Responsive Environments PDF - A Manual for Designers

Ian Bently, Alan Alcock, Paul Murrain, Sue McGlynn, Graham Smith Responsive environments A manual for designers AMSTERDAM BOSTON HEIDELBERG LONDON NEW YORK...

Ian Bently, Alan Alcock, Paul Murrain, Sue McGlynn, Graham Smith Responsive environments A manual for designers AMSTERDAM BOSTON HEIDELBERG LONDON NEW YORK OXFORD PARIS SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYO ELSEVIER Architectural Press is an imprint of Elsevier Press Architectural Press An imprint of Elsevier Linacre House, Jordan Hill, Oxford OX2 8DP 30 Corporate Drive, Burlington, M A 01803 First published 1985 Reprinted 1987, 1992, 1993, 1994, 1997, 1998, 1999,2001,2003,2005 Copyright 0 1985, Elsevier Ltd. All rights reserved No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentall to some other use of this publication) without thc written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, WIT 4LP England. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the publishers. Permissions may be sought directly from Elsevier’s Science and Technology Rights Departmcnt in Oxford, UK: phone: (+44) (0) 1865 843830; fax: (+44)(0) I865 853333; e-mail: [email protected]. You may also complete your request on-line via the Elsevier homepage (http://www.elsevier.com), by selecting ‘Customer Support’ and then ‘Obtaining Permissions’. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloguing in Publication Data A catalogue record for this book is available from the Library of Congress ISBN 0 7506 0566 9 For information on all Architectural Press publications visit our website at www.architecturalpress.com Working together to grow libraries in developing countries www.elsevier.com I www.bookaid.org I www.sabre.org Printed and bound in Great Britain by MPG Books Ltd, Bodmin, Cornwall Responsive environrnents A manual for designers The authors Alan Alcock is an architect. He has worked in several Sue McGlynn is a town planner and an urban designer. London offices, including that of Powell and Moya, She has worked in a local planning team in the London before forming a practice which developed a special Borough of Hackney, and has researched into the design expertise in buildings for health care. and layout of housing estates, with the Social Sciences He is now a senior lecturer in the Department of Buildings Research Team at Oxford Polytechnic. Architecture at Oxford Polytechnic, where he played a She is currently a planning officer at Reading Borough central role in introducing the School’s uniquely Council, mainly working on listed buildings and pluralist Diploma course. His current interests include conservation areas. She has a special interest in urban researching the historical development of urban blocks, history, and is currently investigating the historical in their social and economic context. development of different types of residential layout.. - - -- Ian Bentley has practised both as an architect and as an urban designer, in Britain, Holland and the Middle East. He has also spent two years on the board of a property company engaged in both residential and commercial development. He is at present a senior lecturer at the Joint Centre for Urban Design at Oxford Polytechnic, - -. I and is a partner in the urban design firm of Bentley Paul Murrain is a landscape architect and urban Graham Smith trained as an artist, at St Martin’s and at Murrain Samuels. With Paul Murrain, Graham Smith designer. His experience includes both private practice the Royal College of Art, and taught at Goldsmith’s and others, he won awards in the RIBA inner city and work with the Milton Keynes Urban Design Group, College. He has paintings in public and private competitions of 1977 and 1980. of which he was a founder member. He is now a senior collections in Britain and France. His particular interests include designing develop- lecturer in the Joint Centre for Urban Design at Oxford He is currently a design tutor in the Department of ment strategies for the regeneration of run-down inner- Polytechnic, and a partner in Bentley Murrain Samuels. Architecture at Oxford Polytechnic, with a particular city areas, and researching the effects of the property His particular interests include the detailed physical concern for the relationship between architecture and development process on urban form, building imagery design of outdoor space, and of the interfaces between urban design. He has a specialist knowledge of two and and architectural theory. He has written on these and buildings and the public realm. A musician on three-d.mensional geometries; whilst his interest in the related topics, in both books and articles, and for keyboards and saxophone, he finds his understanding of architecture of the 1920s and 30s has been expressed television. musical structure to be valuable in design. through writing, photography and exhibition work. Contents Acknowledgements 8 Introduction 9 Chapter 1: Permeability 12 Chapter 2: Variety 27 Chapter 3: Legibility 42 Chapter 4: Robustness 56 Chapter 5: Visual appropriateness 76 Chapter 6: Richness 89 Chapter 7: Personalisation 99 Chapter 8: Putting it all together 106 Notes 143 Suggestions for further reading 144 Bibliography 147 Index 149  This book grew from our involvement in a series of From the world of estate agency, we are especially Acknowledgements projects, lectures and seminars under the general title Responsive Environments, running in both the Depart- grateful to Peter Gibson and David Massif of Gibson Eley and Co., and to Michael le Gray; whilst David Bell ment of Architecture and the Joint Centre for Urban of J.T. Developments, and John Foulerton of the North Design at Oxford Polytechnic since 1976. The approach British Industrial Association both gave invaluable developed in this forum has been tested in practice in advice and encouragement. various projects, and we owe a debt of gratitude to the Discussions with students have been central to the planners, architects, engineers, quantity surveyors, development of our ideas. Various students have developers and estate agents who have coped sym- undertaken studies specially to develop and test material pathetically with our sometimes unfamiliar ideas. In this for the book itself: we particularly wish to thank Glenn connection, Ian Bentley and Paul Murrain wish Almack, Robert Ayton, Douglas Brown, Francis particularly to thank their partners, Stef Campbell and Brown, Mike Cheesbrough, Alison Coaker, Basil Tony Hunt. The project which forms the basis of Constantatos, Brian Curtis, Kjell Dybedal, Nicky Chapter 8 was developed in collaboration with Fred Duckworth, Barrie Gannon, Marianne Grand, Ron Lloyd-Roche, Ken Baker and David Lock, of Conran Morgan, Ian Parry, Laura Rico, Nick Thompson, Andy Roche, architects and planning consultants. Trotter and Richard Welch. Several of our Oxford Polytechnic colleagues have The various drafts and the final manuscript have all been especially generous with time and advice: we are been typed by Vivienne Ebbs, Stella Thomas and Gillian particularly grateful to Richard Anderson, to Mike Long. They often had to work under pressure, and we Jenks of the Social Sciences Building Research Team, to are very grateful to them. Finally, we.must thank the Gordon Nelson of the Department of Architecture, to many publishers, copyright-holders and other owners of Brian Goodey, Richard Heyward and Ivor Samuels of illustrative material who have generously permitted the JoinKentre for Urban Design, and to Bob Bixby of their use here. the Department of Town Planning. Barrie Greenbie of the University of Massachusetts read drafts and made many useful comments. Ian Bentley Alan Alcock Paul Murrain Sue McGlynn Graham Smith 8  How does design affect choice? Introduction The design of a place affects the choices people can make, at many levels: - it affects where people can go, and where they cannot: the quality we shall call permeability. - it affects the range of uses available to people: the quality we shall call variety - it affects how easily people can understand what opportunities it offers: the quality we shall call legibility. - it affects the degree to which people can use a given place for different purposes: the quality we shall call robustness. - it affects whether the detailed appearance of the place makes people aware of the choices available: the quality we shall call visual appropriateness. - it affects people’s choice of sensory experiences: the This is a practical book about architecture and urban quality we shall call richness. design. It is meant to be useful on the drawing board, so - it affects the extent to which people can put their it does not tell you how to do things most designers know own stamp ‘on a place: we shall call this per- already: how to plan buildings efficiently for a given set sonalisation. of activities, how to keep the weather out, how to lay out This list is not exhaustive, but it covers the key issues in services and so forth. Designers sometimes do these making places responsive. Our purpose is to show how things rather badly, but at least ways of doing them well these qualities can be achieved in the design of buildings are known, and information about them is readily and outdoor places. available elsewhere. We are concerned with those areas of design which most frequently seem to go wrong. As a starting point, we are interested in why modern architecture and urban design are so often criticised as inhuman and repressive, despite the high social and political ideals shared by so many influential designers over the last hundred years. The tragedy of modern design, it seems to us, is that designers never made a concerted effort to work out the form implications of their social and political ideals. Once we understand this, it becomes obvious thz Indeed, the very strength of their commitment to these even from the political point of view it is the things ideals seems to have led designers to feel that a designers do to the built environment that matter. Ideals concentration on form itself was somehow superficial. are not enough: they have to be linked through Form, they felt, ought to be the by-product of appropriate design ideas to the fabric of the built progressive social and political attitudes’. But in environment itself. adopting this stance, paradoxically enough, designers This book is a practical attempt to show how this can failed to realise that the manmade environment is a be done. We start.from the same idea as that which has political system in its own right: try walking through a inspired most socially-conscious designers of the last wall, and you’ll notice that it is the physical fabric, as hundred years: the idea that the built environment well as the way it is managed, that sets constraints on should provide its users with an essentially democratic I what you can and can’t do. Multiplied to the scale of a setting, enriching their opportunities by maximising the I building or - crucially - a city, this is indeed a political degree of choice available to them. We call such places matter. responsive. 9  Permeability Variety Robustness Only places which are accessible to people can offer them Permeability is of little use by itself. Easily accessible Places which can be used for many different purposes choice. The quality of permeability - the number of places are irrelevant unless they offer a choice of offer their users more choice than places whose design alternative ways through an environment - is therefore experiences. Variety - particularly variety of uses - is limits them to a single fixed use. Environments which central to making responsive places. therefore a second key quality. offer this choice have a quality we call robustness. This is Permeability has fundamental layout implications. In The object of this second stage in design, which is the subject of Chapter 4. the diagram below, the upper layout offers a greater covered in Chapter 2, is to maximise the variety of uses in By this fourth stage in design, we have begun to focus on choice of routes than the lower one: it is therefore more the project. First we assess the levels of demand for individual buildings and outdoor places. Our objective is permeable. different types of uses on the site, and establish how wide to make their spatial and constructional organisation am a mix of uses it is economically and functionally feasible to have. Then the tentative building volumes already established as spatially desirable are tested to see whether they can feasibly house the desired mix of uses, and the design is further developed as necessary. - suitable for the widest possible range of likely activities and future uses, both in the short and the long term. 4 person office BaM i 3 perroi Cenfraal Beheer, Appeldoorn. Netherlands: Herman Hertzberger. Sitting space Rest spare Visual appropriateness Legibility The decisions we have already made determine the In practice, the degree of choice offered by a place general appearance of the scheme. Next we must focus depends partly on how legible it is: how easily people can on what it should look like in more detail. understand its layout. This is considered in the third This is important because it strongly affects the stage of design. interpretations people put on places: whether designers The tentative network of links and uses already want them to or not, people do interpret places as having established now takes on three-dimensional form, as the meanings. A place has visual appropriateness when these elements which give perceptual structure to the place are meanings help to make people aware of the choices Because it is so basic to achieving responsiveness, brought into the process of design. As part of this offered by the qualities we have already discussed. permeability must be considered early in design. The process, routes and their junctions are differentiated Designing for visual appropriateness forms the subject designer must decide how many routes there should be, from one another by designing them with differing of Chapter 5. First a vocabulary of visual cues must be how they should link together, where they should go and qualities of spatial enclosure. By this stage, therefore, the found, to communicate the levels of choice already - the other side of the coin - how to establish rough designer is involved in making tentative decisions about designed into the place. The appearance of the project is boundaries for blocks of developable land within the site the volumes of the buildings which enclose the public then developed in detail, using these cues as the basis for as a whole. This design stage is covered in Chapter 1. spaces. This process is discussed in Chapter 3. design. 10 Richness Putting it all together How to use the book The decisions about appearance already discussed still Taken together, Chapters 1 - 7 outline a step-by-step Each chapter has three parts: leave room for manoeuvre at the most detailed level of approach to achieving the qualities we have described: - an introductory section design. We must make the remaining decisions in ways 1. Permeability: designing the overall layout of routes - a set of design sheets which increase the choice of sense-experiences which and development blocks. - a series of footnotes users can enjoy. This further level of choice is called 2. Variety: locating uses on the site. Each part contains a different level of information. richness: it is the concern of Chapter 6. 3. Legibility: designing the massing of the buildings, By this stage, we are dealing with the smallest details of and the enclosure of public space. The introductory sections the project. We must decide whereabouts in the scheme 4. Robustness: designing the spatial and construct- Each introduction discusses how to design for the to provide richness, both visual and non-visual, and ional arrangement of individual buildings and particular quality concerned. Together, these sections select appropriate materials and constructional tech- outdoor places. give a comprehensive coverage of responsiveness as a niques for achieving it. 5. Visual appropriateness: designing the external whole. If you are not already familiar with the subject, image. the best way to start using the book is by reading Personalisation 6. Richness: developing the design for sensory choice. through all the introductions in sequence. The stages of design already covered have been directed 7. Personalisation: making the design encourage In our experience, it is necessary to consider all the at achieving the qualities which support the responsive- people to put their own mark on the places where qualities, even when designing quite small schemes. But ness of the environment itself, as distinct from the they live and work. the proportion of design effort expended on each quality political and economic processes by which it is In practice, things are more complex than this simple tends to vary; depending on the particular site, and on produced. This is not because we do not value the ‘public step-by-step structure implies: it is constantly necessary the scale of project concerned. Large, complex schemes participation’ approach: it is highly desirable. But even to modgy the emerging design as you think through the demand a greater proportion of time on the qualities with the highest level of public participation, most implications of each new step. This process is explored, covered in the earlier chapters, whilst smaller projects people will still have to live and work in places designed by means of a case-study, in Chapter 8: Putting it all are usually more concerned with the later ones. by others. It is therefore especially important that we together. Here we show the implications of designing to make it possible for users to personalise places: this is the support all the qualities together, in the context of a large The design sheets only way most people can put their own stamp on their i nner-ci ty redevelopment. Once designing begins, we need the second level of environment. information: a series of design sheets, covering the practical implications of achieving the qualities con- cerned. The sheets are arranged in the order we have found most useful in our own projects. The notes It is impossible for a book like this to cover all the eventualities which might arise when designing. So footnotes and suggestions for further reading open up a wider information network, for investigating particular topics in greater depth. And finally..... The book as a whole explores an approach to designing responsive places. It does not dictate a recipe. So it should be used creatively. All its ideas are intended as springboards for design, not as straight-jackets on the designer’s imagination. Designing for personalisation is discussed in Chapter 7. Here the designer is making the final detailed decisions about the forms and materials of the scheme; both to support personalisation, and to ensure that its results will not erode any public role the building may have. 11  Permeability and public space. The advantages of small blocks Chapter 1: The permeability of any system of public space depends A place with small blocks gives more choice of routes than one with large blocks. In the example below, the on the number of alternative routes it offers from one Permeability point to another. But these alternatives must be visible, otherwise only people who already know the area can large-block layout offers only three alternative routes, without backtracking, between A and B. The version take advantage of them. So visual permeability is also with small blocks has nine alternatives, with a slightly Introduction important. shorter length of public route. i Only places which are accessible to people can offer them choice. The extent to which an environment allows people a choice of access through it, from place to place, is therefore a key measure of its responsiveness. We have called this quality permeability. Permeability: public and private If everywhere were accessible to everybody, physically or visually, there would be no privacy. But one of our basic sources of choice stems from our ability to live both public and private roles.. For this capacity to Smaller blocks, therefore, give more physical permea- flourish, both public places and private ones are bility for a given investment in public space. They also necessary. increase visual permeability, improving people’s aware- ness of the choice available: the smaller the block, the easier it is to see from one junction to the next in all directions. The decline of public permeability Three current design trends work against permeable public space: - increasing scale of development. - use of hierarchical layouts. - pedestrianlvehicle segregation. Scale of development Unnecessarily monolithic developments, which could function equally well if divided into smaller elements, produce excessively large blocks. Of course, public and private places cannot work independently. They are complementary, and people need access across the interface between them. Indeed, this interplay between public and private gives people another major source of richness and choice. Public and private spaces, and the interfaces between them, each have different implications for permeability. Hierarchical layouts Segregation Permeability and the public/private interface Hierarchical layouts reduce permeability: in the example Permeability is effectively reduced by segregating the Since physical access to private space is necessarily below there is only one way from A to D, and you have to users of public space into different categories, such as limited, permeability across the public/private interface go along B and C: never A-D directly, or ADCABCD, vehicle users and pedestrians, and confining each to a is largely a visualconcern. This has different implications but always ABCD. Hierarchical layouts generate a separate system of routes. When this happens, the only for public and private space. world of culs-de-sac, dead ends and little choice of way to give both categories a level of permeability equivalent to a de-segregated system is through an The interface: visual permeability expensive duplication of routes. Visual permeability between public and private space can also enrich the public domain. If wrongly used, however, it can confuse the vital distinction between public and private altogether. This is because not all the activities in private space are equally private: there is a gradation, for example, from entrance hall to lavatory. To maintain the public/private distinction, the most private activities must be kept from visual contact with public space. The interface: physical permeability Physical permeability between public and private space occurs at entrances to buildings or gardens. This enriches public space by increasing the level of activity around its edges. We shall show how important this is in This is not to say that culs-de-sac are always negative: Chapter 4: for now, it implies that as many entrances as they support responsiveness if they offer a choice which possible should be located round the edges of public would otherwise be missing. But they must be added to a permeable layout, not substituted for it. \;' , ; \ 'Walkley Netherthorpe. Shefield, England 1 spaces, as opposed to what often happens nowadays. Avoid built-in segregation. Chapter 4 will show other ways of helping motorists and pedestrians to live together. And in any case, it is never necessary to build segregation irrevocably into a layout I I \ early in design. If we initially make a high level of permeability for everyone, then segregation can be achieved later, if necessary, by detailed design or management. This gives future users control over how they want to use the place, because they can de-segregate if circumstances change. 1962 1978 I Cardiff Wales 13  The need for fronts and backs The interface: effects on private spaces Summary: physical form and permeability This means that all buildings need two faces: afront onto For the public/private interface to make private life The implications of visual and physical permeability public space, for entrances and the most public activities, richer, instead of destroying privacy altogether, it is vital make powerful demands on design. The easiest way of and a back where the most private activities can go. This that its degree of permeability is under the control of the meeting these demands is by designing perimeter blocks: gives users the chance to do whatever they like in their private users. Do not worry about this: it is not difficult - fronts facing outwards onto public space - street, private space, including the right to make rubbish and to achieve at a later stage of design, by using normal square or park - close enough to enjoy its liveliness. clutter, without compromising the publicness of public building elements like level changes, windows, porches, - backs facing inwards to the centre of the block. space. curtains, sound-reducing glazing and venetian blinds. - private outdoor space at the back. This will be covered in Chapter 4. In our experience, other kinds of layouts nearly always W U lead to permeability problems of one sort or another. It may not always be possible to use perimeter block development, but its advantages are so important, and so difficult to achieve in any other way, that it should be considered as the obvious starting point for design. Starting the design We have explained the key factors governing permea- bility, and the reasons why it is a problem nowadays. because private activities out of doors are particularly The next step is to use these ideas in design. vulnerable to overlooking, they have to be screened by Links to surrounding areas. solid barriers. If they are at the front, adjoining public space, these barriers have a negative, deadening effect, In any project large enough to have more than one destroying the public character. Most of the private block, people can potentially move through the site from its surroundings, from one side to another. outdoor space must therefore be at the back. This choice will only be useful if people are aware of it, so Perimeter block development it is important to locate new routes as continuations Applied consistently, the front/back distinction - with from as many access points as possible outside the site private open space at the back, and public open space at itself, and make sure they can be seen to lead somewhere. the front - leads to a type of layout we call perimeter block development. This degree of control is often not provided nowadays: instead of leaving users to control how much permea- bility they want, designers decide for them, by making permanent physical and visual barriers. This is usually because the front/back distinction has been forgotten. The first step in design, therefore, is to analyse the layout of routes in the surrounding area; defining the access points onto the site, and noting their relative importance in terms of where they lead to. This is covered in Design 1 Headington, Oxford, England -7 Sheet 1.1. 14 Locating new routes. The block structure The tentative street positions now decided will start to Design implications This analysis can now be used to position the most important new routes through the site, as discussed in define blocks. These must now be checked for size: make How to achieve permeability Design Sheet I.2. them as small as possible. The minimum practicable size depends on the forms of their perimeter buildings, and 1. Analyse the streets and blocks of the sur- on the usage of the private outdoor spaces within the rounding area, to establish the relative im- blocks themselves. Both factors are discussed in Design portance of all access points to the site (Design Sheet 1.4. Sheet 1.1). 2. Locate new routes through the site (Design Sheet 1.2). Intensity of use 3. Analyse traffic roles of all the proposed new Now we have located all the routes through the site, it is streets, and check that street widths and junction useful to estimate how intensely each is likely to be used designs are acceptable to the traffic engineers by people from outside the site. We shall need this (Design Sheet 1.3). information when we come to consider the uses in the various blocks, in Chapter 2. For example, high levels of 4. Check that the blocks defined by the new streets traffic flow might inhibit housing unless handled are of practicable sizes (Design Sheet 1.4). carefully in detail. It is easiest to make these estimates while we still have the question of routes in the forefronts of our minds: ways of doing so are covered in Design Sheet 1.3. Junction design Next check that the junctions between the proposed streets are acceptable to the traffic engineers. This will I 1 depend on the traffic roles of the streets themselves, as Block shape discussed in Design Sheet 1.3. Overlooking at the corners can also be a crucial problem, if the blocks are densely built up. This has implications for both planning and massing which can be left till a little later. They are covered in Chapter 3. 15 1.1: Using existing links Connections to the main street system Next, find all the links within this area which connect the site to the Connections to immediate local surroundings Next, within the same area defined by the main streets, consider all the system of main streets. Compare them, to see which connect the site links to the site; including those which do not reach as far as the main most directly to the main streets. This can be assessed by comparing the streets themselves. Count the number ofconnections along each one in The starting point for a permeable scheme is the existing system of number of changes of viewing point necessary on journeys along each turn, as shown below. The highest numbers will show which streets links into and through the site from the surrounding area. Begin by link from the main street system to the site. In the sketch below, link A link the site most strongly to its immediate surroundings. analysing these links, and deciding how best to use them. requires only one change of viewing point and is therefore more direct Permeability is important at two scales: than link B, which requires three. - links which connect the site to the city as a whole - links which connect the site to its immediate local surroundings Connections to the city as a whole To achieve high permeability to and through the site from the city as a whole, we must connect it via the largest possible number of direct links to the system of main streets: those carrying through traffic linking the various parts of the city. So begin by finding the nearest main streets beyond the boundaries of your site, marking them on a detailed plan to a scale of not less than 1:10,000. 3 D tl ABC C0"ECTED EO JL FI I -2I K 53L 4 JL FOR EXAMPLE _.._ I re now know the relative ability of all the existine.links to connect the site both to the city as a whole and to t i e immediate local surroundings. This information can now be used to decide the relative importance of extending each link into and through the site, to achieve an appropriate balance between permeability at the city-wide and local scales. For instance, in Diagram 2, an east-west route would increase city-wide permeability, whilst in Diagram 3 a north-south street would have more effect on permeability at the local scale. Once you have decided which links it is most important to extend into and through the scheme, you can begin to align the system of streets and blocks within the site itself, as discussed in Design Sheet I.2. 1.2: Designing the street/block system 8 Give users a choice of routes through the site, by keeping perimeter blocks as small as possible. Check the block sizes you have created. Make them as small as practicable, depending on the uses they will house. If you already know these uses, check block sizes with Design Sheet 1.4. If you don’t, 80-90 metre blocks will do for most purposes (3). They should only need minor adjustment later, when uses are finally decided. Design sheet 1.1 revealed the most important links to the site. Starting with these, join the access points across the site ( l ) , taking account of any existing routes through it. Next, increase the sizes of any blocks which are too small, and subdivide any which are larger than they need If there are any existing buildings to be kept, note the positions of their fronts and backs. Make sire that be (4) to make the final layout as permeable as possible. Check with Design Sheet 1.3 to see that all the public routes run at their fronts. (2a,2b). junction designs are feasible. 17  Estimating vehicle flows 1.3: Street types and In the case of major roads linking into the main city network, it is necessary either to carry out a traffic survey, or to obtain the relevant To calculate the approximate flow from table 2, add together the figures for vehicles per hour for all the uses concerned (the exact figures used may vary slightly from one highway authority to another). Figure 3 illustrates a Dractical aDolication of this techniaue. junction design flow data from the local highway authority. On streets which carry only local traffic, approximate figures can be calculated from a knowledge of the uses in the buildings and land to which the streets give access. This Design Sheet shows how to estimate the approximate traffic 2 Building use Vehicles (vph) capacities and carriageway widths of the roads in the scheme, together Dwellings with 2 or more bedrooms 1 per dwelling with their junction designs, prior to detailed consultation with traffic engineers and highway authorities. Dwellings with one bedroom 0.75 per dwelling Street classification Both the spacing and the detailed design of junctions depends on the street types they connect. Urban streets are classified by traffic Elderly persons’ dwellings 0.25 per dwelling engineers according to their traffic role: the amount and type of vehicular traffic they carry (I). To classify the streets in your scheme, therefore, it is necessary to assess the vehicle flows which each will Schools: carry. 1 Urban street types pupils up to 12 years 1 per 4 pupils Design for free-flowing traffic is dominant concern. pupils aged 12 or more 1 per 6 pupils AU-purpose roads A Places for further education 1 per 2 pupil spaces Offices lper IOsq.m. (gross) or part Minor or existing warehouse or 1 per 5sq.m. (gross) or part Vehicles per hour I industrial unit Office block Local distributor Local distributor 1980sq.m. (gross) 198 Links traffic within local ‘environmental areas’. 0 Access roads Shopping 1 per I0sq.m. (gross) or part Public house 72 Access road - Major access Provides direct access to buildings and land within 0 - Collector 1 per space Commuter car parks ‘environmental areas’. - 0 U - Minor access Shared surfaces 15 No. shops 150 Short-stay car parks 2 per space 23 No. 3-bedroom houses 23 - Access ways - Mewscourts Churches 1 per 5 seats - Housing squares 32 No. I-bedroom flats 24 Residential roads Public houses 1 per 2.5sq.m. public area Total vph 467 Design for traffic subor- maximum traffic flow of 467 vph allows a 6.7m road width, wit1 dinate to environmental Clubs, halls and community centres 1 per 5sq.m. (gross) aiting permitted, and direct access allowed. (See table 4) factors and Pedestrians’ needs. (Source: Surrey C.C.) 18 Carriageway widths Junctions Note that you can only have blocks below 90 metres in streets which Once the streets have been classified, estimate the carriageway widths Next check the spacings between junctions from figurc 5. This shows only give access to housing: if you have not decided the scheme’s uses required; as shown in table 4. that 90 metre blocks between junctions will be large enough for most yet, you will have to re-check the junction spacings after working - situations: we suggest you use this dimension for the block layout even through Design Sheet 2.1. The classification of street types also affects the detailed design of junctions, as shown in figure 6. Use this -All-purpose roads for primary and district distributors. In these cases, traffic will not be permitted to use the intermediate intersections. But the layout will still information to sketch in maximum building lines at the corners of the Road type be permeable for pedestrians; and may eventually be opened up into a blocks. more permeable vehicle system, should traffic engineering rules or 6m 6.7m 7.3m street roles change in the future. I - l l Primary, District and Local dis- 1200 1350 1500 15 I l+s+ tributors, with no frontage access, no waiting, and negligible V V cross trafic. 6 District and Local Distributors 111-purpose roads Min. Spacing (metres) and Access Roads with high capacity junctions, but restricted A S waiting and access Primary distributor 275 * District distributor 200 * Local Distributors and Access Local distributor 90 * Roads with waiting and direct Access road 90 access allowed. * No standards exist for this categor) lote: crossroads are allowed in the following circumstances: - where important roads cross, these generally have to bc controlled by traffic signals, roundabouts or grade separation hb Residential roads Road type Maximum flow (vph) width (m) 4. I - where there are clear priorities, and the minor ‘cross’ roads an controlled by ‘give way’ or ‘stop’ signs. :or junctions with very minor roads, staggered junctions are advised rith spacing S at a minimum of 40 metres. at 50mph Local Distributor 400 (min) 6.7 120 Residential roads Min. spacing (metres) at 40 mph A S Local distributor 90 40 District distributor Local distributor 9 90 10.5 Major access road 300 5.5 Local distributor Access road 9 90 10.5 Major access road 80 40 Access road Access road 4.5 60 6 Collector road 150 5.5 Collector road 50 25 Residential roads Access road 45 5.5 Road A Road B Access road 30 15 )istrict or local Local distributor Access way 20 4.5 listributor Access way 25 10 Local distributor Major access road 4.5 75 10 Mews Court 15 4.8 Wajor access road Collector road 4.5 60 9.14 Housing square 15 4.8 Mews court 30 20 Zollector road Access road 3 60 6 kcess road Access way 2.4 40 6 Housing square 30 15 4ccess way Access way Mews court 2.4 30 4.5 In practice, in consultation with traffic engineers, it may be possible to Housing square reduce dimension S to zero, at junctions between minor residential roads.  1.4: Checking block Perimeter blocks with non-residential buildings Worked examples Example 2 (see PP. 21-23) At a given building height, what is the minimum block size to achieve a given parking standard? The graphs are based on continuous perimeter buildings. No sizes allowance is made for space between fronts of buildings and backs of pavements, nor between backs of buildings and parking areas. If you - Start by locating the desired parking standard ( I ) - draw a line upwards from it to intersect the relevant building height line at (2) want to include either of these, the average block dimension must be - draw a line across from (2) to read off the minimum practicable increased as shown below. The purpose of this Design Sheet is to provide a quick way of checking block dimension (3). which uses could be accommodated within the tentative street/block structure already developed. This is an essential preliminary to investigating the demand for different uses, to be covered in Chapter 2. I I The minimum size of a perimeter block depends on two main factors: - the private activities to be housed in the outdoor space within the block: usually private gardens, service access and parking or garaging. - the form of the buildings around the block perimeter. Because these factors vary with different building uses, this Design Sheet is divided into three sections, covering the following uses: - non-residential uses - flats - houses with gardens Each section contains a series of handy reference graphs displaying the relationship between three factors: - the overall size of the block Parking standard: - private outdoor space and parking or garaging provision within Cars per gross sq.m. built space the block Example 1 (see pp. 21-23) - characteristics of the buildings around it Given block size and required parking standard, which building height The graphs are based on rectangular blocks of the form sketched will enable the maximum area of building to be accommodated in the below. The ‘average block dimension’ referred to is the mean of two block? Example 3 (see pp. 21-23) adjacent sides: (A + B) - 2 in the sketch. - Start by locating the relevant block size (1) Given block size and building height, what parking standard can be - draw a line from it across the graph (2) achieved? - locate the relevant parking standard (3) - Start by locating the relevant block size ( I ) - draw a line upwards from it (4) - draw a line across to intersect the relevant building height line at - the nearest graph line below the intersection of (2) and (4) (2) indicates which building height will achieve the maximum - draw a line down from (2) to find the parking standard which can floorspace. be achieved (3) In practice, the dimensions A and B will usually have to be adjusted by Parking standard: Parking standard: a few metres to achieve an efficient parking or garaging layout. At this Cars per gross sqm. built space Cars per gross sqm. built space early stage in design, however, the graphs give an adequate method of checking which uses could be housed in the blocks you are proposing. 20  Parking standard cars per gross square metre built space Block sizes: non-residential buildings 21  Perimeter blocks with flats Worked examples Example 5 (See p23) The graphs make no allowance for gardens or parking spaces at the Given the area of the desired flat type, what is the minimum block size front, or for private outdoor spaces within the block. If you want to to achieve a given parking standard? include these, the average block dimension must be increased as shown - Start by locating the desired parking standard ( I ) below: - draw a line upwards from it to intersect the relevant flat area line at (2) - draw a line across from (2) to read off the minimum practicable block dimension (3)..-. 'I I I I I I I I I I I I Example 4 (See p23) I I Given block size, garden area and required parking standard, which I flat size will enable the maximum number of dwellings to be I accommodated in the block? I - Start by locating the relevant block size (1) Example 6 (See p23) - draw a line from it across the graph (2) Given block size and desired average flat area, what parking standard - locate the relevant parking standard (3) can be achieved? - draw a line upwards from it (4) - Start by locating the relevant block size ( I ) Average block dimension is - the nearest graph line below the intersection of (2) and (4) - draw a line across to intersect the relevant flat area line at (2) (A+B) - 2 indicates which flat size to use to achieve the maximum number - draw a line down from (2) to find the parking standard which can of dwellings. be achieved (3). In m E c E c H B C E.-In.-U7 E a B a ii aa aa M 0 M 0 E E ? d 2 22  0 20 40 b 80 loo 120 la0 160 IS0 0 2C 40 60 SO 100 !20 Iq.0 I60 /go Parking standard: %'dwellings Parkine standard: Y dwellings Parking standard: Y dwellings Block size: flats  Perimeter blocks with family houses Worked examples Example 8 (See pp. 25-26) The graphs are based on terraces of 2-storey houses, and make no Given house type and garden size, what is the minimum block size to allowance for front gardens or front parking spaces. If you want to achieve a given parking standard? include these, the average block dimension must be increased as shown - Start by locating the desired parking standard (1) below. - draw a line upwards from it to intersect the relevant house type / garden size line at (2) Allow for this space in the - draw a line across from (2) to read off the minimum practicable average block dimension _____ ____- 1 ____ block dimension (3)... m 2 c B a.- a f ,____ --- I a5 I M B I I E I I I t I I 1 1 I I z I I I ng standard: I Example 7 (See pp. 25-26) I i II Given block size, garden area and required parking standard, which dwellings i house type will enable the maximum number of houses to be I I accommodated in the block? Example 9 (See pp. 25-26) I I I - Start by locating the relevant block size ( I ) Given block size, house type and garden area, what parking standard I - draw a line from it across the graph (2) I L- ~ - locate the relevant parking standard (3) can be achieved? - Start by locating the relevant block size ( I ) - draw a line upwards from it (4) - draw a line across to intersect the relevant house type / garden U - the nearest graph line below the intersection of (2) and (4) Average block dimension is size line at (2) (AfB) i 2 indicates which house type to use to achieve the maximum - draw a line down from (2) to find the parking standard which can number of dwellings. be achieved (3) m e * B E.- E.- ‘d a B %I 2 z 24  7. 0 40 60 80 100 120 IW 160 isu Parking standard: % dwellings Parking standard: % dwellings I Block sizes: family houses with 50 sq.m. gardens. 25  ~ 9 I Block sizes: I 0 /1 0 20 40 60 80 100 I20 1'4-0 160 180 0 20 40 60 80 100 120 IF0 160 190 0 20 40 Q 80 I00 1-20 144 160 180 Parking standard: % dwellings Parking standard: % dwellings Parking standard: % dwellings Block sizes: family houses with 100 sq.m. gardens. 26  Variety and choice Why is this a problem? Chapter 2: Variety The purpose of promoting variety is to increase choice. Though their attitudes differ, both developers and But choice also depends on mobility: people who are planners want eficient environments. Developers are