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The planning of single-storey layouts
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Build. Sci. Vol. 1, pp. 127-139. Pergamon Press 1965. Printed in Great Britain.
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721
The Planning of Single-Storey Layouts B. WHITEHEAD* and M. Z. ELDARS*
action. Initial capital costs tend to loom large in the minds of the client and architect, but the costs which continue month by month, t h e ' costs in use ', tend to be hidden by their piecemeal nature and by the lack of a readily visible alternative as a standard of comparison. These and perhaps other reasons lie behind the apparent tendency of the architect to undervalue, in relation to other facets of the design, the effect on total costs over the life of the building of the organisation of activities within the building and their associated human movement costs. Obviously the design of any building must be a compromise between many factors and restrictions. Financial resources and the size or shape of the building site set initial limits; within these limits it is necessary to provide an environment suitable for human beings to work in and it is also accepted that human movement within the building should be as efficient as is compatible with the other design restrictions. Lack of data on this latter aspect and, as pointed out above, lack of information on its relative importance, often, however, lead to lipservice being paid to it. An indication of the financial relationship between initial and running costs is given by Stone [2] who states that ' At current rates, service staff cost about £500 a year; this is equivalent to an initial cost of £10,000. It is, therefore, worth spending up to this amount to eliminate the need for a liftman, stoker or cleaner '. Stone [3] also states, for factory buildings, that ' labour and material costs are likely to be so large compared with building costs, that comparatively small proportionate savings in these fields are likely to more than repay for the costs of rebuilding '. The relative importance of initial and running costs is obviously not the same in all types of building, but a pointer may be taken from studies in a hospital operating theatre suite [4, 5] where the cost breakdown was found to be : I
INTRODUCTION IN manufacturing industry the detailed planning of the layout of production floors and their ancillary services has long been recognised as being of vital importance to the ultimate efficiency of the working unit. Techniques were provided by the early 'industrial engineers ', which could be used as a basis for solving industrial layout problems and Muther [ 1] has recently attempted to systematise the use of such techniques in layout planning to ensure that all the various factors, objectives and physical limitations are given due weight. The most essential feature of any study designed to improve upon an existing situation is, of course, the use of data from that situation in the analysis and synethesis leading to the proposed solution. Where there is no existing situation, e.g. where a department to manufacture an entirely new product is to be set up, data from the product design and work study departments giving the necessary sequence of operations, together with information from the sales department setting out the estimated quantities required, will be used as the best available substitute. In building, on the other hand, possibly because of the division between the architect and the builder, there has been a tendency to make relatively little use of feedback information, Emphasis has tended to be placed on the development of original designs and in many cases attempts have been made to fit the functional square peg into the aesthetic round hole. Buildings, once erected, have been regarded as completed jobs rather than as the base-line from which to proceed in the design of other buildings of similar type and, consequently, there has been little attempt to obtain information on how well, or badly, particular features of a design have operated. Failures in some facets of a building are, however, much more dramatic than failures in others and draw, perhaps undue, attention to themselves. If the structure gives way or the roof leaks, remedial action has to be taken, but, if the arrangement of spaces in the building is such that the cost in salaries and wages of using the building is, say, 25 per cent above what it need be with an alternative arrangement, there is no urgent pointer to the necessity for
Table 1. Approximate percentages of total annual cost.
Buildings and equipment (amortized at 5~ of initial cost per annum) Maintenance, cleaning, heating, lighting and materials Staff, salaries and wages
7 22 71
The cost of human movement between rooms was found to be approximately one third of the total
*Department of Building Science, The University, Liverpool 3. 127
128
B. Whitehead and M. Z. Eldars
salary cost of staff time, that is, about 23 per cent of the total annual cost of the suite, thus showing the large potential for savings in that sphere and, in default of other equally measurable and important criteria, presenting a strong case for the use of the circulation of people as the prime data in deciding the layout of that type of building. Some industrial production areas, where the large scale manufacture of one type of product or the great weight of material to be moved enforce a very definite path of movement upon the process, may be regarded as exceptions in that human movement will in these cases be a subordinate factor. Most other types of building, on the other hand, e.g. office blocks, warehouses, houses and schools are likely to be found to approximate more closely to the pattern shown by the operating theatre suite mentioned above. For the purpose of this paper, then, although it is realised that in individual cases some factors must modify the layout or even be of paramount importance, human movement is regarded as being the prime data in layout problems. The effect of this assumption is to simplify the problem considerably since the movement of people in buildings similar to the one to be designed can be objectively observed, recorded in numerical form and analysed. In planning a layout the architect normally starts by making a layout diagram. The diagram consists of different activities or cells connected to each other by proposed circulation routes, sometimes differentiated according to degree of importance. The design then proceeds by trial and error until a compromise is reached which more or less satisfies all the known factors and restrictions. It would be possible in many cases for the architect to carry out an investigation in a building of similar type to the one he is designing in order to obtain numerical data on which to base the locating of activities in relation to one another, but the fee structure of his profession does not encourage so detailed an approach and the means of analysis of such data have not been available. The position has changed somewhat in the recent past in that, for instance, the Building Research Station [6] has started to collect data on the movement inter-relationships between the various parts of a hospital. An extension of this approach could lead to ' potted data ' on the relationships between different types of activity in specific situations becoming available for amendment and application to particular problems. Several attempts have also been made to provide a means of analysis of such data and the remainder of this paper will largely be concerned with a summary of some of these approaches and a more detailed description of one.
BACKGROUND The traditional techniques for layout planning are, as described by Shaw [7] and others, the flow and string diagram, the process chart, sometimes
combined with a flow diagram, the use of templates for trial layouts within a storey and of models for more sophisticated single and multi-storey work. Recent work on the use of models has been done by' the Building Research Station [8, 9 I. it was always realised that the final result must, of necessity, be a compromise between many factors, but the work of Muther (above) has probably been of considerable assistance in ensuring a logical pattern of work and allocation of priorities. Moseley [10, I I ] attempts to find a rational basis for deciding the shape of multi-storey buildings and for allocating accommodation to optimum positions in such buildings. He concerns himself largely with interfloor movement rather than with movement on one floor and adopts a simplifying assumption to facilitate the use of linear programming in finding the optimum location of each unit of accommodation. This is basically that ' all journeys are made from a hypothetical " mean point of origin '~ to the location under consideration ', in effect through the " vertical circulation point '; the object of this assumption is to circumvent the difficulty caused by the fact that a move of one unit of accommodation from one position to another affects the ' cost ' inter-relationships of all the other units and, in the absence of this assumption, prevents a single access distance (or circulation cost) being set for each possible location. Archer is reported [121 to have 'conceived the idea of turning the transportation technique inside out and using it to optimise the locations of the points of origin instead of the movements between them '. In a similar way to Moseley, he assigned a value to the importance of the connection between each pair of activities, then set up a topological model based on the expected shape of the building and assigned distance factors between the various possible locations in the grid. A transportation type linear programming technique was then used to produce the allocation of activities to locations which would give the minimum communication cost between one of the activities and all the others. As pointed out in correspondence [13] the answer could only be a partial one since it did not consider the inter-relationships between the activities and, whilst it might be the optimum from the point of view of the given activity, it might be a very bad answer for the building as a whole. If, for instance, in a hospital the operating theatre was regarded as the activity around which the planning of the hospital was to be optimised, it might well be foundthatin t h e ' optimum ' answer, the out-patient department was at one end of the hospital and the X-ray department at the other, despite the fact that these two had a very close relationship one to the other. Further trials using other activities as the central point might well give irreconcilable answers. It would, in fact, seem that, as Moseley found, a move of one activity from one location to another changes the ' c o s t ' inter-relationships of all the other activities and therefore prevents the assigning of a single cost to each location (a necessary condition for linear programming).
The Planning of Single-Storey Layouts
129
importance should not cut across the line(s) already on the ' g r a p h ' . The shape may be altered to accommodate each addition, but any line which cannot be added without cutting across other lines is omitted. Lines in the final network represent direct room-to-room connections. Areas of rooms
Moseley did not use a computer but realised the obvious applicability of such a tool to his approach. Archer regarded a computer as an integral part of his technique. The approach by Whitehead and Eldars[4, 5] described later in this paper, also could not be economically carried out without the use of a
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Fig. 1. String diagram of movements of state enrolled nurse during one day's duty in existing operating theatre suite.
computer. Leven[14], on the other hand, recently put forward a technique based on ' graph theory ' which is intended to require pencil and paper only. The basic idea is that, if two points representing the two activities with the strongest connection in a building are joined by a line, then other relationships subsequently added to the diagram in order of
and other considerations are taken into account in transforming the network into a spatial layout. In correspondence[15, 16] it was pointed out and agreed that although the approach was simple, it would not be feasible to use it to decide the layout of large numbers of activities because of the complexity of the ' graph ' and the time consumed. The
130
B. Whitehead and M. Z. Eldars
technique uses only a ranking of the order of importance of connections as data and it is evident that, once a link has been drawn into the ' graph ', that link is (until the spatial layout stage) regarded as being equally as important as those previously
Buffa, Armour and Vollmann[17] working in U.S.A. report the use of a computer programme which starts with an arbitrary or existing layout grid and exchanges pairs of activities or elements until the exchange which saves the most in terms of
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drawn, despite the fact that their importance may really differ by a factor of ten or more. Also it cannot, using ranked data, take the total importance of the connections between one activity and all others into account.
distance or cost has been found. A permanent change is then made in the proposed layout and a further set of pairs of exchanges is evaluated. The process is continued until further exchanges yield no extra savings. The programme is said to be
131
The Planning of Single-Storey Layouts economical in computer time and to yield considerable savings. Souder and others[18, 19] also working in U.S.A. suggest the possibility of on-line architect-computer communication using an oscilloscope to display data on the workings of existing buildings. Modifications to simulate the anticipated activities in a proposed building would be made by drawing on the oscilloscope face with a light pen and the ' costs' of the proposals would be computed and displayed. It is obvious that such a system would marry the intellectual capacity of the man to the storage and calculating capacity of the computer, but might well be very expensive in computer time. A COMPUTER-AIDED A P P R O A C H It was obvious when work commenced on this approach that current work using linear programming could, as argued above, only optimise for the location of all the activities in a building in relation to one point. It was, therefore, considered necessary to evolve a method which would take into account as many of the inter-relationships between activities as possible. A considerable number of string-diagram studies had already been done to determine the pattern and volume of movement in a typical hospital operating theatre suite and empirical attempts had been made by traditional techniques to evolve a layout which would both rninimise the necessity for movement in a re-arranged suite provided with similar accommodation and incorporate new facilities suggested on movement-economy and medical grounds (figures 1 and 2). For most categories of staff in the suite it was found to be possible to achieve considerable reductions in the movement necessary but it was impossible to say how closely the layout derived approached the optimum because of the innumerable variations which it is possible to make in laying out a number of units of accommodation and the consequent work in calculating the total cost of each arrangement. The data collected in the string diagram studies were used as the basic material around which to build the computer approach, but, to apply the technique to a different type of accommodation, it would be necessary either to take observations in a building of similar type to the one to be designed or to make use of the best available estimates. The final result can, of course, reflect no more accuracy than is contained in the original data and the rougher the data, the less worthwhile it becomes to use refined analysis techiques. In order to avoid bias in the data, observations should be made over a representative period (i.e. a period of time covering at least one complete cycle of the activity concerned) and for each type of staff employed.
General preparation of data Assuming that data have been collected, the following steps are suggested as being necessary to prepare them for any form of computation :--
1. The data are plotted as string diagrams for each individual type of staff. 2. The heaviest concentrations of movement shown on the string diagrams are critically examined with the aid of notes taken during the observations to determine whether the reasons for the movements can be removed by changes in organisation or by changing the types of accommodation provided. 3. The data are modified to take any desirable changes in organisation or accommodation into account. 4. The number of journeys between each pair of points at which work is done is counted for each type of staff. (The terminal points of journeys may, on different scales, be points within one room, whole rooms or even whole buildings if the technique is used to optimise the layout of a complex of buildings. For convenience these terminal points will hereafter be referred to as ' activities '.) 5. The number of journeys between each pair of activities for each type of staff is multiplied by the normal number of that type of staff employed. 6. The number of journeys for each type of staff is modified by a factor representing the relative cost (salary plus overheads) of that type of staff in relation to the average. For example :--
Table 2. Total annual cost (salary and overheads) £ (assumed figures)
Factor
2400
1-6
1475 750
1.0 0.5
Surgeon Average of aU theatre staff Student nurse
If, then, a surgeon and a student nurse both made one hundred actual journeys between two activities the result, weighted according to cost, would be :--
Table 3. Standard Journeys
Surgeon Student nurse
100 x 1-6 100 x 0-5
160 50
7. The total number of modified ( o r ' standard ') journeys between each pair of activities is obtained by adding together the totals for each type of staff. 8. At this point factors other than movement can be introduced into the calculation if, in the particular situation, it can be agreed what their values relative to that of movement are. If, for instance, in case of fire, it is essential to get from point A to B in the minimum time, then the number of standard journeys between A and B can be modified to take this into account.
132
B. ~'/litehead am/M. Z. Eldars
9. The totals can now usefully be set out in an association chart (figure 3) showing the interrelationships between all activities in numerical form.
Further preparation of data for programme described Up to this stage the preparation or standardisation of the data has been such as would be required for almost any form of computation. The follow-
It is suggested that this order of importance be determined as follows:-(a) The total number of standard journeys between each activity and all others is calculated from and written into the association chart (figure 3). The activity which has the largest number of contacts with all other activities is chosen as the starting point for the building of a new layout, e.g. activity 13 in figure 3.
Fig. 3. Association chart.
ing steps are more particularly related to the ' Algol ' programme written and tested by Eldars :-1. Because of the nature of the problem, namely that a move of one activity from one location in the layout to another affects the inter-relationships of all the activities, it is essential to solve the problem step by step. It is therefore necessary to make the most important decisions first, in this case to locate the activities in a plan layout (or 'locations matrix ') in order of their importance from the point of view of the factors evaluated by the figures o f ' standard journeys '.
(b) The second activity to be positioned in the new layout is taken to be the one which has the largest number of contacts with the first selected activity, e.g. activity 12 in figure 3. (c) The third activity to be positioned is the one which has the largest number of contacts with the first and second activities combined, e.g. activities 9 or 14 in figure 3 (the two theatres are identical). (d) The order in which all the remaining activities will be dealt with by the computer is determined in a similar way, taking into account the relationship of each activity to all the previously selected activities.
The Planning of Single-Storey Layouts
(i.e. a number much higher than any of the calculated relationships) as the inter-relationship between elements in the same activity; this ensures that the computer will locate the elements next to one another and so avoid the splitting in the computer plan of units of accommodation which are in practice indivisible. It should be noted that the process of apportioning the number of standard journeys to individual elements is subsequent to the determining of the order in which the activities (and hence the elements) will be located by the computer in a plan layout. The order is not then affected by the differ-
2. To arrive at a reasonably realistic answer it is necessary to take the areas required for the various activities or units of accommodation into account. It is assumed that the area required for each is determined by means outside the scope of this paper and that each area includes an allowance for circulation. Moseley[10, 11] suggested 10ft x 10ft as a convenient unit floor area (i.e. the area of a small room) and this is used in the following example. It is then necessary to (a) find the number of units of floor area (or ' elements ') required for each activity.
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(b) determine the number of standard journeys between each pair of elements from different activities; this may be calculated as (Total number of standard journeys between two activities)
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ing relationships which the inclusion of the number of units of floor area in the calculations throws up. 3. Any activities which are to be pre-located ~hould be specified. 4. The final data showing the number of standard journeys between each pair of elements can be set out in a 'relationship matrix' (or expanded association chart) (figure 4) and punched into paper tape. The paper tape is then ready for feeding to the computer with a programme of instructions.
Automation of data preparation It is probable that future work will extend the computer programme described below to cover a considerable amount of the manual working-up of
134
B. Whitehead and M . Z . Eldars
data set out above. The relatively raw data to be fed into the computer would then be : - 1. Salary and overhead costs of each type of staff. 2. Number of actual journeys between each pair of activities made by each type of staff. 3. Number of each type of staff employed. 4. Number of units of floor area required for each activity. 5. Any restrictions or over-riding factors. The present computer programme 1. A n illustrated d e s c r i p t i o n - The principles of
the process through which the computer goes in locating a set of activities in relation to one another can be illustrated by an example representing a rearrangement of accommodation in an existing operating theatre suite. To avoid misunderstanding, it should perhaps be stated that this set of accommodation does not necessarily contain all the facilities which might today be regarded as being desirable in an up-to-date suite. This has been done
M
Fig. 5. Locations matrix with one activity prelocated.
to maintain as strict a comparison with the existing suite as possible. The suite contains 21 rooms (which can in this case be equated w i t h ' activities ') * The cost of each temporary location is determined by:-(a) calculating the distance (assumed to be in a straight line) from the centre of the location to the centre of each occupied location. (b) multiplying each distance by the appropriate number of standard journeys between the particular elements. (c) adding the answers. The assumption that the distance between the centres of two locations can be measured by a straight line is, of course, a simplification. The actual walking distance would be affected by the positions of doorways and the convenience of circulation routes, but it is self-evident that, if the straight line and actual circulation costs for a certain layout are compared, then the closer the actual approaches the straight line cost, the more efficient are the circulation routes employed. The ratio (actual circulation cost)/(straight line circulation cost) was calculated by Eldars for several layouts. Those layouts which had been empirically designed produced ratios approximating to 1-20; those which had been derived from the computer output gave ratios of about 1-05. It would, therefore, seem that, for efficient layouts, the straight line distance is a sufficiently close approximation to justify its use in calculations.
Second activity (elements 5 and 6) ~'-~ First activity (elements 1,2,3 and 4) f Third activity (elements 7,8,9,10,1t and 12
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Fig. 6. Locations matrix with 3 activ#ies located.
and the total area can, as partially illustrated in figure 4, be broken down into 55 units of area or elements. Suppose then, that a locations matrix (figure 5) with, say, 39 squares per side is set up in the computer's information store, each square being recognised by its store number, that each of the 1521 squares can be used as a possible location for one element, that the matrix is likely to be adequate in size to contain the final plan layout and that the activity which is first in order of importance is to be pre-located in the centre of the locations matrix to form a reference point around which to build the rest of the layout (figure 5). There is no problem in positioning the second activity when only one activity has been pre-located since it must be next to and can be on any side of the pre-located activity. The positioning of the third activity in the optimum location requires some calculation and the complexity of the decision as to where to locate each subsequent activity increases as the pattern builds up. I f it is assumed, to give the problem reality, that the elements comprising three activities have been located, the next step will be to supply to the computer the element number of the first element of the fourth activity (element no. 13) and the numbers of standard journeys between this element and previously located elements. The programme is so arranged that the computer will then temporarily position element no. 13 in a location adjacent to the locations already allocated to other elements in the first three activities and will calculate the total ' c o s t ' of this temporary location.* The cost will be stored in the ' memory ' of the computer and the element will then be moved in turn to all other possible locations on the immediate perimeter of the locations already occupied (figure 7) for a similar calculation to be made. When all the locations have been costed, the computer will compare the stored costs, select the least costly location and permanently position the element in that location. The second and subsequent elements of the fourth activity will be dealt with in a similar way, but, because of the high dummy relationship between the elements of the one activity, they will,
135
The Planning of Single-Storey Layouts
[[I m
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Fig. 7. Locations matrix showing all possible locations of element 13. PROGRAM REF NO ELEMENT NO
LOCATION 11 21 31 41 51 61
71
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NO 7611 7601 722t 7211 7621 723J
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LAYOUT oPTIMISATION
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the computer as a series of storage positions and the form of the matrix has to be interpreted from the computer output (figure 8). The left hand column of figures in the output gives the element numbers and the right hand column gives their respective locations. The interpreted matrix form is shown in figure 9. The groups of elements forming whole activities can now, by reference to the relationship matrix (figure 4), be outlined to show the positions of whole activities (figure 10). The final step in the process, the conversion of the diagrammatic, theoretical layout into a practicable form is, and may well remain, an empirical process because of the difficulty of building every conceivable, material factor into a general computer programme. The necessity in some rooms for daylighting by windows in outer walls could possibly be built into a future programme but the particular requirements of specific situations, such as the need to maintain aseptic conditions in an operating theatre suite, would be entirely irrelevant to other buildings and, unless they could be expressed as restrictions in the data, would be best considered in an empirical stage. An assumption was made above that an allowance for circulation was included in the area allocated to each activity; it is at this stage that the allowance is separated in the form of corridors and other circulation spaces. Some amendments to the location of activities may be necessary to cover the specific requirements mentioned above but such amendments should be regarded as deviations from the near optimum computer solution and should, therefore, be restricted to the essential minimum.
Fig. 8. Computer output. (part of).
as a prior requirement, be positioned next to the first element and to one another, the exact location and shape of the room housing the whole activity depending on the strength of its relationship to other located activities. The elements comprising the other activities required in the layout will be positioned in the same way around the growing nucleus, the final location of each element depending on its relationship to each of the previously located elements. The completed locations matrix will only exist in
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Fig. 10. Diagrammatic layout derived from computer.
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ft F&'. 12. A possible second in the conversion (ff the diagramatic layout to a practicable jbrm.
The Planning of Single-Storey Layouts Figures 11 and 12 represent two possible stages in the conversion of the diagrammatic layout to a practicable form. Assuming that the staff in the suite shown in figure 11 would follow the same traffic pattern, the actual circulation cost for that suite would be 28 per cent less than for the existing suite. Although figure 11 is fairly close to the theoretical layout shown in figure 10 it is possible that objections to the layout would be raised because of the ' less clean ' corridor separating the scrub-up, sterilising and sink rooms from three of the theatres. It is also possible that the weighting given in the data to a porter pushing a patient on a trolley ought to have been greater, in which case the computer answer might have been closer to that shown in figure 12. The actual circulation cost for figure 12 would, on the same assumption as for figure 11, be 23 per cent less than for the existing suite, a monetary saving of about £3000 per annum. Checks made by asking experienced hospital architects to produce minimum circulation cost plans for the same accommodation by empirical methods gave cost results no better than that for the existing suite, thus verifying the usefulness of the computer approach.
2. The Algol programme--The Algol programme (figure 13), when supplied to the computer with data (figure 14), will carry out the procedure illustrated in the previous section. The annotations to the figures describe the function and operation of the various parts of the programme and data. The time taken on the KDF9 computer, using the l~in .....
intc~er n,m,p,w,a,b,l,e,j,S,eln,eld,Lm,LN,LNT;real C,D,MIN; -'-n'~AD~TA; p :-DATA; m I-DATA • TEXT(ILAYOUT*OPTIMISATION~ ;NEWLINE(2) ; T~T[[EI~MENT-NO~);SPACE(~)~TEXT(~I~3CATID~"NG );NEWLINE I); be~in--lnte~er array L I :n~eJ,Loc[T:mx~ ,EL[I I~l IA 1:2 ; real a r r ~ cost[l : ~ ] , J [ 1 :m-l];
137
Kidsgrove translator, to locate certain numbers of elements is shown in table 4. Table 4.
No. of elements
21 32 41 55
Actual computing time
Overall time taken on computer
Min
Sec
Min
Sec
0 0 0 1
12 23 50 32
0 1 1 2
53 6 32 15
It is obvious that, although the time taken will increase more than in proportion to the number of elements added to the problem, the limit at which the extra time per element added would be uneconomically long has not been approached in the figures quoted. CONCLUSION The variety of approaches to layout planning problems indicates, firstly, that a substantial body of opinion exists which is not satisfied with the efficacy of traditional methods used by architects and others and, secondly, that new techniques are in a relatively early stage of development. It is certain that refinements to proposed methods are necessary and very likely that they will be superseded by entirely new lines of attack.
,.
Declaring a set of identifiers Reading data - n - no. of columns or r o u in mtrix (alny8 an odd no.) p - no. o f f i r s t ele~nt ~o be l o o a t e d m - no. of lest element to ~
•e
located
/ Declaring further identifiers dependant on data
-~oe~ure D~st;
~
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b
This procedure is to calculate ~he distance between
locations; inte e r s , t I;
~
a~a~ y,x[l:2~; I tUUtll 2 do
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~Cal~lating distance between l~ationm in ga%rix If ~:O then beKln x[i]:-s| ¥[l]:-n end e-'~se be~'-xt17:-s+1; y [ l ] :-t end - end; D"T~sqrt((y[1].y[2])?2 + ( x [ 1 ] - x [ 2 ] ) 7 2 ) end; ~'~2; l:-a/~+O 5; if p#l then goto A; PRINT 1,5,o); SPACE I-~; P R ~ , ~ - ~ ; NEWLINE I ; EL 1 ~'1; A:for b:-1 a~ep I un~ll a do L b :=0; L 1"~=1| I f ~ - T the~n-~-p~]--else f o r w:-I s~ep I until p.l do
Resdln~ locations of a ~ ~Iocm%ed elemsm%s
~Or e : -s p~ e p s t e 1 Ut1~il m dO ~_~ f=-Ti~I ~ unt-f.__.! e-1 ~_o ,~[J] "DATA; S"DATA;
i, Re~dln~ numbers of sta~mr~ Jo~a-~eysbetween element to be locate~
A~:~lfor-eln:.(if S # 0 then eros else 1 ) step 1 until e.1 do beK-r~_or ~ . ~ E L eln I-I ,EL[eln] -n: "~[eln +l,EL[eln +n do ~ s i n if i~>a or L[~'~ # O then - - - ~ e ~ n ~ s t [ l s ] :-IO0~R~OO;LOc[L~] ~; OtO Skip e n d e ~ e c° E6~tn--"~:~O; Ld[l ] :-Ln; for eld:=Iste 1 until e-I d o ~en
~x~
~Locatlng first elemn% in Imtrix and ~r~tt*~ it8 l~atlon no.
D:'O else Dlst;
[eldT"4~
and previously located element8.
2. Reading guide no. 'S' which 8how thane, of elemntm of the lame aetivl~ already ic~ate~ •
wCaloulatin~ and 8to~in~ coats of a l l ~ossible temporary l ~ t i o m l ~ elemmt
end;
E6~t [LN] :-c; Loc [LN] :=Ln Skip: ~ + I end end|
~:-L~-I| MIN:- coati1]; l:=Loc[1]; for U41-2 8~eplte 1 until LNT do be~-'i~-If c o ~ - - ~ ] < ~ I N then --~in MIN := cos~T~]; end'
I:-Loc[L~]
o~In~
.inre~ colic ~ d .electl~ leapt ooetl~ looatloa
--
PAINT e,5,0 ; SP'~"E~ ; PRINT(I,5,0 ; NEWLINE(1); EL e] :--l; L[IJ :-e; end~
Fig. 13. Algol programme.
Pr~t ~ag re|ult ~ m ~ e n t l ~ positioning e l e c t in selmoted l~atinn
138
B. Whitehead and M. Z. Eldars t ; 32; 1:300;1; 9)o; 1 903;2; I ')O;lUOC;lO 23;2~;23;23J 23;23;23;23; b;5;5;5;I ;;I
......
No. of colu~a or ro~ in" It~ix No's, of flrmt and last e3-mnt to be leeate~.
If Sell tleEenta have been
pr~located, the nora. of their l o c a t i ~ u should ke stated in e l a ~ t no. order b~fo~ giving further data.
;0;3; .~; 1"Jt~3; I ; I;o;
5 ; 5; 5; 5; l'~J;U2; IOiJO; ]300; 2; 5 and i0 ~e no,a. of at~s~ jour~ betmen elamnt to be looated an~ 5; 5; 5;5; I'); It); I030; I~YJ3; IOOO;3; pr,,vio~ly located ela~t| 5; 5;5;5; I~; 10; IOO~; IOOO; I O:)U; IO!>0;4 ; IO00 Is la ladle no. t to t~e that t~ ele~nt ~ l~ated ner~ to ths 5; 5;5;5; II; IO; 1ooo; 1OOO; 1OOO; I r)oo; !OO~}; 5; llmedialaly ~ e v i o ~ e l e l n t 5;5;5;5;1u;IO;I ;I; I;I;I;I;O; 2 i. tlm ~ide lto. 's, 5;5;5;5; I0; Ir~; I ; I ; I; I; I; I ; !000; I ; 5; 5; 5;5; 13; If]; I ; I ; I ; I ; I ; I; I(300; 1(9~0;2% 5; 5;5;5; I 3; IU; 1 ; 1 ; 1 ; I ; I; I ; IUt)O; I000; 1000; 3 ; 5;5;5;5; !3; 11~; I; I; I ; I ; I ; I; 19C3; I ~:)Z; IZ~2~; I L~,C;4; 5 " 5 ; 5 " 5 ; 1 )'1 ';1 ' 1 ; 1 ; 1 ; 1 ; 1 "10~0" l(JOO;1,300; 1!)%)0' 9 )0(3;5 2~21~'214" ~'616~6.616;6.6:6.6191616 0
2]2;2;2;4:4:6;6;616;6;6~6:6~6;6;6;6~1Joo; 1 2; 2; 2~'2' 4 ~'~'6; 6 ' 6 " 6 ; 6 ; 6 j 6 ~ 6 ; 6j 6 ; 6 J 6 lo0o~1 ~o3.2; ~; ;1~'113;3~'6;6~'6~'6;6;6;6.6 6 6 ; 6 1 6 { 1 6 ; 1 6 ; 1 6 6 ; ; ; ~ ' ~ ; 3 ' 3 ' ~ 6 ; 6 : 6 ~ ' 6 ; 6 ; 6 ; 6 ~ ' 6 , 6 ~ 6 ; 6 ; 6 ~ 6 ~6 ~6]F3oo;~; I ; t ; I ~ I ;3~3~6;6~6~6;6;6 6 6;6;6;6;6;16;16116;100'3;10~)~ 2
I;I;I;I;9;9;I;I;I ;I;Iji;I;I;I;I I;I ;3;3;3;~J~;2;0; I; I j 1; I ; 9 ; 9 ; 1 ; 1 ; I ; 1 ; I ; 1; 1 ; 1 ; ~ ; 1; I ; 1 ; 3 ; 3 ; 3 ; 2 ; ~ ; ~ ; 1000; 1; 1; 1 ; 1; 1 ; 9 ; 9 ; 1 ; 1 ; 1; I ; 1 ; 1;1; 1; 1; I ; I ; 1 ; 3 . ; 3 J 3 ; ~ ; ~ ; 2 ; lOOO; 1"J00;2; 6;6;6;6;5;5;0;0;0;0;0;0;0;0;0;0;~;0;2;2;2; 1 ; l ; I ;4;4;Z~;0; 6;6;6; 6; 5; 5;O;O;O;O;O;O;O;O;(~;O ;0;0;~; ~; 2; 1 ; 1 ; 1 ;4;~;~; I000; ~ ; 6j6;6;6;5;5;OjOjOjO;OjOjO;O;O;O;O;O;2;~;~; ~ j i ; ~ 4;~I;A~j i000; i000;~ ; 6; 6;6;6j 5; 5;O;O;o;o;O;O;(J ;0 ;0 ;0;3;0; 2;2;~; ~ ; I ; | ;~;~I; ~; I(~0; fo00; ~000; 3; 6;6;6;6;~; 5;Ojujo;o;o;o;o ;0;0;0;0;0;2;~2; I ; I j I ;~I;~; L~; IO00; IO00; 1(}Ooj ? Ooo~ ;*
Fig. 14. Data (part of).
Future work may result in a blending of the computer approach described above with either new or existing work, e.g. Moseley[10, 11], to produce a composite approach to the layout of multi-storey buildings. The main effort in the approach described was restricted to single-storey buildings because of the complicating factors that stairways and lifts necessarily entail, for instance :-(a) A stairway or lift to an area vertically above or below cannot be regarded as a close link however near the head and foot of that vertical connection are to the rooms concerned[10, 11]; the time or energy required to change storeys is equivalent to that required for a considerable horizontal distance. (b) Costs would be impossibly high if there were more than a very limited number of points of vertical access and it is generally considered necessary for these to be in the same plan positions on most floors of a building; these factors increase the difficulty of obtaining close floor-to-floor links and suggest that only the weaker connections should be catered for by vertical access. If it happens that activities are closely linked in groups of a similar size, each of which can reasonably be flitted into one storey of a possible building and if the links between the groups are relatively tenuous, the dividing of activities between storeys is simple. In other circumstances an unsolved problem seems to remain.
(c) If the positions of vertical access are prespecified the problem becomes similar to one of single-storey layout, but if the positions are regarded as items to be optimised the problem becomes very complicated. These are, however, points to be tackled in future work rather than insuperable obstacles. Further programming work also needs to be done to cope with the case in which several existing buildings or pieces of accommodation (e.g. existing buildings in a growing group) need to be pre-positioned at definite, separated locations in the matrix, the other activities then being positioned both between and around the pre-located activities in a pattern designed to give the minimum cost. Perhaps the most important obstacle to the practical application of numerical methods of analysis is the lack of data mentioned above. If real progress along the lines set out is to be made, a comprehensive set of studies should be carried out to establish the movement patterns for typical types of building and to establish, as far as possible, the values of modifying (or over-riding) factors in those particular types of building. Architecture, in company with many other disciplines and professions, is moving towards systematic design and the use of computers as an aid to numerical analysis. The arrival of the day on which logic and mechanised computation have replaced empiricism in the field of layout planning should be hastened by all possible means.
REFERENCES 1. R. MUTHER, Systematic layout planning. Industrial Education Institute, Boston, Mass. (1961). 2. P.A. STONE,Building economics. Chap. 6 of Land Ownership and Resources, Cambridge (1960). 3. P.A. STONE, Factory building, evaluation and decision: Better Factories, pp. 249-260. Institute of Directors, London (1963). 4. M. Z. ELDARS,An approach to the optimum layout of single-storey buildings from the point of view of circulation with special reference to operating theatre suites. Ph.D. Thesis. University of Liverpool (1964).
The Planning of Single-Storey Layouts 5. B. WrUrEnEAOand M. Z. ELOARS,An approach to the optimum layout of single-storey buildings. Architects' J., 17 June, pp. 1373-1380 (1964). 6. M. VAN M~NTS, Internal traffic in the general hospital. (1963).
Architects' J., 3 July, pp. 27-30
7. A. G. Shaw, The purpose and practice of motion study. 2nd edition, Columbine Press (1960). 8. R.J. PHILLIPSand G. A. ArKINSON,A three dimensional room layout model developed at B.R.S., R.LB.A. Journal, 70, 19-21 (1963). 9. A. J. BUTLER, Model design techniques. B.R.S. current papers. Design series no. 21 (1964). 10. D.L. MOSELEY,A rational design theory for planning buildings with particular reference to circulation, Ph.D. Thesis, University of Liverpool (1962). 11. D.L. MOSELEY,A rational design theory for planning buildings based on the analysis and solution of circulation problems. Architects' J., 11 September, pp. 525-537 (1963). 12. ANON,Planning accommodation for hospitals and the transportation problem technique. Editorial on work of Bruce Archer. Architects' J., 17 July, pp. 139-142 (1963). 13. B. WHITEHEAD,Computers in building. Letter to Architects' Journal, 31 July, p. 214 (1963). 14. P.H. L~vly, Use of graphs to decide the optimum layout of buildings. Architects' J., 7 October, pp. 809-815 (1964). 15. B. WHITEHEADand M. Z. ELDARS, Optimum layouts. November, p. 1223 (1964). 16. P. H. LEVlN, Optimum layouts. 1223-4 (1964).
Letter to Architects' J., 25
Reply to (15) in Architects' J., 25 November, pp.
17. E. L. BUFFA, G. C. ARMOUR and T. E. VOLLMANN,Allocating facilities with Craft. Harvard Business Rev. 42, 136-158 (1964). 18. J. J. SOUDER et al., Planning for hospitals: a systems approach with computer-aided techniques. American Hospital Association, Chicago (1964). 19. J. J. SOUD~Rand W. E. CLARK,Computer technology: new tool for planning. A.LA. Journal, October, pp. 97-106 (1963).
139
Build. Sci. Vol. 1, pp. 127-139. Pergamon Press 1965. Printed in Great Britain.
I
UDC
Ba4
I
721
The Planning of Single-Storey Layouts B. WHITEHEAD* and M. Z. ELDARS*
action. Initial capital costs tend to loom large in the minds of the client and architect, but the costs which continue month by month, t h e ' costs in use ', tend to be hidden by their piecemeal nature and by the lack of a readily visible alternative as a standard of comparison. These and perhaps other reasons lie behind the apparent tendency of the architect to undervalue, in relation to other facets of the design, the effect on total costs over the life of the building of the organisation of activities within the building and their associated human movement costs. Obviously the design of any building must be a compromise between many factors and restrictions. Financial resources and the size or shape of the building site set initial limits; within these limits it is necessary to provide an environment suitable for human beings to work in and it is also accepted that human movement within the building should be as efficient as is compatible with the other design restrictions. Lack of data on this latter aspect and, as pointed out above, lack of information on its relative importance, often, however, lead to lipservice being paid to it. An indication of the financial relationship between initial and running costs is given by Stone [2] who states that ' At current rates, service staff cost about £500 a year; this is equivalent to an initial cost of £10,000. It is, therefore, worth spending up to this amount to eliminate the need for a liftman, stoker or cleaner '. Stone [3] also states, for factory buildings, that ' labour and material costs are likely to be so large compared with building costs, that comparatively small proportionate savings in these fields are likely to more than repay for the costs of rebuilding '. The relative importance of initial and running costs is obviously not the same in all types of building, but a pointer may be taken from studies in a hospital operating theatre suite [4, 5] where the cost breakdown was found to be : I
INTRODUCTION IN manufacturing industry the detailed planning of the layout of production floors and their ancillary services has long been recognised as being of vital importance to the ultimate efficiency of the working unit. Techniques were provided by the early 'industrial engineers ', which could be used as a basis for solving industrial layout problems and Muther [ 1] has recently attempted to systematise the use of such techniques in layout planning to ensure that all the various factors, objectives and physical limitations are given due weight. The most essential feature of any study designed to improve upon an existing situation is, of course, the use of data from that situation in the analysis and synethesis leading to the proposed solution. Where there is no existing situation, e.g. where a department to manufacture an entirely new product is to be set up, data from the product design and work study departments giving the necessary sequence of operations, together with information from the sales department setting out the estimated quantities required, will be used as the best available substitute. In building, on the other hand, possibly because of the division between the architect and the builder, there has been a tendency to make relatively little use of feedback information, Emphasis has tended to be placed on the development of original designs and in many cases attempts have been made to fit the functional square peg into the aesthetic round hole. Buildings, once erected, have been regarded as completed jobs rather than as the base-line from which to proceed in the design of other buildings of similar type and, consequently, there has been little attempt to obtain information on how well, or badly, particular features of a design have operated. Failures in some facets of a building are, however, much more dramatic than failures in others and draw, perhaps undue, attention to themselves. If the structure gives way or the roof leaks, remedial action has to be taken, but, if the arrangement of spaces in the building is such that the cost in salaries and wages of using the building is, say, 25 per cent above what it need be with an alternative arrangement, there is no urgent pointer to the necessity for
Table 1. Approximate percentages of total annual cost.
Buildings and equipment (amortized at 5~ of initial cost per annum) Maintenance, cleaning, heating, lighting and materials Staff, salaries and wages
7 22 71
The cost of human movement between rooms was found to be approximately one third of the total
*Department of Building Science, The University, Liverpool 3. 127
128
B. Whitehead and M. Z. Eldars
salary cost of staff time, that is, about 23 per cent of the total annual cost of the suite, thus showing the large potential for savings in that sphere and, in default of other equally measurable and important criteria, presenting a strong case for the use of the circulation of people as the prime data in deciding the layout of that type of building. Some industrial production areas, where the large scale manufacture of one type of product or the great weight of material to be moved enforce a very definite path of movement upon the process, may be regarded as exceptions in that human movement will in these cases be a subordinate factor. Most other types of building, on the other hand, e.g. office blocks, warehouses, houses and schools are likely to be found to approximate more closely to the pattern shown by the operating theatre suite mentioned above. For the purpose of this paper, then, although it is realised that in individual cases some factors must modify the layout or even be of paramount importance, human movement is regarded as being the prime data in layout problems. The effect of this assumption is to simplify the problem considerably since the movement of people in buildings similar to the one to be designed can be objectively observed, recorded in numerical form and analysed. In planning a layout the architect normally starts by making a layout diagram. The diagram consists of different activities or cells connected to each other by proposed circulation routes, sometimes differentiated according to degree of importance. The design then proceeds by trial and error until a compromise is reached which more or less satisfies all the known factors and restrictions. It would be possible in many cases for the architect to carry out an investigation in a building of similar type to the one he is designing in order to obtain numerical data on which to base the locating of activities in relation to one another, but the fee structure of his profession does not encourage so detailed an approach and the means of analysis of such data have not been available. The position has changed somewhat in the recent past in that, for instance, the Building Research Station [6] has started to collect data on the movement inter-relationships between the various parts of a hospital. An extension of this approach could lead to ' potted data ' on the relationships between different types of activity in specific situations becoming available for amendment and application to particular problems. Several attempts have also been made to provide a means of analysis of such data and the remainder of this paper will largely be concerned with a summary of some of these approaches and a more detailed description of one.
BACKGROUND The traditional techniques for layout planning are, as described by Shaw [7] and others, the flow and string diagram, the process chart, sometimes
combined with a flow diagram, the use of templates for trial layouts within a storey and of models for more sophisticated single and multi-storey work. Recent work on the use of models has been done by' the Building Research Station [8, 9 I. it was always realised that the final result must, of necessity, be a compromise between many factors, but the work of Muther (above) has probably been of considerable assistance in ensuring a logical pattern of work and allocation of priorities. Moseley [10, I I ] attempts to find a rational basis for deciding the shape of multi-storey buildings and for allocating accommodation to optimum positions in such buildings. He concerns himself largely with interfloor movement rather than with movement on one floor and adopts a simplifying assumption to facilitate the use of linear programming in finding the optimum location of each unit of accommodation. This is basically that ' all journeys are made from a hypothetical " mean point of origin '~ to the location under consideration ', in effect through the " vertical circulation point '; the object of this assumption is to circumvent the difficulty caused by the fact that a move of one unit of accommodation from one position to another affects the ' cost ' inter-relationships of all the other units and, in the absence of this assumption, prevents a single access distance (or circulation cost) being set for each possible location. Archer is reported [121 to have 'conceived the idea of turning the transportation technique inside out and using it to optimise the locations of the points of origin instead of the movements between them '. In a similar way to Moseley, he assigned a value to the importance of the connection between each pair of activities, then set up a topological model based on the expected shape of the building and assigned distance factors between the various possible locations in the grid. A transportation type linear programming technique was then used to produce the allocation of activities to locations which would give the minimum communication cost between one of the activities and all the others. As pointed out in correspondence [13] the answer could only be a partial one since it did not consider the inter-relationships between the activities and, whilst it might be the optimum from the point of view of the given activity, it might be a very bad answer for the building as a whole. If, for instance, in a hospital the operating theatre was regarded as the activity around which the planning of the hospital was to be optimised, it might well be foundthatin t h e ' optimum ' answer, the out-patient department was at one end of the hospital and the X-ray department at the other, despite the fact that these two had a very close relationship one to the other. Further trials using other activities as the central point might well give irreconcilable answers. It would, in fact, seem that, as Moseley found, a move of one activity from one location to another changes the ' c o s t ' inter-relationships of all the other activities and therefore prevents the assigning of a single cost to each location (a necessary condition for linear programming).
The Planning of Single-Storey Layouts
129
importance should not cut across the line(s) already on the ' g r a p h ' . The shape may be altered to accommodate each addition, but any line which cannot be added without cutting across other lines is omitted. Lines in the final network represent direct room-to-room connections. Areas of rooms
Moseley did not use a computer but realised the obvious applicability of such a tool to his approach. Archer regarded a computer as an integral part of his technique. The approach by Whitehead and Eldars[4, 5] described later in this paper, also could not be economically carried out without the use of a
Sink room
E
Operating theatre
Operating theatre
Anaesthetic room
Anaesthetic room
Minor theatre or recovery room
Theatre
Emergency theotre
superintendent's room room
Surgeons' dressing store Surgeons' room room Nurses ~ room
Sisters'
room Kitchen
Jf 0
5
I0
20
3O
Feet GROUND
FLOOR PLAN
Fig. 1. String diagram of movements of state enrolled nurse during one day's duty in existing operating theatre suite.
computer. Leven[14], on the other hand, recently put forward a technique based on ' graph theory ' which is intended to require pencil and paper only. The basic idea is that, if two points representing the two activities with the strongest connection in a building are joined by a line, then other relationships subsequently added to the diagram in order of
and other considerations are taken into account in transforming the network into a spatial layout. In correspondence[15, 16] it was pointed out and agreed that although the approach was simple, it would not be feasible to use it to decide the layout of large numbers of activities because of the complexity of the ' graph ' and the time consumed. The
130
B. Whitehead and M. Z. Eldars
technique uses only a ranking of the order of importance of connections as data and it is evident that, once a link has been drawn into the ' graph ', that link is (until the spatial layout stage) regarded as being equally as important as those previously
Buffa, Armour and Vollmann[17] working in U.S.A. report the use of a computer programme which starts with an arbitrary or existing layout grid and exchanges pairs of activities or elements until the exchange which saves the most in terms of
Emergoncy exit Anaesthetic-room
Anoesthehc- room :
,j
Operating theat
Operahng theatre
Sink-roe
Sink room -
Operating theatre
Operohng theatre
,!jj Disposal corridor
Disposal corridor II Anaesthetic
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_[ccm
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~
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~
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: i ,i
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i
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m
i:
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~J
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f
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Fig. 2. String diagram of theoretical movements of state enrolled nurse during one day's duty in possible operating theatre suite,
drawn, despite the fact that their importance may really differ by a factor of ten or more. Also it cannot, using ranked data, take the total importance of the connections between one activity and all others into account.
distance or cost has been found. A permanent change is then made in the proposed layout and a further set of pairs of exchanges is evaluated. The process is continued until further exchanges yield no extra savings. The programme is said to be
131
The Planning of Single-Storey Layouts economical in computer time and to yield considerable savings. Souder and others[18, 19] also working in U.S.A. suggest the possibility of on-line architect-computer communication using an oscilloscope to display data on the workings of existing buildings. Modifications to simulate the anticipated activities in a proposed building would be made by drawing on the oscilloscope face with a light pen and the ' costs' of the proposals would be computed and displayed. It is obvious that such a system would marry the intellectual capacity of the man to the storage and calculating capacity of the computer, but might well be very expensive in computer time. A COMPUTER-AIDED A P P R O A C H It was obvious when work commenced on this approach that current work using linear programming could, as argued above, only optimise for the location of all the activities in a building in relation to one point. It was, therefore, considered necessary to evolve a method which would take into account as many of the inter-relationships between activities as possible. A considerable number of string-diagram studies had already been done to determine the pattern and volume of movement in a typical hospital operating theatre suite and empirical attempts had been made by traditional techniques to evolve a layout which would both rninimise the necessity for movement in a re-arranged suite provided with similar accommodation and incorporate new facilities suggested on movement-economy and medical grounds (figures 1 and 2). For most categories of staff in the suite it was found to be possible to achieve considerable reductions in the movement necessary but it was impossible to say how closely the layout derived approached the optimum because of the innumerable variations which it is possible to make in laying out a number of units of accommodation and the consequent work in calculating the total cost of each arrangement. The data collected in the string diagram studies were used as the basic material around which to build the computer approach, but, to apply the technique to a different type of accommodation, it would be necessary either to take observations in a building of similar type to the one to be designed or to make use of the best available estimates. The final result can, of course, reflect no more accuracy than is contained in the original data and the rougher the data, the less worthwhile it becomes to use refined analysis techiques. In order to avoid bias in the data, observations should be made over a representative period (i.e. a period of time covering at least one complete cycle of the activity concerned) and for each type of staff employed.
General preparation of data Assuming that data have been collected, the following steps are suggested as being necessary to prepare them for any form of computation :--
1. The data are plotted as string diagrams for each individual type of staff. 2. The heaviest concentrations of movement shown on the string diagrams are critically examined with the aid of notes taken during the observations to determine whether the reasons for the movements can be removed by changes in organisation or by changing the types of accommodation provided. 3. The data are modified to take any desirable changes in organisation or accommodation into account. 4. The number of journeys between each pair of points at which work is done is counted for each type of staff. (The terminal points of journeys may, on different scales, be points within one room, whole rooms or even whole buildings if the technique is used to optimise the layout of a complex of buildings. For convenience these terminal points will hereafter be referred to as ' activities '.) 5. The number of journeys between each pair of activities for each type of staff is multiplied by the normal number of that type of staff employed. 6. The number of journeys for each type of staff is modified by a factor representing the relative cost (salary plus overheads) of that type of staff in relation to the average. For example :--
Table 2. Total annual cost (salary and overheads) £ (assumed figures)
Factor
2400
1-6
1475 750
1.0 0.5
Surgeon Average of aU theatre staff Student nurse
If, then, a surgeon and a student nurse both made one hundred actual journeys between two activities the result, weighted according to cost, would be :--
Table 3. Standard Journeys
Surgeon Student nurse
100 x 1-6 100 x 0-5
160 50
7. The total number of modified ( o r ' standard ') journeys between each pair of activities is obtained by adding together the totals for each type of staff. 8. At this point factors other than movement can be introduced into the calculation if, in the particular situation, it can be agreed what their values relative to that of movement are. If, for instance, in case of fire, it is essential to get from point A to B in the minimum time, then the number of standard journeys between A and B can be modified to take this into account.
132
B. ~'/litehead am/M. Z. Eldars
9. The totals can now usefully be set out in an association chart (figure 3) showing the interrelationships between all activities in numerical form.
Further preparation of data for programme described Up to this stage the preparation or standardisation of the data has been such as would be required for almost any form of computation. The follow-
It is suggested that this order of importance be determined as follows:-(a) The total number of standard journeys between each activity and all others is calculated from and written into the association chart (figure 3). The activity which has the largest number of contacts with all other activities is chosen as the starting point for the building of a new layout, e.g. activity 13 in figure 3.
Fig. 3. Association chart.
ing steps are more particularly related to the ' Algol ' programme written and tested by Eldars :-1. Because of the nature of the problem, namely that a move of one activity from one location in the layout to another affects the inter-relationships of all the activities, it is essential to solve the problem step by step. It is therefore necessary to make the most important decisions first, in this case to locate the activities in a plan layout (or 'locations matrix ') in order of their importance from the point of view of the factors evaluated by the figures o f ' standard journeys '.
(b) The second activity to be positioned in the new layout is taken to be the one which has the largest number of contacts with the first selected activity, e.g. activity 12 in figure 3. (c) The third activity to be positioned is the one which has the largest number of contacts with the first and second activities combined, e.g. activities 9 or 14 in figure 3 (the two theatres are identical). (d) The order in which all the remaining activities will be dealt with by the computer is determined in a similar way, taking into account the relationship of each activity to all the previously selected activities.
The Planning of Single-Storey Layouts
(i.e. a number much higher than any of the calculated relationships) as the inter-relationship between elements in the same activity; this ensures that the computer will locate the elements next to one another and so avoid the splitting in the computer plan of units of accommodation which are in practice indivisible. It should be noted that the process of apportioning the number of standard journeys to individual elements is subsequent to the determining of the order in which the activities (and hence the elements) will be located by the computer in a plan layout. The order is not then affected by the differ-
2. To arrive at a reasonably realistic answer it is necessary to take the areas required for the various activities or units of accommodation into account. It is assumed that the area required for each is determined by means outside the scope of this paper and that each area includes an allowance for circulation. Moseley[10, 11] suggested 10ft x 10ft as a convenient unit floor area (i.e. the area of a small room) and this is used in the following example. It is then necessary to (a) find the number of units of floor area (or ' elements ') required for each activity.
o-1o~:.~:,~3++.p~,,,~ T.eo,re \ P q..41::l
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journeys
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,
Fig. 4. Relationship Matrix.
(b) determine the number of standard journeys between each pair of elements from different activities; this may be calculated as (Total number of standard journeys between two activities)
(Number of elements in activity A x Number of elements in activity B)
journeys[ Activity A
[
Activity B
4 × 2 ;t;2?Lry~)t_......~ Activity A (4 elements)
Activity B (2 elements)
(c) Set a very high number of standard journeys
ing relationships which the inclusion of the number of units of floor area in the calculations throws up. 3. Any activities which are to be pre-located ~hould be specified. 4. The final data showing the number of standard journeys between each pair of elements can be set out in a 'relationship matrix' (or expanded association chart) (figure 4) and punched into paper tape. The paper tape is then ready for feeding to the computer with a programme of instructions.
Automation of data preparation It is probable that future work will extend the computer programme described below to cover a considerable amount of the manual working-up of
134
B. Whitehead and M . Z . Eldars
data set out above. The relatively raw data to be fed into the computer would then be : - 1. Salary and overhead costs of each type of staff. 2. Number of actual journeys between each pair of activities made by each type of staff. 3. Number of each type of staff employed. 4. Number of units of floor area required for each activity. 5. Any restrictions or over-riding factors. The present computer programme 1. A n illustrated d e s c r i p t i o n - The principles of
the process through which the computer goes in locating a set of activities in relation to one another can be illustrated by an example representing a rearrangement of accommodation in an existing operating theatre suite. To avoid misunderstanding, it should perhaps be stated that this set of accommodation does not necessarily contain all the facilities which might today be regarded as being desirable in an up-to-date suite. This has been done
M
Fig. 5. Locations matrix with one activity prelocated.
to maintain as strict a comparison with the existing suite as possible. The suite contains 21 rooms (which can in this case be equated w i t h ' activities ') * The cost of each temporary location is determined by:-(a) calculating the distance (assumed to be in a straight line) from the centre of the location to the centre of each occupied location. (b) multiplying each distance by the appropriate number of standard journeys between the particular elements. (c) adding the answers. The assumption that the distance between the centres of two locations can be measured by a straight line is, of course, a simplification. The actual walking distance would be affected by the positions of doorways and the convenience of circulation routes, but it is self-evident that, if the straight line and actual circulation costs for a certain layout are compared, then the closer the actual approaches the straight line cost, the more efficient are the circulation routes employed. The ratio (actual circulation cost)/(straight line circulation cost) was calculated by Eldars for several layouts. Those layouts which had been empirically designed produced ratios approximating to 1-20; those which had been derived from the computer output gave ratios of about 1-05. It would, therefore, seem that, for efficient layouts, the straight line distance is a sufficiently close approximation to justify its use in calculations.
Second activity (elements 5 and 6) ~'-~ First activity (elements 1,2,3 and 4) f Third activity (elements 7,8,9,10,1t and 12
•.>
Fig. 6. Locations matrix with 3 activ#ies located.
and the total area can, as partially illustrated in figure 4, be broken down into 55 units of area or elements. Suppose then, that a locations matrix (figure 5) with, say, 39 squares per side is set up in the computer's information store, each square being recognised by its store number, that each of the 1521 squares can be used as a possible location for one element, that the matrix is likely to be adequate in size to contain the final plan layout and that the activity which is first in order of importance is to be pre-located in the centre of the locations matrix to form a reference point around which to build the rest of the layout (figure 5). There is no problem in positioning the second activity when only one activity has been pre-located since it must be next to and can be on any side of the pre-located activity. The positioning of the third activity in the optimum location requires some calculation and the complexity of the decision as to where to locate each subsequent activity increases as the pattern builds up. I f it is assumed, to give the problem reality, that the elements comprising three activities have been located, the next step will be to supply to the computer the element number of the first element of the fourth activity (element no. 13) and the numbers of standard journeys between this element and previously located elements. The programme is so arranged that the computer will then temporarily position element no. 13 in a location adjacent to the locations already allocated to other elements in the first three activities and will calculate the total ' c o s t ' of this temporary location.* The cost will be stored in the ' memory ' of the computer and the element will then be moved in turn to all other possible locations on the immediate perimeter of the locations already occupied (figure 7) for a similar calculation to be made. When all the locations have been costed, the computer will compare the stored costs, select the least costly location and permanently position the element in that location. The second and subsequent elements of the fourth activity will be dealt with in a similar way, but, because of the high dummy relationship between the elements of the one activity, they will,
135
The Planning of Single-Storey Layouts
[[I m
][I
Fig. 7. Locations matrix showing all possible locations of element 13. PROGRAM REF NO ELEMENT NO
LOCATION 11 21 31 41 51 61
71
lOJ 111 lZl 131
141 151 |6| 171 lOl 211
NO 7611 7601 722t 7211 7621 723J
8001 5011
81 91
191 201
LAYOUT oPTIMISATION
•
8391 5401 7991 838I 6831 6841 6441 6451 6821 6431 7631 7241 7641
the computer as a series of storage positions and the form of the matrix has to be interpreted from the computer output (figure 8). The left hand column of figures in the output gives the element numbers and the right hand column gives their respective locations. The interpreted matrix form is shown in figure 9. The groups of elements forming whole activities can now, by reference to the relationship matrix (figure 4), be outlined to show the positions of whole activities (figure 10). The final step in the process, the conversion of the diagrammatic, theoretical layout into a practicable form is, and may well remain, an empirical process because of the difficulty of building every conceivable, material factor into a general computer programme. The necessity in some rooms for daylighting by windows in outer walls could possibly be built into a future programme but the particular requirements of specific situations, such as the need to maintain aseptic conditions in an operating theatre suite, would be entirely irrelevant to other buildings and, unless they could be expressed as restrictions in the data, would be best considered in an empirical stage. An assumption was made above that an allowance for circulation was included in the area allocated to each activity; it is at this stage that the allowance is separated in the form of corridors and other circulation spaces. Some amendments to the location of activities may be necessary to cover the specific requirements mentioned above but such amendments should be regarded as deviations from the near optimum computer solution and should, therefore, be restricted to the essential minimum.
Fig. 8. Computer output. (part of).
as a prior requirement, be positioned next to the first element and to one another, the exact location and shape of the room housing the whole activity depending on the strength of its relationship to other located activities. The elements comprising the other activities required in the layout will be positioned in the same way around the growing nucleus, the final location of each element depending on its relationship to each of the previously located elements. The completed locations matrix will only exist in
~ee~
Mole sta ~ chang. Work room ant ing and staff it~ cleon SUpply room 44 /' 43 46 47 !Sterile MediCOlstoreEntrance stotionl supply 55 42 41 138 35 45 q Medical Medical Anaesthetic Anaesthetic staff stoff room no. 2 room no. [ ChOn(Jh~ ~st rm, 4 0 rm 39 37 36 33 34 room 54
Nursd=l
18
17
Z
General theatre no.2 15 13
3
II
Ante-space 4
48 Nurse's longing and rest room 49 50 Sisle¢~ changirKj and rest room 5l
52
12
53
;eneral theatre ~o. I
7
9
3
IO
3crub-up room 16
S
14
(5
52
i
-~terilising room :>4 22
Sink room 19 20
Emergency theatre
25
28
30
Z9
31
Small theatre
23
I
0
21
I
I0
2?"
1
26
I
20
30
I
40
50
Ft
Fig. 9. Completed locations matrix.
Fig. 10. Diagrammatic layout derived from computer.
B. Whitehead and M. Z . ' E / d a r x
36
Suite e n t r a n c e ,
JMedical IMale J I JWork room JSterileJ 3uperin- Istore qJstaff / / lJo nd clean JsupplyI roomtendent'sI..,~.~r k ~lreStchanc~ingl anal-rOOm J 1 !upply room Iroom I
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i %t
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o
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i
IO
I
20
J
30
40
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50
ft Fig. 11. A possible first stage in the conversion of the diagrammatic layout to a practicable form,
Suite entrance IlL
Superin-J Male staff tendent~( rest and roomH changing rm. Work room and cleon ~. tu~lle, v~y supply r O0 room store k.~ i -~ ~ Nurse's station
I r o o m J staff I.Air
J Small theatre
I vrTI;o':'m lY? J II
I/I
1~1
Theatre no.2
IJiI]
5
[
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t ~
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tO
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I
~
Anaesthetic J
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~"d L Anaesthet'c
~__~1
.
I
I0
Theatre no. I
L
20
1
30
1
4.0
I
50
ft F&'. 12. A possible second in the conversion (ff the diagramatic layout to a practicable jbrm.
The Planning of Single-Storey Layouts Figures 11 and 12 represent two possible stages in the conversion of the diagrammatic layout to a practicable form. Assuming that the staff in the suite shown in figure 11 would follow the same traffic pattern, the actual circulation cost for that suite would be 28 per cent less than for the existing suite. Although figure 11 is fairly close to the theoretical layout shown in figure 10 it is possible that objections to the layout would be raised because of the ' less clean ' corridor separating the scrub-up, sterilising and sink rooms from three of the theatres. It is also possible that the weighting given in the data to a porter pushing a patient on a trolley ought to have been greater, in which case the computer answer might have been closer to that shown in figure 12. The actual circulation cost for figure 12 would, on the same assumption as for figure 11, be 23 per cent less than for the existing suite, a monetary saving of about £3000 per annum. Checks made by asking experienced hospital architects to produce minimum circulation cost plans for the same accommodation by empirical methods gave cost results no better than that for the existing suite, thus verifying the usefulness of the computer approach.
2. The Algol programme--The Algol programme (figure 13), when supplied to the computer with data (figure 14), will carry out the procedure illustrated in the previous section. The annotations to the figures describe the function and operation of the various parts of the programme and data. The time taken on the KDF9 computer, using the l~in .....
intc~er n,m,p,w,a,b,l,e,j,S,eln,eld,Lm,LN,LNT;real C,D,MIN; -'-n'~AD~TA; p :-DATA; m I-DATA • TEXT(ILAYOUT*OPTIMISATION~ ;NEWLINE(2) ; T~T[[EI~MENT-NO~);SPACE(~)~TEXT(~I~3CATID~"NG );NEWLINE I); be~in--lnte~er array L I :n~eJ,Loc[T:mx~ ,EL[I I~l IA 1:2 ; real a r r ~ cost[l : ~ ] , J [ 1 :m-l];
137
Kidsgrove translator, to locate certain numbers of elements is shown in table 4. Table 4.
No. of elements
21 32 41 55
Actual computing time
Overall time taken on computer
Min
Sec
Min
Sec
0 0 0 1
12 23 50 32
0 1 1 2
53 6 32 15
It is obvious that, although the time taken will increase more than in proportion to the number of elements added to the problem, the limit at which the extra time per element added would be uneconomically long has not been approached in the figures quoted. CONCLUSION The variety of approaches to layout planning problems indicates, firstly, that a substantial body of opinion exists which is not satisfied with the efficacy of traditional methods used by architects and others and, secondly, that new techniques are in a relatively early stage of development. It is certain that refinements to proposed methods are necessary and very likely that they will be superseded by entirely new lines of attack.
,.
Declaring a set of identifiers Reading data - n - no. of columns or r o u in mtrix (alny8 an odd no.) p - no. o f f i r s t ele~nt ~o be l o o a t e d m - no. of lest element to ~
•e
located
/ Declaring further identifiers dependant on data
-~oe~ure D~st;
~
n
b
This procedure is to calculate ~he distance between
locations; inte e r s , t I;
~
a~a~ y,x[l:2~; I tUUtll 2 do
rot $:-I s ~
~Cal~lating distance between l~ationm in ga%rix If ~:O then beKln x[i]:-s| ¥[l]:-n end e-'~se be~'-xt17:-s+1; y [ l ] :-t end - end; D"T~sqrt((y[1].y[2])?2 + ( x [ 1 ] - x [ 2 ] ) 7 2 ) end; ~'~2; l:-a/~+O 5; if p#l then goto A; PRINT 1,5,o); SPACE I-~; P R ~ , ~ - ~ ; NEWLINE I ; EL 1 ~'1; A:for b:-1 a~ep I un~ll a do L b :=0; L 1"~=1| I f ~ - T the~n-~-p~]--else f o r w:-I s~ep I until p.l do
Resdln~ locations of a ~ ~Iocm%ed elemsm%s
~Or e : -s p~ e p s t e 1 Ut1~il m dO ~_~ f=-Ti~I ~ unt-f.__.! e-1 ~_o ,~[J] "DATA; S"DATA;
i, Re~dln~ numbers of sta~mr~ Jo~a-~eysbetween element to be locate~
A~:~lfor-eln:.(if S # 0 then eros else 1 ) step 1 until e.1 do beK-r~_or ~ . ~ E L eln I-I ,EL[eln] -n: "~[eln +l,EL[eln +n do ~ s i n if i~>a or L[~'~ # O then - - - ~ e ~ n ~ s t [ l s ] :-IO0~R~OO;LOc[L~] ~; OtO Skip e n d e ~ e c° E6~tn--"~:~O; Ld[l ] :-Ln; for eld:=Iste 1 until e-I d o ~en
~x~
~Locatlng first elemn% in Imtrix and ~r~tt*~ it8 l~atlon no.
D:'O else Dlst;
[eldT"4~
and previously located element8.
2. Reading guide no. 'S' which 8how thane, of elemntm of the lame aetivl~ already ic~ate~ •
wCaloulatin~ and 8to~in~ coats of a l l ~ossible temporary l ~ t i o m l ~ elemmt
end;
E6~t [LN] :-c; Loc [LN] :=Ln Skip: ~ + I end end|
~:-L~-I| MIN:- coati1]; l:=Loc[1]; for U41-2 8~eplte 1 until LNT do be~-'i~-If c o ~ - - ~ ] < ~ I N then --~in MIN := cos~T~]; end'
I:-Loc[L~]
o~In~
.inre~ colic ~ d .electl~ leapt ooetl~ looatloa
--
PAINT e,5,0 ; SP'~"E~ ; PRINT(I,5,0 ; NEWLINE(1); EL e] :--l; L[IJ :-e; end~
Fig. 13. Algol programme.
Pr~t ~ag re|ult ~ m ~ e n t l ~ positioning e l e c t in selmoted l~atinn
138
B. Whitehead and M. Z. Eldars t ; 32; 1:300;1; 9)o; 1 903;2; I ')O;lUOC;lO 23;2~;23;23J 23;23;23;23; b;5;5;5;I ;;I
......
No. of colu~a or ro~ in" It~ix No's, of flrmt and last e3-mnt to be leeate~.
If Sell tleEenta have been
pr~located, the nora. of their l o c a t i ~ u should ke stated in e l a ~ t no. order b~fo~ giving further data.
;0;3; .~; 1"Jt~3; I ; I;o;
5 ; 5; 5; 5; l'~J;U2; IOiJO; ]300; 2; 5 and i0 ~e no,a. of at~s~ jour~ betmen elamnt to be looated an~ 5; 5; 5;5; I'); It); I030; I~YJ3; IOOO;3; pr,,vio~ly located ela~t| 5; 5;5;5; I~; 10; IOO~; IOOO; I O:)U; IO!>0;4 ; IO00 Is la ladle no. t to t~e that t~ ele~nt ~ l~ated ner~ to ths 5; 5;5;5; II; IO; 1ooo; 1OOO; 1OOO; I r)oo; !OO~}; 5; llmedialaly ~ e v i o ~ e l e l n t 5;5;5;5;1u;IO;I ;I; I;I;I;I;O; 2 i. tlm ~ide lto. 's, 5;5;5;5; I0; Ir~; I ; I ; I; I; I; I ; !000; I ; 5; 5; 5;5; 13; If]; I ; I ; I ; I ; I ; I; I(300; 1(9~0;2% 5; 5;5;5; I 3; IU; 1 ; 1 ; 1 ; I ; I; I ; IUt)O; I000; 1000; 3 ; 5;5;5;5; !3; 11~; I; I; I ; I ; I ; I; 19C3; I ~:)Z; IZ~2~; I L~,C;4; 5 " 5 ; 5 " 5 ; 1 )'1 ';1 ' 1 ; 1 ; 1 ; 1 ; 1 "10~0" l(JOO;1,300; 1!)%)0' 9 )0(3;5 2~21~'214" ~'616~6.616;6.6:6.6191616 0
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Fig. 14. Data (part of).
Future work may result in a blending of the computer approach described above with either new or existing work, e.g. Moseley[10, 11], to produce a composite approach to the layout of multi-storey buildings. The main effort in the approach described was restricted to single-storey buildings because of the complicating factors that stairways and lifts necessarily entail, for instance :-(a) A stairway or lift to an area vertically above or below cannot be regarded as a close link however near the head and foot of that vertical connection are to the rooms concerned[10, 11]; the time or energy required to change storeys is equivalent to that required for a considerable horizontal distance. (b) Costs would be impossibly high if there were more than a very limited number of points of vertical access and it is generally considered necessary for these to be in the same plan positions on most floors of a building; these factors increase the difficulty of obtaining close floor-to-floor links and suggest that only the weaker connections should be catered for by vertical access. If it happens that activities are closely linked in groups of a similar size, each of which can reasonably be flitted into one storey of a possible building and if the links between the groups are relatively tenuous, the dividing of activities between storeys is simple. In other circumstances an unsolved problem seems to remain.
(c) If the positions of vertical access are prespecified the problem becomes similar to one of single-storey layout, but if the positions are regarded as items to be optimised the problem becomes very complicated. These are, however, points to be tackled in future work rather than insuperable obstacles. Further programming work also needs to be done to cope with the case in which several existing buildings or pieces of accommodation (e.g. existing buildings in a growing group) need to be pre-positioned at definite, separated locations in the matrix, the other activities then being positioned both between and around the pre-located activities in a pattern designed to give the minimum cost. Perhaps the most important obstacle to the practical application of numerical methods of analysis is the lack of data mentioned above. If real progress along the lines set out is to be made, a comprehensive set of studies should be carried out to establish the movement patterns for typical types of building and to establish, as far as possible, the values of modifying (or over-riding) factors in those particular types of building. Architecture, in company with many other disciplines and professions, is moving towards systematic design and the use of computers as an aid to numerical analysis. The arrival of the day on which logic and mechanised computation have replaced empiricism in the field of layout planning should be hastened by all possible means.
REFERENCES 1. R. MUTHER, Systematic layout planning. Industrial Education Institute, Boston, Mass. (1961). 2. P.A. STONE,Building economics. Chap. 6 of Land Ownership and Resources, Cambridge (1960). 3. P.A. STONE, Factory building, evaluation and decision: Better Factories, pp. 249-260. Institute of Directors, London (1963). 4. M. Z. ELDARS,An approach to the optimum layout of single-storey buildings from the point of view of circulation with special reference to operating theatre suites. Ph.D. Thesis. University of Liverpool (1964).
The Planning of Single-Storey Layouts 5. B. WrUrEnEAOand M. Z. ELOARS,An approach to the optimum layout of single-storey buildings. Architects' J., 17 June, pp. 1373-1380 (1964). 6. M. VAN M~NTS, Internal traffic in the general hospital. (1963).
Architects' J., 3 July, pp. 27-30
7. A. G. Shaw, The purpose and practice of motion study. 2nd edition, Columbine Press (1960). 8. R.J. PHILLIPSand G. A. ArKINSON,A three dimensional room layout model developed at B.R.S., R.LB.A. Journal, 70, 19-21 (1963). 9. A. J. BUTLER, Model design techniques. B.R.S. current papers. Design series no. 21 (1964). 10. D.L. MOSELEY,A rational design theory for planning buildings with particular reference to circulation, Ph.D. Thesis, University of Liverpool (1962). 11. D.L. MOSELEY,A rational design theory for planning buildings based on the analysis and solution of circulation problems. Architects' J., 11 September, pp. 525-537 (1963). 12. ANON,Planning accommodation for hospitals and the transportation problem technique. Editorial on work of Bruce Archer. Architects' J., 17 July, pp. 139-142 (1963). 13. B. WHITEHEAD,Computers in building. Letter to Architects' Journal, 31 July, p. 214 (1963). 14. P.H. L~vly, Use of graphs to decide the optimum layout of buildings. Architects' J., 7 October, pp. 809-815 (1964). 15. B. WHITEHEADand M. Z. ELDARS, Optimum layouts. November, p. 1223 (1964). 16. P. H. LEVlN, Optimum layouts. 1223-4 (1964).
Letter to Architects' J., 25
Reply to (15) in Architects' J., 25 November, pp.
17. E. L. BUFFA, G. C. ARMOUR and T. E. VOLLMANN,Allocating facilities with Craft. Harvard Business Rev. 42, 136-158 (1964). 18. J. J. SOUDER et al., Planning for hospitals: a systems approach with computer-aided techniques. American Hospital Association, Chicago (1964). 19. J. J. SOUD~Rand W. E. CLARK,Computer technology: new tool for planning. A.LA. Journal, October, pp. 97-106 (1963).
139