clean/dirty)
(e) the need to group some spaces together

(f) the conflict of vertical and horizontal circulation modes.

These and other factors lead to an imprecise knowledge of how circulation occurs in a building and permit only empirical methods of design. Much of what this section contains should be taken as general guidance only and cannot be proved theoretically. Many of the conclusions have been drawn from observations. Reasons are given for the conclusions so that if new evidence comes to hand (or opinions change) the results can be modified. Readers are referred to the references for fuller expositions and further reading. Regulations may also affect the circulation design, such as fire and safety codes, and these must be taken into account.

Note: throughout this section, people are often called ‘pedestrians’ when on foot and ‘passengers’ when being mechanically transported.