THE ARUP JOURNAL

WINTER 1991/92 Front cover: Kwun Tong Bypass. Hong Kong. under construction (Photo: L. M. Lui) THEARUP Back cover: Clerestory detail , National Gallery Sainsbury Wing JOURNAL (Photo: Peter Mackinven) Vol.26 No.4 Editor Winter 1991/92 David J. Brown Art Editor: Desmond Wyeth FCSD Published by Deputy Editor: Ove Arup Partnership Helene Murphy 13 Fitzroy Street, Editorial Assistant London Wt P 690 Joanne Worrall 3 Kwun Tong Bypass, Ove Arup & Partners Hong Kong designed the structure. including Hong Kong foundations. columns. and precast segmental deck. for 3.7km of Klaus Falbe-Hansen elevated highway on the Kwun Tong waterfront, alongside Kai Tak airport in Kowloon Bay.

8 Soda ash project, Ove Arup were responsible for the civil, structural, building, Sua Pan, Botswana foundation, and infrastructure engineering of this new plant to Colin Dittmer, Ernie Hall recover industrial soda ash from a 150km2 wellfield in a remote corner of Southern Africa.

12 Communications and This survey of work by Arups' Communications and IT Group Information technology includes communications infrastructures for the Department of Education and Science head office; the new Toyota plant; Hewlett­ Packard at Bracknell; Cellnet, Slough; and Hambros Bank; as well as a study for London Fire Brigade.

16 Welbeck: Arup Economics & Planning examined the economic and financial economics and finance viability of two alternative proposals for reclaiming 325ha of Jim Nyhan, Jonathan Mitchell despoiled land in West Yorkshire, by landforming with colliery spoil and waste from local sources.

17 Fabric engineering: This new office block at London Wall 1n the City of London The Lee House experience allowed a team of Arup engineers to develop a 'fabric John Pilkington, Neil Noble, engineering' service for the architect, integrating the wide range of and David Anderson technologies available for use on building envelope elements into an overall design approach.

20 The National Gallery Ove Arup & Partners undertook the structure and services design Sainsbury Wing for the new building in Trafalgar Square. This article concentrates David Brunt, Alan Pepper on the rigorous environmental systems developed for the safe display and storage of some 240 early Renaissance paintings in a variety of media.

2 Introduction Kwun Tong Bypass, Kwun Tong Bypass is part of Route 6, the 18km Government's original plan, which put great high speed link between Hong Kong Island. pressure on completing the rest of the link. Hong Kong Kowloon, and Sha Tin in the New Territories. Phase II is a 2.3km dual three-lane viaduct. The 4.8km Bypass connects two tunnels: partly over water. with four elevated ramps Klaus Falbe-Hansen Eastern Harbour Tunnel between the Island and totalling 0.9km in length. Phase Ill is 1.4km long Kowloon, and the Tate's Cairn Tunnel to Sha Tin. with one 0.2km long ramp . Dragages et Travaux It was contractually split into three phases of Publics, a subsidiary of the French contractor which only II and Ill were tendered com­ Bouygues, prequalified in September 1988 in a petitively, Phase I being completed as entrusted 90/10 Joint Venture with Bachy Soletanche to work by the Harbour Tunnel contractor, due to tender for both phases, and asked Ove Arup & early completion of the tunnel. This opened for Partners Hong Kong to assist them during the traffic in July 1989, 18 months ahead of the tender period.

2

Phase II Expressway

Phase 111 Expressway

Phase II Works Area

Phase 111 Works Area 1000 metres

...

New Seawall

New KAI TAK Passenger AIRPORT Typhoon Shelter Ferry Pier

Airport Runway

Phase II tender design The 'conforming scheme' The erection technique envisaged in the con­ The alternative scheme The engineer for Phase II, Freeman Fox forming scheme utilized an underslung launch­ The alternative segmental scheme used two Maunsell (FFM), issued tender documents in ing girder for the precast segments of Section basic box types, a large one typically 12.?m October 1988. The tender period was six B. Although this method is efficient for the con­ wide with cantilevers for the carriageways, and weeks. In their 'conforming scheme' design, struction of long straight decks, it is not easily a small box typically 6.2m wide with cantilevers FFM had divided the viaduct into three sections: adaptable for strongly curved alignments. for the ramps. Where carriageways and ramps two geometrically complicated end sections A Dragages favoured the use of an overhead merged, the cross-section comprised large and and C. and a central, almost straight, section B. launching girder to erect the segments by the small boxes connected through 0.5m wide in parallel to Kai Tak runway and mainly over balanced-cantilever system; the girder could situ stitches between the cantilever slabs. The water. also be adapted to cope with the changing length of the box cantilevers varied according Sections A and C. with sharp, horizontal. 190m horizontal deck alignment. By pivoting it on two to the required overall deck width and the length radius curves and widening decks to accom­ sets of transverse running rails it would be of segments varied with span length. Limiting modate the slip-road bifurcations, were to be of possible to move it sideways and rotate it segment dimensions - in particular the max­ prestressed concrete, constructed in situ by the relative to the deck centre-line when placing a imum segment weight of 80 tonnes - were span-by-span method. The cross-section was a pair of segments. Based on this method, a fixed by Dragages so that it would be possible multi-cell box 25m-43m wide for the two precast segmental alternative design was to use, with only minor modifications, the carriageways, and a 6m-8m wide single-cell box developed for the entire viaduct. launching girder which had just successfully for the ramps; construction depth was 2.0m, completed the construction of the Viaduc de except for one ramp which clearance problems Sylans near Chamonix in France. reduced to 1.8m. Span lengths varied between The Phase II viaduct was divided into several 30m and 40m. independent expansion units, the length of Section 8 was to be in precast segments with which depended on earthquake design re­ match-cast epoxy-glued joints erected span-­ quirements and deck geometry. The longest by-span. The cross-section consisted of two were 240m, consisting of six 40m spans on the separate boxes. one for each carriageway. The straight central section B of the viaduct. At boxes were single-cell and 12 .Sm wide for most tender stage a detailed preliminary design was of Section B. but towards Section A where the carried out for one of these six-span units to deck widens to 2 x 1Sm. two-cell boxes were establish reliable and economical quantities per used. The construction depth was 2.25m and m2 of bridge deck for concrete, reinforcement the span length was 40m. and prestressing steel. The benchmark for The foundations consisted of 1.5m-1 .8m these quantities, with due consideration being diameter bored piles to bedrock, with pile given to the design standards of Hong Kong , lengths in the range 30m to 60m. was what Bouygues had been able to achieve for bridges erected in a similar way on design­ Comparing unit quantities in the three sections and-construct contracts in France. The quan­ of the conforming scheme showed a lack of effi­ tities found for the six-span unit were extra­ ciency in Sections A and C when compared with 2 polated and applied to all the remaining expan­ the precast Section B, where quantities per m sion units to provide quantities of principal deck were about 30% less. It was therefore materials tor the complete viaduct. clear that an alternative design extending the 3. Launching girder near junction In the conforming scheme. all bridge bearings use of the precast segmental construction of Phases II and Ill. January 1990. would be economically attractive. were of the mechanical pot type. The Arup 3 design used the more economical elastomeric bored piles. Our Phase II quantities for precast Dunng each of the (normally four) cantilevering bearings wherever possible, and pot beanngs segmental construction were extrapolated and stages, temporary Dywidag bars hold the last only where earthquake restraint was required or used for the Phase Ill deck. The savings in quan­ pair of segments in position until the epoxy glue where the vertical load exceeded 10 OOOkN. tities relative to the conforming scheme were has set. Then the permanent top cables are Only minor changes were made to the column again substantial: concrete reduced by 20%, installed and stressed, and the next palf of shapes during the tender phase. but the design reinforcement by 50% and prestressing steel by segments can be attached. The permanent resulted in reduced reinforcement quantities. 30%. However, there was one major obstacle cables were, in the alternative scheme. Arups carried out an alternative foundation to the alternative system and that was the lack anchored in the end face of the segments with design for the whole viaduct based on the of a works area for a precasting yard. Only 11 the 1nstallat1on and stressing of the cables reduced self-weight of the alternative deck. For Phases II and Ill were combined, and the works carried out from a platform supported by the the land-based pile caps barrettes were used, area set aside for Phase II became available. launching girder; in a three-day cycle this opera­ typically 1.0m x 2.8m in cross section, instead would a precast segmental solution be feasible tion became critical, and the contractor decided of the bored piles. A barrette - a rectangular for Phase Ill. Dragages decided to submit the instead to anchor the top cables in a rib inside pile constructed under bentonite using the alternative with their tender. but with the the box. The installation and stressing of the top diaphragm·wall technique - can be orientated qualification that the group was also awarded cables could now be carried out without the aid to resist design loads 1n the most efficient way, Phase II. of the launching girder, which could be moved resulting in reduced reinforcement quantities. The tender sideways to place a pair of segments on canti­ We proposed founding the barrettes in the Tenders were submitted 1n December 1988. lever 2 while the stressing was carried out on dense decomposed granite with SPT value Dragages were not lowest for the conforming cantilever 1. The two cantilevers could now be >200, instead of in bedrock, and to mobilize scheme and had not put a price against their constructed more quickly and simultaneously, their shaft friction. This generally led to shorter alternative scheme. only offenng it for negotia· instead of successively. It took the contractor piles in the alternative scheme. For the marine lion in case the group was awarded Phase II. seven months to convince the Highways pile caps we retained the bored piles of the However in February 1989 the contract for Department that this revised method was fea­ conforming scheme. The alternative scheme Phase Ill was awarded to Dragages at a value sible and to have the use of one launching girder represented a substantial saving tn quantities of HK$280M with completion in July 1991 . accepted. compared to the conforming scheme; concrete Arups' Hong Kong office was again asked to Appearance was reduced by 15%, reinforcement by 50%, carry out the detailed design for the contractor, Because the structures were to be imposed on and prestress by 10% . and Tony Gee Chappelle HK Ltd was appointed a compact urban area, their appearance was The contract for Phase II contained, apart from to act as the independent checking engineer for important. The complete scheme was subJect to the viaduct. substantial other works: both Phases II and Ill. the approval of ACABAS, which has a role (1) extensive ground level road works Detailed design: Phases II and Ill similar to that of the Royal Fine Art Comrn1ss1on (2) 1.5km of trunk sewer diversion The Phase II contract was the largest ever to in the UK. A good deal of time and effort was (3) 0.5km of new seawall with reclamation in the have been awarded by the Hong Kong High· spent on purely aesthetic aspects such as the Kowloon Typhoon Shelter ways Department, and it was the first time they locations and shapes of the columns, the ap­ (4) a new Kowloon Passenger Ferry pier. had accepted an alternative design for a maior pearance of the structure when seen from scheme. It was also the first ltme that precast below, the positioning of deck drainage pipes Arups carried out alternative designs for the segmental construction was to be used, not only where these had to be unavoidably attached to trunk sewer and for the foundations and the in Hong Kong, but in Southeast Asia. the underside of the deck. and the shape of the main deck of the Passenger Ferry Pier. Detailed design, based on 885400 and the HK parapets. The tender Civil Engineering Manual, started March 1989. Tenders were submitted in December 1988, Foundations with Dragages corning lowest at HK$770M for The award of Phase Ill had important conse­ Bored piles were used for the marine pile caps their alternative scheme. For the conforming quences for programme and design. Phases II and barrettes for the land-based ones. To prove scheme, the lowest bid of HK$835M was also and Ill had been awarded as two separate our design cntena for shaft-friction and end­ submitted by Dragages. They were awarded contracts and required therefore a launching beanng capacity for barrettes not founded on the contract in January 1989 on the basis of the girder each; the contractor however wanted for bedrock, the contractor carried out a successful obvious reasons to use the same girder for both. alternative scheme and Arups' Hong Kong test on a barrette section 1.0m x 2.0m, of 40m office was commissioned to carry out the The alternative scheme and the contractor's length. Other foundation design criteria differing detailed design for the contractor. Completion initial erection programme for the 1500 seg­ from the conforming scheme were that, for was in July 1991 . ments of Phase II were based on a four-day barrettes, reinforcement would be provided in the top 24m below the pile cap, and for bored Phase Ill tender design erection cycle for a pair of parallel cantilevers, equivalent to 40rn length of dual carriageway. piles, from the pile cap to a level 24rn below the The conforming scheme seabed; below this depth we would reinforce the tender documents for Phase Ill were issued In order to fit the erection of Phase Ill, requiring 700 segments, into the programme. using only only if tensile stresses were developed in the in November 1988 by the Highways Depart· cross·section. ment's Kowloon Office. The whole of this 1.4krn one launching girder, the contractor had to long, strongly curved, overland viaduct was accelerate the erection cycle to three days. Fig. A bored pile requires either a permanent or a designed as 1n situ prestressed concrete con· 4 shows the principal steps in the four-day erec­ temporary steel lining; 11 the latter, then a structed span-by-span. The cross-section was a tion cycle of a pair of parallel cantilevers 1 and 2: nominal reinforcement cage is necessary for the single multi·cell box, 20rn wide and 2.25rn • Move girder forward (2) full length of the pile, irrespective of the criteria deep, with span lengths from 26rn·46rn. In addi· • Position pier segments on cantilever 2 (3) stated above, to ensure the integrity of the pile lion. there was a 0.2km long ramp, generically • Move girder sideways and position pier during withdrawal of the lining. part of Phase II, and designed by the Phase II segments on cantilever 1 (4) This adds to the potential saving 1n steel quan­ engineer FFM . The foundations were 1.8rn dia­ • Move girder forward tities if barrettes can be used. Due to our inter­ meter bored piles to bedrock. and construct balanced cantilever 1 (5·7) active soil-pile design it was only in a very few The alternative scheme • Move girder sideways cases that reinforcement had to be provided in Arups carried out an alternative foundation and construct balanced cantilever 2 the lower parts of the barrettes. This led to design using 1.0rn x 2.8m barrettes instead of • Construct 0.2rn wide in situ closing stitch . substantial savings 1n reinforcement.

4. If n a a a ~ 2. cz.··.-ix· 5. a a n w- rr n 3. 6. 0 a a If n

7.

4. Pnnc,pal stages in four-day erecuon cycle of parallel pair of cantilevers o 0

4 Maximum: 9.2m r--- Typical: 6.2m ---.---1 I I Minimum: 5.0m I I 5. Phase II I t-- 3.6 to 4.Sm ----j column top. --- -I.. '""~Q ~ ~f [JJJ1' '"l _)._

Typical: 12. 7m ------i-~~~~~~~~~~~~~~~~- Maximum: 14.7m 1,. Minimum: 7.Bm ------~1----- t- 3.6 to 4.Sm ----j ··- -- ~\~'----_Jr-- -=- __ , r~D J 7. Phase II segments.

The columns The segments The front elevation of the conforming column The geometry had to be fixed very early, to allow support the 450 tonne launching girder during was generally maintained, but the side was time for the contractor's formwork design. the cantilevering of the segments (Fig. 9) . changed to make room for the equipment re­ Casting of the first segment was scheduled in The most critical tasks of the design were to quired to fix the pier segments to the column September 1989, and the manufacturing of the develop the cable profiles and the reinforce­ during the cantilevering. casting cells, seven in all, was to be tendered ment cages for the segments. The contractor's The controlled un-hooking by the launching across the border in The Peoples Republic of production target for the 2200 segments was 16 girder of a segment pair would normally ensure China. months, based on a production cycle of one that the out-of-balance force would be less than Apart from the anchorage rib and a decision to segment per cell per day for the seven casting 20 tonnes; however the fixity and the founda­ have two web thicknesses, 450mm and cells. In order to achieve this rhythm it was tions had to be designed for the extreme case 500mm, in the large segments. only minor imperative that the segment reinforcement of a segment being accidentally dropped. changes were made to the segments as en­ cage, including the cable ducts. was entirely The deck visaged in the alternative tender design. Fig . 7 prefabricated, and that anchorages, inserts. Phase II consisted of 27 individual structures shows typical large and small segments for lifting holes, openings for drainage gullies, etc .. separated by expansion joints. From a design Phase II. Fig . 8 shows the shear keys and the could be installed quickly and without adjust­ point of view we had 18 different bridge decks possible duct positions in the end-face of a small ments to the cage after it had been positioned of varying complexity, from the simple straight segment. The shear keys act to carry the shear in the casting cell . The transversely stressed bridge along the seafront to the tapering and across the joint until the epoxy glue applied to diaphragms of Phase Ill required individual curved bridge at the ramp bifurcations. the end-faces has polymerized, usually after reinforcement drawings at 1: 10 scale. to satisfy about two hours. the contractor that there would be no surprises Phase Ill consisted of 10 four-span bridges. The during production on site. 20m wide deck was. due to land restrictions. Due to their weight the pier segments were split supported at each pier location by a single cen­ in two halves, each 2.1825m long, while the Drawing production tral column. The alternative deck cross-section length 'I' of the intermediate segments in a parti­ Arups produced 1200 drawings for Phases II consisted of two boxes connected through a 1m cular span related to the span length 'L' in the and Ill during the first eight months of the ,n situ stitch, containing the central barrier. At following way: design. In addition to these, a large number of pier locations transverse prestressing was intro­ 3.6< I= (L - 2 x 2.1825 - Gap)/N <4.5 schedules or so-called catalogues were produc­ duced to transfer the web shears to the where N = 7, 8 or 9 and Gap = 0.2m ed, and it was in fact these, rather than the draw­ bearings. There were six different span con­ (the in situ closing stitch at midspan). ings, that the contractor used for the segment production . Each segment had a set of figurations to design. Fig. 6 shows typical cross­ Analysis and design sections along the viaduct. catalogues giving specific information relevant Using the in-house BAILO program a grillage to the production of that segment. The most im­ model for each structure was built up and portant of these catalogues were: loading was applied in the relevant construction stages. Construction loads from the launching (1) Segment, Reinforcement and Form work, girder and other equipment at each stage were containing overall geometry data and bending supplied by the contractor and taken into schedules account. Stresses were checked at each con­ (2) Prestressing, giving anchorage sizes, duct struction stage and at long term after creep sizes, profile data for prefabrication of ducts. and cable support shapes Phase II : Eastern bifurcation redistribution using the PREPAK program. The western bifurcation of Phase II was parti­ (3) Inserts and Openings, listing all the various cularly complex. The cross-section was made hangers. gully openings, access holes, etc., up of four segments, column positions were which might be required in a particular restricted due to interference with the ground segment. level roads, and it was not possible to locate a Over 60 OOO A4-sized sheets/schedules, each column below each segment. To overcome this, with unique information, were produced for the Phase II : Central section solid diaphragms connecting the columns in the segment production. These documents were transverse direction were constructed in situ not certified by the checking engineer as he was and the precast segments attached to these. concerned only with the checking and certifica­ These diaphragms, 3m wide, were designed to tion of the drawings.

Phase II : Western bifurcation =

Phase II : Ramps ~ 00 0 (?- 0 t) ~01) t=, 00000

Phase lfl

6 Typical cross-sections. 8 Phase II segment· shear keys and duct poSltions. 9. Diaphragm at western b1furcat1on.

5 CONSTRUCTION The first of the 300 barrettes was constructed 1n May 1989 (Fig . 10). The seven precasling cells, containing 600 tonnes of fabricated steel with hydraulically-operated shutters, were in­ stalled on site in August 1989, and the 112m long launching girder arrived in September 1989 for assembly and testing on site.

10

Segment production Fig . 11 shows the layout of the precast1ng yard. (7) Rotate and tilt segment 2 to suit horizontal Behind each of the seven casting cells are four and vertical alignment of bridge jigs where the reinforcement cages were pre­ (8) Twist casting cell to suit changing super­ fabricated . Five of the cells produced inter­ elevation of segment 3 1f required. mediate segments and the others pier seg­ ments. The batching plant and the storage area The segments were lilted out of the casting cells for the segments are next to the casting cells. only 11 hours after concrete pouring and without steam curing. Concrete strength at this The most important steps 1n the 24-hour seg­ time was 18Mpa, and after 28 days: 85Mpa. ment construction sequence are: (1) Place reinforcement cage for segment 2 in Early strength was measured non-destructively outer shutter of casting cell against segment 1 using a maturity method based on temperature in counter-mould pos1t1on readings 1ns1de the hardening concrete. The (2) Push 1n inner shutter concrete technology was refined by the con­ (3) Close end of form with stop-end shutter tractor on recent precast works 1n France. (4) Cast segment 2 The first segment was cast, as planned. 1n (5) Remove segment 1 to store, and lift seg­ September 1989, and the production rhythm of ment 2 into counter-mould position one segment per cell per day was reached after (6) Survey segment 2 and revise dimensions of three months. The last of the 2200 segments segment 3 accordingly was cast 1n December 1990.

6 Deck erection The project team This began for Phase II in November 1989. The In jobs of this type where the detailed design first two spans of the western exit ramp were does not begin until after the contract has been erected by crane (Fig . 12), giving access for the let, considerable effort is required to ensure that launching girder onto the bridge (Fig . 13: the design is at least one step ahead of con­ December 1989). The first deck to be erected struction. Credit is due to the Arup staff in Hong by the girder was the bifurcation with the three Kong, particularly the draughting and detailing in situ diaphragms. The girder then moved teams, who worked under great pressure to pro­ towards Phase Ill. The whole of Phase Ill, 1.4km duce the hundreds of drawings and catalogues of dual two-lane carriageway, was erected in which had to be issued on time to satisfy the three months. Fig. 15 shows the temporary extremely tight construction programme. supports required at the single columns of Phase Ill to allow cantilevering of the two lines Conclusion of segments. This project provides an excellent example of Fig. 16 shows a pair of segments being posi­ the benefits which can be gained from co­ tioned. The epoxy glue is applied to their end operation between consulting engineer and faces immediately prior to the installation (Fig . contractor in a design-and-construct relation­ 1 7). The main purpose of the glue is to provide ship. In this case, at the time of tendering, the a watertight joint - particularly critical during consultant, in the role as designer. was able to the grouting of the permanent cable ducts. assure the contractor that his proposals for an alternative method of construction were both Fig. 18 shows the installation of the temporary viable and economical. Later, after the award Dywidag bars during erection: After having of the contract, the consultant expanded his completed Phase Ill in July 1990, the girder preliminary design into detailed design with travelled back onto Phase II and the erection of comprehensive construction drawings and was the viaduct was completed in April 1991 . The available to assist the contractor in fine-tuning contractor could in fact have completed 3-4 his scheme and in dealing with any unforeseen months earlier, but due to contractual restric­ circumstances. tions could not gain access to the eastern end of the site until February 1991 . Route 6 officially It is worth emphasizing that although the con­ opened for traffic on 1 July 1991. tractor's bid was competitive it did not offer a During the erection of Phase II the contractor utilitarian solution: on the contrary, by virtue of achieved an erection speed of 72 segments in his ingenuity, expertise in construction and one week - equivalent to 160m of dual three­ organization he was able to satisfy the client's lane expressway, or 4000m2 of bridge deck in exact requirements with a scheme that was one week. efficient and financially economical.

Credits Client: 19. Phase II columns with new seawall Hong Kong Highways Department on the lett; Kowloon tower blocks in Contractor's designer: the background. Ove .11.rup & Partners Contractors: 20. Nearing completion of Phase Ill, Dragages. Bachy Soletanche JV June on the nght 1s the partially 1990; Photos: completed HACTL air cargo terminal, L.M. Lui another Arup Hong Kong project. Illustrations: 21 . Completed Phase Ill . July 1991 . Ajoy Ghose

7 1. Sua Pan, Soda ash project, showing scope Sua Pan, Botswana of soda ash project. Coli n Dittmer Ernie Hall

Introduction Soda ash (sodium carbonate) is an important material in the glass, metallurgical , and deter· gent industries. The 700M Pula (£190M) project recently completed at Sua Pan in Botswana is 2. The plant across designed to produce about 300 OOO tonnes per the solar ponds. annum, approximately 10/o of world output and enough to make Southern Africa self-sufficient in its production. In addition , some 650 000 tonnes per annum of common salt (sodium chloride) will be produced as a by-product for use in the food , agricultural, and chemical industries. The client. Soda Ash Botswana (Ply) Ltd. (SAS), is jointly owned by the Government of Bots· wana, AECI , and the Anglo American Corpora· lion , and the project represents an important joint venture between the Botswana Govern· ment and Southern African industry, tech· nology, and financing. When in fu ll production, it will generate some P120M per annum in foreign exchange for the reg ion. The plant is located about 180km north-east of Francistown, on a sandy spit of land protruding some 20km into Sua Pan on the north-eastern side of the Makadikgadi Pans complex in north· eastern Botswana. The site is about 8km from Nata, the eastern extremity of another important Arup project, the 300km Nata·Maun road. The process The production of soda ash involves extracting brine from an aquifer below the pan surface. The brine is pumped from a wellfield covering over 1SOkm :! in the northern part of Sua Pan into 20km2 of solar evaporation ponds on the northern side of the spit, where it is concentrated Infrastructure development associated with the A dedicated project team was thus established, and common salt deposited and harvested. The project includes a 170km rail link to Francis· comprising the principal contractor, the Arup remaining liquor is then pumped to the process town, a new 40km road to Dukwe, two 40km team , and a number of client personnel, who plant on the spit for the extraction of soda ash. pipelines, an airport, and a town of 600 houses were all accommodated in a separate project The plant itself covers an area of 65ha and in· together with associated infrastructure. office. The principal contractor's involvement eludes the following: The contract team amounted to nearly 1M man-hours, of wh ich • A 170 tonnes/hour steam plant SAS appointed a principal contractor corn· Arups' involvement represented about prising Uhde (Ply) Ltd. and LTA Process 160 OOO , with staff peaking at around 60. • A C02 recovery system Engineering Ltd. to be responsible for the entire • A 20MW turbo alternator Speclal features of the proJect engineering and management of the project. The remoteness of the site made the work • Carbonation and crystallization vessels The principal contractor in turn appointed Arups logistically complex, especially because of the • A thickener as a third member of their team , to undertake initial lack of infrastructure at the site, the travel • Calcining and compacting units the design, documentation and site monitoring distances involved, limited construction capa· for all the civil, structural, building, foundation city with in the buoyant Botswana construction • Salt washing and milling units engineering, and infrastructural aspects. • Coal and product handling industry, and controls governing the processing and storage facilities Uhde, who undertook the overall project of work permits for expatriate staff. In addition, management, also appointed Arups' sub· the programme demanded that engineering • A railway marshalling yard sidiary, Capital Projects Planning Services (Ply) and construction of the entire project be corn· • Ancillary buildings, i. e. stores, offices, Ltd. (CPPS). to supply the computer-based pleted with in 2 V2 years of the principal con· maintenance facilities. project control systems for the whole scheme. tractor's appointment.

70days' Wellfleld Solar pans brine storage i i ------, -u ~ - =1 '------' t.:::___:J

2

4 6 Aacycle~ oo 1. Washing and milling 1 2. Railway marshalling yard [] 0 3. Coal handling 4. Turbo alternator ~~·~l 5. Steam plant Dense Bitterns 6. C0 plant to disposal 2 soda ash C02rec':!!!'!.,~ 7. Carbonization -~ and crystallization I 8. Calciner 100m 200m Electrical L_Boilers }-, Coal o 9. Thickener power E 10. Ancillary buildings 3. Process flow diagram. 4. Plant layout.

8 Arups' Involvement: overview Geotechnical and foundation engineering • All geotechnical investigation of the plant site, solar ponds and new l..i ' ~ _. • 'a,A.:;.- I town, together with detailed foundation .__ . . . . .~.,) ...... ~.:=--· .,.. ~, design . ·-~ ~~ . • All geotechnical investigation and materials assessment for construction of the plant roads, airport runway, and new road to Dukwe • Geotechnical investigation and materials assessment for establishing a quarry to supply aggregates for construction. The new quarry was, in the end, not established. owing to favourable rates being negotiated with existing quarries in Francistown. • Geotechnical investigation and foundation recommendations for all houses and facilities at Sowa Town. Civil engineering and infrastructure Plant infrastructure • 65ha of terracing and stormwater drainage • 6km of plant roads • 4km of sewerage reticulation • ?km of railtrack in exchange yard Wei/field and solar ponds • Earthwork platforms for wells and electrical substations in wellfield • 60km of earthwork berms around solar ponds • Weirs, pumpstations, and electrical 5. The solar ponds: substations for solar ponds the plant is barely visible in the distance. External infrastructure 6. Solar pond station under construction. • Airport runway • Upgrading existing gravel road to Dukwe for construction traffic The project's unique features related particu­ • New 40km road to Dukwe larly to construction environment, materials, and geology. Building the wellfield and solar ponds, • Two 40km water pipelines for example, involved operating and conveying • 32m diameter, SM litre capacity equipment over large distances on the pan - concrete reservoir still under water at the commencement of the • Sewage treatment works, and project, and in which vehicles often got bogged water and sewage pumping stations down. Special corrosion problems arising from the aggressive conditions had to be dealt with Structure and buildings and available materials used to the best advan­ Plant structures tage, as in construction of the solar pond bund • 30 000m3 of concrete foundations walls and the new Dukwe road . and structures Arups identified these key strategic issues at the • 2500 tonnes of steel plant outset, and proposed and implemented solu­ structures tions to the infrastructural problems while other major process and mechanical engineering Terrace level Ancillary plant buildings 2 issues were still being resolved . In this way, • 1O 500m of administration early and efficient infrastructure construction buildings, workshops, stores, could proceed, thereby enabling critical early substations, and other ancillary plant programme dates for items like the access road, buildings, including HVAC design Nominal 630mm diameter water supply, solar pond bund walls, and piled e::, grouted annulus placed between foundations to be achieved. This fast-track E permanent casing and 650mm Sowa Town i: approach necessitated accommodating fre­ OD temporary casing extracted • Foundations for 600 houses I after completion of pile shaft quent changes to plant and vendor data as the E concreting. 0 • Shopping centre, school, telephone design developed. ..; exchange, social club, and community 325mm diameter. 0.6mm thick Key Arup responslbllltles Armco superllght permanent centre. casing coated with 0.2mm thick Geotechnical and foundation engineering epoxy tar. Permanent casing On-site monitoring of construction The spit of land on which the plant is located over full shaft length. From the start of construction Arups' consists of sandy lacustrine deposits up to 5m resident site staff, established as part 175mm diameter reinforcement th ick overlying the pan deposits. These are soft cage comprising six Y12 vertical of the principal contractor's con­ silts and sands with cemented horizons. to bars over full length of pile shaft. struction management team , monitored bedrock at 40m depth. The deposits are unable construction of the works in relation to to support major loads without large settle­ 410mm diameter thick wall. the specifications. ments, and consequently heavy loads and Franki medium tube with settlement-sensitive structures had to be sup­ potential 85mm voided annulus Project management between temporary Frankl tube ported on piles. Because of the depth to bed­ and permanent liner. information systems rock, advantage was taken of a concretionary CPPS provided the pri ncipal horizon up to 18m below surface, on which contractor with the computer-based driven cast in situ piles were founded with information systems for time, cost, expanded bases to reduce contact pressures. procurement, and document control The adequacy of th is pile type was confirmed for the entire project, as well as staff by trial testing . The piling was complicated by Piles founded on silcrete horizon and hardware lo implement the aggressive ground conditions which necessi­ Pile working load capacity • 750 kN systems for the full duration of design, tated lining with a permanent bitumen-coated 7. Pile detail at plant area. construction, and commissioning. steel sheath. 9 The solutions adopted varied, depending on 8. 40m diameter concrete thickener. whether structures are permanently below or 9. Crystallizauon vessels. above the water table, or in the most aggressive intermediate zone. Generally the solution in­ 10. Impact rolling of plant terrace. volved a combination of good quality dense 11. 16 500m2 clear span soda ash store. concrete with high cement content, the use of 12. Calciner. slagment, cover to reinforcement of up to 75mm 13. F1ltrat1 on and compaction building. and bitumen coating of vulnerable surfaces located in the zone below ground level and the 14. Cooling water pipe trench. lowest water table. 15. Soda ash rail loading facility. Civil infrastructure 16. Soda ash bagging and loading facility. Early contracts were awarded for upgrading the 17. A house in Sowa Town . 10 40km access road from a point near Dukwe on the main road from Francistown to Nata. for the For initial improvement of the founding condi­ two 40km pipelines along this road (one for were constructed with the available pan tions the entire plant area, measuring about potable water and the other for brackish), and materials, and also serve as access roads to 1.1km x 0.6km, was levelled and treated with an for the surfaced airstrip. The upgraded calcrete weirs , pumpstations, and other equipment on impact roller. This produced reasonable but access road was used to carry heavy traffic the pan. variable compaction of the collapsing sands during the construction phase. Towards the end Tests had been conducted by others during an down to about 2m depth. of the project, the final surfaced access road earlier pilot project to establish permeability and was built, a two-lane facility using local calcrete other parameters, and to establish a proposed In order to minimize costs. light buildings and in the construction layers with a double-seal sur­ structures not sensitive to settlement were form of construction. These concepts had to be facing . Shoulders were also sealed. Over the developed into a workable solution. and pre­ founded on individual earth rafts constructed by first 1Okm from the plant, particular attention removing about 2.5m of potentially collapsing contract test section was let to prove the pro­ was paid to design and construction tech­ posed method of construction. material and replacing it in compacted layers. niques, including a bitumen membrane be­ With the water table near the pan surface. the Advantage was taken of the early construction tween the sub-base and base courses. in order to minimize the likelihood of surface blistering procedure involved excavating pan material of three 1Orn diameter, 1Orn high water tanks to adjacent to the proposed bund wall , and measure settlements with different earth raft due to salts migrating upwards from the groundwater. spreading it along the line of the wall. The opera­ preparations. The small settlements measured tion was programmed to allow as much drying under these tanks confirmed the performance The 170km railway link from Francistown, which as possible of the soil to take place to improve of the sands under relatively light loads after supplies coal for the boiler and conveys the the compaction potential, although even then compaction, and enabled soil parameters to be product to the main rail network at Francistown, the material had to be compacted at well above calibrated for prediction of settlements under was designed by others for Botswana Railways. optimum moisture content. It was nevertheless other structures. Subsequent design and con­ Arups were responsible for the railway ex­ demonstrated that with suitably chosen equip­ struction of elements of the plant founded on soil change yard at the plant, including coal off­ ment, adequate compaction could be achieved rafts confirmed these assumptions. loading and handling facilities, bulk and bag along the bund walls within an acceptable con­ Durability of concrete structures loading facilities for the salt and soda ash . and struction programme. The presence of chlorides and sulphates in the rail wagon weighbridges. It was recognized that certain leakage would pan deposits necessitated careful assessment Solar evaporation ponds take place through the floor of the ponds and of the associated aggressive attack on the con­ Establishing the layout for these involved de­ through the walls. These were measured in the crete. Academic advice was sought, and the tailed interaction between the civil engineers pilot project and allowed for in the wellfield and resulting report reviewed by Arup Research & and process consultants. The 60km of earth­ solar pond design. With time, a salt floor forms Development in London. work bund walls around the 20km2 of ponds across the salt crystallization ponds which , 10 together with algae deposits, reduces leakage which is between 4.Sm and 7m above ground town's road and services infrastructure. Arups' and possible damage to the bund walls through level. The thickener was then lined with a flexible work in the Town includes the following: wave action. membrane to accommodate the corrosive salts • Advice on structural and electrical aspects for Brine collection system in the contained liquid and to provide flexibility the houses The brine wells. pumps, and electrical sub­ to accommodate settlement of the floor. Flexi­ • Geotechnical advice relating to all founda­ stations which are situated in the wellfield some bility has been built into items connecting into tions - which are on collapsing sands 20km from the plant have been constructed on the thickener to allow for up to SOmm of settle­ • Infrastructure, civil, and structural design of earthwork platforms to raise them above ment. Measurements of settlements on site have the shopping centre, school, telephone ex­ possible floodwaters in the pan. These earth­ confirmed the design parameters adopted and change, social club, and community centre the soundness of the solution. work platforms were constructed in a similar • Design of 32m diameter, SM litre, reinforced manner to the solar pond berms, by excavating Dense soda ash store concrete reservoir and pumping station. adjacent pan material and compacting it in This major building is 330m long, SOm wide, Concluslon layers after allowing time for drying. and 20m high to the roof apex. it accom­ The principal contractor was appointed in Special structures modates conveyors and sets of rail tracks down October 1988, when the basic process engi­ There are a multitude of concrete and steel each side, on which the slackers and reclaimer neering for the project commenced; an earlier structures in the plant, ranging from bases sup­ run. Between these tracks, a heap of soda ash pilot scheme had been constructed on a smaller porting individual plant items to pipe racks and up to 12m high at the apex is accommodated. scale to evaluate the wellfield, solar ponds, and major structures and buildings. The structural It was recognized that piling under the rail process. Design and construction of the entire design. therefore, needed close interaction with supports along each side of the building to deal project was completed in the stipulated 2V2 the process, mechanical, and electrical de­ with settlements would be extremely costly. years, with the first soda ash coming out of the signers, so as to produce reliable civil and Nevertheless, the stacker and reclaimer rails plant in March 1991 . At the peak of construction structural information to meet urgent construc­ had to be adequately supported to ensure activity, there were more than 2000 workers tion requirements. within a dynamic design minimal differential settlements. Careful analysis employed at this remote site - a logistical environment. Two structures deserve special and design of reinforced concrete ground problem which necessitated providing exten­ comment: beams on the elastic subgrade showed that sive accommodation and catering facilities on Th ickener differential deflections could be contained within site, and laying on road and air transport. The 40m diameter thickener had, for process acceptable limits. In terms of scale, scope of involvement, and reasons, to be some Sm above natural ground The building is therefore founded entirely on ability to contribute to the overall end result, the level; below its floor, access tunnels connect to spread footings and strip beams. The steel Botswana soda ash project has represented an the central extract pump chamber. A number structure is divided into four sections along its important milestone in Arups' participation in of alternative forms of construction were investi­ length to allow for longitudinal temperature this kind of work. gated. Elevated piled structures in either con­ movements; the tubular steel portals at 1Orn Credits crete or steel were considered but would have centres are designed as three-pinned arches. Client. 2 been costly. Instead, the structure was founded and provide a clear span area of 16 SOOm • Soda Ash Botswana (Ply) Ltd. on an excavated and recompacted soil raft The building and stacker/reclaimer system was Pnncipal contractor: and designed to accommodate predicted chosen as more cost-effective than conventional Uhde (Ply) Ltd./LTA Process Engineenng Ltd. settlements. concrete silos and conveyors. Civil, structural, bwldmg, foundation, The reinforced concrete drum is supported on Sowa Town and infrastructure engineers: Ove Arup a spread footing at just below terrace level. This provides over 600 houses for workers at Photos: Foundation preparation involved excavating the plant, together with other facilities and 1: Ove Arup; 2, 5, 9: Dave Norman; and recompacting material down to 2.Sm below amenities. The houses range from high to low­ 6. 10. 14: Ric Bennett; 8. 11 , 15. 16: Cohn Dittmer; ground level. The walls of the structure were cost and are being provided by the Botswana 12. 13, 17: Cliff McMillan. designed to allow earth fill to be compacted Housing Corporation for rental by SAB. The Illustrations internally up to the sloping floor of the thickener, former appointed its own consultants for the 1, 7: Emoke Baroni; 3,4: Fred English 11 Communications and Information Technology Sanctuary Buildings 10 years communicating Toyota lain MacCall Ove Arup & Partners started to develop communications as a specialist Emre Serpen Sanctuary Buildings, a 12-storey consultancy service 1n 1981 . Since then the group has grown to serve many The new Toyota motor manufacturing office block near Westminster Abbey, clients on widely differing proiects. Those described here are of two kinds: plant is being established at is the new head office of the Depart­ ones on which communications is the sole service provided by Arups and Burnaston near Derby. When fully ment of Education and Science those where it 1s one amongst many. operational, it will have a total annual (DES) for around 1200 staff, The last 10 years have seen an increasing awareness of the impact production capacity of 100 OOO cars completed in December 1991 . communications and information technology (IT) are having on buildings. p.a. Shimizu (UK) were responsible Back in October 1988, the DES Few proiects or clients are unaffected by changes 1n the technology which for liaison with Toyota Motor invited Arups' Communications & IT allows people to talk, exchange text, or transmit pictures remotely , with Company (fMC ) and for design and Group to review the proposed increasing ease. To the problem of designing a building to accommodate construction co-ordination. Arups' facilities for the communications infra­ many generations of IT system 1s added the question: what kinds of system Communications and IT Group. as structure in Sanctuary Buildings. As should be provided? The Communications and IT Group. located in the part of a large multi-discipli nary a result, extensive changes were Industrial Engineering division, sets out to help solve the first and to answer design team , including staff from proposed, which had a significant the second. Industrial Engineering, Birmingham impact on the structure and services. office, and other parts of the fi rm . Recommendations were implemented, the main link between Darlington been provided into the Government designed the communications and IT including: and Sanctuary Buildings. Telephone Network (GTN) run by the systems that are integral with the plant facilities. (1) Dual entry points into the For the smaller amount of data traffic Central Computing and Telecom­ building for public network services between Elizabeth House and munications Agency (CCTA). In the From August 1989 the Group (2) Larger central communications Sanctuary Buildings, telephone data event of a failure on the dedicated assisted Shimizu with a series of and computing rooms with special sets were used to carry data via the link, voice calls are automatically investigations including advice on the services requirements inter-PABX links. rerouted via the GTN. to provide a legal and regulatory aspects of wide backup facility. This also supports area communications in UK. avail­ (3) Provision for sub-equipment The i11tegration of voice, data and rooms which act as flexibility nodes data communications. ability of equipment and systems, image communications on a single capabilities of suppliers, and tech­ and house the communications and high speed link introduced the risk of Arups provided significant input to IT equipment serving each floor the design process and to the co­ nical feasibility of specific communi­ the two sites being cut off from each cations requirements. A plantwide (4) Various methods to provide IT other in the event of a single fault. ordination of communicati ons and services to desks equipment suppliers at all three of communication strategy was Strategies were evolved to reduce developed. which included: (5) An uninterruptible power supply this risk. The multiplexing equipment the DES major sites, and introduced for IT equipment. a new integrated, wide area network. ~) A broadband system to provide chosen includes fu ll redundancy and the networking medium for factory Approximately 850 PC workstations diagnostics so that any failure in this Credit automation, building management, from their old premises, Elizabeth equipment is unlikely to disrupt Client: and office automation applications House, near Waterloo Station, and communications; digital links have Department of Education and Science (ii) The voice services exchange others from smaller offices, were (PABX). which also interfaces to relocated and networked at Sanctuary Toyota's new engine plant at Buildings. Due to existing investment, Shotton, and to other offices and the most cost-effective networking plants in Japan and Europe. The solution was a structured Ethernet voice cabli ng system is compliant wiring scheme based upon thick-wire with Integrated Services Digital backbones with horizontal thin-wire Network (ISDN) standards and when segments. This provided around fully expanded will comprise 1000 1800 outlets allowing for projected voice outlets. future expansion. (iii) A satellite master antenna tele­ To allow for the predicted data traffic vision system (SMATV), able to and to give resilience, four bridged receive Japanese programmes backbones were used. Multiport broadcast via European satellites. repeaters, with the ability to include local bridges separating individual user groups from the backbones. were installed in each of the 22 sub­ equipment rooms. The equipment used had integrated network management facilities so that faults could be diagnosed from a central location. 1. Education Secretary using video conference facility. (Photo: British Telecom) Remote bridging facilities allow electronic mail services to operate 2. DES communications network. (Illustration: Fred English) between Elizabeth House and Sanctuary Buildings as well as providing access to the mainframe in the Northern HO at Darlington. The Department's voice network was designed to allow PABX management functions including call logging to be controlled from the Darlington office. The network also allows central operator working so that all calls, including those made to the London office, can be answered by the telephonists in Darlington. The Department operated a video conferencing link between Elizabeth House and Darlington; Arups High speed designed both the new studio and digital access the communications link to Sanctuary Medium-speed Buildings. The voice and data wide digital link area networks were integrated using Analogue lines the drop and insert multiplexers for 12 The use of broadband technology 550 taps on demand without LFB tower; desk study was initially developed for cable necessitating further deS1gn modifi· for alternatives television. The frequency spectrum is cations. There are 15km of 20mm divided into 6MHz channels, enabli ng cable. over 20 trunk and 60 Bill Southwood a number of services to run simul­ distribution amplifiers , and a com­ Like all emergency services, the taneously on the same cable. Broad· prehensive status monitoring system. London Fire Brigade (LFB) depends band networks are capable of In order to enhance the reliability of heavily on mobile radio to control its supporting a wide variety of com­ the network, a dual trunk system is operations. Each fire engine and munications protocols, including provided where alternate rows of ancillary vehicle must be in contact manufacturing automation protocol taps are led from each trunk cable at all times by a radio system which (MAP). which enable different and all trunk amplifiers are provided is reliable, robust and available. with active standby modules. computer systems to communicate The capital is served by base with each other. The Toyota (UK) The Group also had a Significant stations on Hampstead Heath plus broadband system 1s designed to input in the tender process. both three others around the edge of the MAP standards and is based on a with interviews and technical Greater London area. The Hampstead 'distri buted star' solution, where appraisal, and this technical co­ site had been the subject of amplifiers and other active equipment ordination role continued throughout numerous planning appeals, and the are located at pre-determined 'hub' the contract. The installation of temporary tower at Queen Mary's locations. thus easing system communications and IT systems is Hospital therefore had a limited life. signals from other base stations. Few maintenance. complete, and commissioning is The London Fire and Civil Defence could accommodate the number and A structured grid system, covering expected in 1992. Authority (LFCDA) called tenders for range of antennae needed by the production, office and utility areas, the design of a 63m high tower on a fire service, nor the radio equipment was adopted; the scheme. wh ich Credit new site, at that stage undefined. on itself. Availability of reliable power initially comprises 400 taps (access Client. the Heath. Ove Arup & Partners was a key consideration, as was points). was designed to expand to Sh1m1zu (UK) Ltd. were successful, with the support of access for maintenance. Arup Associates. in being appointed There was an additional complication: for this project. the international body responsible for At the same time, the Communications controlling the radio spectrum, in and IT Group proposed that the Fire trying to meet the burgeoning Brigade should look into alternatives demand for mobile services, had to Hampstead as the site for the squeezed the frequencies available tower, because any planned to the LFCDA. Whereas previously a structure in the area was likely to be slightly inferior site might have opposed. An independent study provided acceptable service. the could therefore have two outcomes, narrower frequency bands meant both beneficial: it might identify an that any degradation would be alternative site less likely to result in reflected in poorer service. The study a public enquiry; on the other hand, therefore concluded that, with the if it concluded that there was no technologies currently in use, no practical alternative, this would be suitable alternative existed. useful to the Authority in arguing the Technological change case for the new tower. The last 10 years saw major changes The need for Hampstead in the technology of mobile radio: Hampstead Heath is particularly well­ cellular had boomed, satellite mobile located for a radio base station services such as the International serving Greater London. It is central, Maritime Satellite (INMARSAT) system 3. Toyota broadband installation. (Photo: Ove Arup & Partners) with clear lines of sight through 360° had matured, and a new technique for a considerable distance. It is high known as trunked mobile radio had 4. The Toyota factory, October 1991. (Photo: Jefferson Air Photo) enough to clear obstacles. but not been developed to give better use of so high that it would interfere with the available radio spectrum. other radio services using the same The special needs of the Fire frequencies in the UK and indeed Brigade included all units being in elsewhere in Europe. The Fire communication with the base and Brigade's other stations had been each other at all times. Additionally, selected to fill in areas not well­ no situation where traffic from other covered by Hampstead but which sources might interfere with emer­ could not, by themselves, cover gency calls could be tolerated. Central London. These two factors effectively ruled The study therefore concentrated on out terrestrial radio technology - two aspects: the availability of a site satellite service offered the tempting which could replace Hampstead, alternative of eliminating any radio and the likelihood that emerging base station on the ground. However, technologies might radically change with a satellite 'base station' located the communications needs of the 36 OOOkm above the equator, signals Fire Service. are very weak, and need a clear line of sight to the vehicle. This does not Alternative sites As one would expect, given the exist at street level in the city, so sensitivity of the Hampstead Heath satellite was eliminated as well. area, the fire service had investigated The desk study therefore provided many possible sites. These had conclusive support to the case for a included the Telecom Tower, the new station on Hampstead Heath. In National Westminster building, the event, the Arup design for a site Goldfinger's Trellick tower near near the St. Columba Hospital Westway, Alexandra Palace. and gained planning approval without the many others. Each had drawbacks: need for a public enquiry, and the in many cases the height was new 63m guyed mast was erected unsuitable, too high being as bad as during October 1991 . not high enough. Sight-lines were not Credit generally as good as from the Heath, Client which itself forms an obstruction to London Fire and Civil Defence Authonty

13 Communications and Information Technology (continued) Hewlett-Packard, countries. In 1988, HP were in the fibre optic cables to give resilience in Cellnet, Slough process of changing their internal the face of future developments in Bracknell communications from the point·to­ communications, particularly with the Jim Read Peter Keogh point serial RS232 system, running at up-coming Fibre Distributed Data Cellular radio was one of the corn· munications success stories of the Hewlett-Packard are famous for speeds up to 9600 bits/sec .. to the Interface protocol (FOOi). 1980s. Launched in 1985 by two computers. test instruments and . high-speed bus IEEE 802.3 system The site was essentially a campus companies - Cellnet and Racal among the engineering fraternity, for (commonly referred to as Ethernet) development and a system of Vodafone - its growth outstripped calculators that refuse to die (long running at 10M bits/sec. These new external ducts had to be devised to the most optimistic predictions. In after HP have brought out devices networks now allow for sophisticated serve the five buildings. Factors like which are smaller. faster. cheaper. management where fault conditions 1989 it became clear to Cellnet that cable pulling lengths, bend radii , a new headquarters was needed, better. etc.). They had several offices at remote offices like Manchester can etc .. had to be considered; significant around Berkshire and wanted to be identified. Faulty ports or equip· and they chose a building opposite costs were involved and it was worth Slough British Rail Station. Ove Arup consolidate into a new UK HQ, ment can be disconnected from the spending time to get it right. The & Partners were appointed to design aspiring to a 'new standard ' in network while they await the arrival final scheme was an arrangement building design. HP acquired a large of support staff to swop out or amend and implement communications and which allowed for the ring circuit IT systems within the building. piece of land at Amen Corner near the defective parts. The scheme for implementation of FOOi but was also Bracknell and commenced work in the data cabling needed to accom· sensitive to the needs of two only of Cellnet and cellular radio 1988 for the fi rst two of the five modate both these networking the buildings to be masters for Celine! is jointly owned in a 60/40 buildings included in the master systems. communications, each serving a split by British Telecom and plan. Ove Arup & Partners' The cabling for both voice and data number of other buildings. In 1990, Securicor respectively. Its network Manchester office were responsible was based on AT&T Premises Dis· the second building of the master covers 97% of the UK population for the building services design, and tribuhon Scheme (PDS as it was plan was completed, along with the from the Shetlands and Orkneys to the Communications and IT Group then, now referred to as SYSTIMAX). interconnecting external and internal the Channel Islands. Radio base invited to assist with the project. configured into a structured wiring copper and fibre optic cable. forming stations provide coverage in both scheme. On the floors. radial cables an integrated network. urban and rural areas. the UK being The building was to be the maior divided into a large number of computer and communications node out from a central equipment room The buildings have now been in use on each level ran to grid outlet 'cells'. In urban areas cells are as for the UK. About 1200 staff, in a for some time and the systems have close together as 500m, whilst in largely open plan environment, points (GOP) under the raised floor. stood the test of time. The client has Service to the desks was via a drop sparsely populated regions the needed to have a highly adaptable been able to reduce his 'churn' spacing may be as large as 20km. communications infrastructure to cater cable connecting GOP to desk costs dramatically; the costs for surface, passing through the raised By early 1991 there were over 750 for the many changes to depart· communication installation when Celine! cells in the UK. mental requirements and locations. floor via a grometted opening. desks move has been reduced by as HP responds flexibly to industry Compared with the traditional floor approximately a factor of 10. Whole Frequencies in the 900MHz band demands. box. this proved to be a remarkably departments can now be relocated are re-used over and over again as The wide area network and internal cost-effective method of physical within a day with continuity of service the cellular telephone automatically communications for the company cable management. at under 10% of assured. A successful design, selects the base station with the had been based on Case OCX comparable cost. implemented. strongest signal. Each base station is linked to an electronic mobile systems giving access to data files The building data backbone cabling Credit and users across the UK. to the was thick wire 802.3 cabling exchange (EMX) which controls the Client: call, and arranges for the 'hand-off' USA, and to some European enhanced by 125/62.5µ multimode Hewlett-Packard Ltd from one cell to the next as the mobile moves around within the service area. Control of the total network depends critically on reliable links between the EMXs. Faced with an explosive demand for 6. Patching in Hewlett-Packard's its services. especially in major cities sub-equipment room . and motorway routes. Celine! (Photo: Ove Arup & Partners) embarked on a major expansion programme in the late 1980s. This 7. Hewlett-Packard office area resulted in a threefold increase in (Photo Peter Mackinven) capacity from 10 OOO simultaneous telephone conversations in January 1990 to 30 OOO in March 1991 . Such a growth in demand placed the organization under great pressure. and required much innovation to find novel ways to use the radio frequen· c1es available. One result was the need for a new headquarters build· ing to house not only the organizati on, but also a new Network Management Centre (NMC). This accommodates the facilities to monitor the entire UK network for traffic demands, system performance and fault conditions. enabling any required corrective aclton to be taken 1mmed1ately, at remote locations, often before service to the customer 1s affected. Slough building As a communications organization itself, Celine! needed its own to be of the highest quality. The building had therefore to be fitted out both with links to their other sites and a flexible internal infrastructure to cope with rapid changes. Also the project needed to be completed very quickly, with the first groups moving in within four months of our being appointed.

14 The first task was to produce an out­ data networking equipment and line communications strategy. Each software by Datarange. Work operating group of Cellnet was commenced on site early in 1990, considered, and staff from technician and the groups moved in between to managing director interviewed. March and June that year. The 9. Cabling to the desk, Hambros Bank. (Illustration: Nigel Whale) This established the communications systems provided have been 10. Hambros dealing area. (Photo: Peter Mackinven) needs and priorities for the building, subjected to many generations of with one need emerging clearly: moves and changes since then, and maximum adaptability. Having provide Cellnet with a facility which started work in November 1989, the matches the dynamism of the report was presented to Cellnet organization itself. management before Christmas, and Credit formed the basis for the design and Client: implementation stages. Cellnet Ltd. Communications systems The communications design had to accommodate changes expected Hambros Bank right up to the date for the move. An Sam Shemie infrastructure of cabling was provided which would allow almost any Hambros is one of the large City grouping of departments and layout merchant banks, with other offices in of furniture to be adopted. The PABX Pall Mall and Brentwood, and a (telephone system) had to allow number of subsidiary companies direct dialling inwards (DOI) and the offering a wide range of financial ability to log costs and traffic statistics. services to clients. Having grown so rapidly, Cellnet had Hambros' new building at 41 Tower a wide range of computer systems, Hill is located in a prestigious One of our first tasks was to assess Hambros made their own dealing models, and uses; some were net­ position overlooking the Tower of and define the impact of communica­ desks in-house - a cost-effective, worked together, others connected London and Tower Bridge. It tions and IT on the space and tailor-made product. to mainframes which would not consists of nine floors plus basement, services requirements in the building. 2 Hambros had a range of mainframe move, and the remainder had to be each approximately 2500m with a The requirements for computer 2 computers acquired over the years replaced. Another objective was 180m internal atrium built into the rooms and subequipment rooms, by the various line divisions. A therefore to develop a strategy to centre from the third floor upwards. risers, vertical and horizontal tray modular system was the basis for allow all machines in the new The project was carried out in distribution were defined; two distribution of data cabling, enabling building to work with one another conjunction with Arups' Building subequipment rooms per floor were the Bank to connect to a variety of and with remote computers. This Engineering Group who undertook required to house the patching host machines. It also enables them included systems as diverse as the services design. frames and the data networking hard­ to use the same system for local billing, personnel and management ware serving the users on that floor. When Hambros decided to move, area networks like Ethernet and information. they used this opportunity to review Given the frequent internal moves Token Ring. As a communications carrier, Cellnet their communications, dealing and IT and changes within the Bank, needs to cater for a large number of systems. Voice communications Hambros needed a highly adaptable The migration of staff into the new general enquiries and any complaints include a networked telephone system. Voice and data distribution building had to be planned in great that arise. An efficient means had to system as the backbone for the was based on a modular subfloor detail, with most communications be found for handling such calls. An Bank's external communications. The grid system with outlets terminated and dealing systems commissioned \ Automatic Call Distribution (ACD) dealers have a dealerphone system, on the slab. Drop cables were used prior to moving in. Due to the system was provided to allow a which provides them with direct to deliver the services from the sub­ complexity of these, the main staff flexible approach with the shortest communications channels to other floor system directly to the furniture move had to take place during the response time to these calls. Finally City institutions, as well as an via 125mm grommets. Use of floor 1988 August Bank Holiday. Arups' the communications for the NMC intercom system for their own open boxes was limited, resulting, as on input to the planning and control of had to be integrated with the voice channel voice communications. other projects, in significant cost the related information made a and data communications for the rest Each dealer position can receive a savings while maintaining optimum significant contribution to the of the building. vast range of fi nancial data routed flexibility. successful move to the new building. On day one, all systems were Implementation via a complex switching system, The dealer room had similar require­ thereby providing a comprehensive reported fully in action and business Tenders were called and contracts ments; provision was made for 210 continued, uninterrupted. placed with British Telecom for the range of formatted data with dealer desks, with all cables telephone system and network optimized access times. The system terminating on a module fixed to the Credit services. Voice and data cabl ing was also provides access to in-house raised floor within the desk housing Client: provided by VDU Installations, with computing facilities. unit. It is interesting to note that Hambros Bank Ltd. 15 Introduction WMDC and WYWMJC separately to Arups' long-standing involvement with Wei beck: ensure that, irrespective of the basic the Welbeck Reclamation Landfill economic viability of the schemes, Project at Wakefield, West Yorkshire, economics and finance each had the resources necessary to started with a study by Arup Trans­ finance the Project. portation for the DoE into designing Jim Nyhan Jonathan Mitchell ResuHs an evaluative framework to improve Both schemes were found to provide disposal methods for colliery spoil in D Meadow pasture void waste space at costs lower than 1984. Welbeck was one of several current market rates and to generate case studies in the three-year • Woodland 1 reasonable economic rates of return . investigation ; subsequent Arup work • Reedbeds t Using a 7% discount rate, it was assessed the environmental N found that the incremental £15M + im plications of alternative rail off­ cost of the full scheme (mainly due to loading points. the diversion of the River Calder), was Evolutlon of the Project more than offset by the income The Welbeck site, some 325ha at the associated with the increased void outskirts of the town, had been space made possible by higher spoil subject to sporadic but extensive intake from Selby. The unit cost of sand and gravel working, deep mine providing each m3 of waste space, and open cast coal extraction, and the 'implicit cost of waste'. was found the unco-ordinated disposal of both to be about 30% lower for the full colliery spoil and pulverized fuel ash. than the limited scheme. The In the mid-1980s, Wakefield Metro­ economies of scale derived from the politan District Council (WMDC) were larger scheme are apparent in Fig. 3. becoming increasingly concerned The sensitivity of the project to cost about the imbalance between the overruns on the river diversion for the 0 0.5km 1km scale of derelict land in the District, full scheme and the absence of future and the limited funds available for grant receipts was low. Its economic reclamation. The Welbeck site was a viability is sensitive only to the particular concern as it would have availability of spoil material early in absorbed about 10 years' allocation the Project's life to create the waste of the entire District's Derelict Land created. Known as the 'full' scheme, Anticipated costs and phasing of void space. Analysis of the financing Grant to restore. At the same time, as this alternative will have a total capital and operational expenditure requirements demonstrated that both environmental regulations became capacity of about 35Mm3 of spoil and for the Project were obtained from schemes could be financed by each more rigorous, the joint waste waste void space. As well as the WMDC and the West Yorkshire Waste of the public authorities. 3 management authorities in West intake from Sharlston, about 14Mm Management Joint Committee Conclusions Yorkshire were finding that waste void of colliery spoil will be imported from (WYWMJC), who are developing it as The review demonstrated that while space was becoming increasingly Selby onto the Welbeck site, allowing a joint venture. Incomes from waste both are economically viable, and scarce and expensive to provide. the construction of larger waste and colliery spoil intake were meet environmental objectives, the disposal cells to accommodate about estimated by reference to financial full scheme offers economies of scale The Welbeck Project was born from 3 the far-sighted idea that, through 14Mm of waste. Fig. 2 illustrates the arrangements with British Coal which make it the more attractive selling waste void space on the site in differences in both spoil and waste relating to the two coalfields' option, as well as providing both cells within a landform built from spoil void space provided by the two disposing spoil on the site, and by additional security for waste disposal generated by local collieries, it was alternative schemes. accounting for the investment of the and a solution to the spoil disposal possible to finance the restoration of waste management authorities as needs of the Selby colliery. The review An•lysls commensurate returns in the form of the area and return it to public open The land-take for the two alternative clearly demonstrated its superiority. space (Fig. 1). It is an imaginative void space provision for waste. schemes is almost identical, but the Expenditure and income data for both The review was carried out to a local authority response to two major procedural difference is that the demanding schedule. The economic seemingly separate problems; mineral joint venture partners were consoli­ river diversion needs Parliamentary dated to provide a complete cash and financial analysis of the Welbeck workings dereliction, and scarce approval through a Private Bill. As a Project strongly supports the client's facilities for waste and colliery spoil flow projection for the alternative result of Arups' earlier involvement, schemes, and discounted cash flow case, and the value of the work seems disposal. the Project Manager of Welbeck to have been greatly appreciated. 3 techniques then applied to examine Initially, about 7Mm of spoil was to asked Arup Economics & Planning to the fundamental economic viability of Reference be imported from the nearby carry out an economic and financial each scheme. (1) NOYCE, M. The disposal of colliery Sharlston Coalfield to create two review of the proposals, with the aim spoil. The Arup Journal, 22(2), pp.6-7, artificial hills either side of the River of contributing to a viability assess­ Their viability was also examined with Summer 1987. Calder, which bisects the site; these ment for a House of Lords Select reference to the current cost of obtaining waste void space. Credits would enclose 7Mm3 of waste void Committee of the proposed diversion To Client: space. This is now referred to as the of the Calder. The review was to be assess economic efficiency of the full Wakefield Metropolitan District Council 'limited' scheme. When it became completed in close collaboration with scheme, the analysis isolated the Consuhants: clear that the new Selby Coalfield, the client, WMDC, and their expert extra expenditure and income Arup Economics & Planning resulting from the provision of its 25km away, would be generating an witness, Professor Anthony Neuberger 3 /1/ustrations: unexpected 1Mm3 of spoil a year, the of the London Business School. The additional, or 'incremental' , 7Mm of Fred English waste void space. potential for a much more ambitious issues of environmental impact had The contents of this article do not scheme emerged. By diverting the already been resolved to the client's The financial analysis examined the necessarily reflect the views al either the River, a single larger hill could be satisfaction. cash flows for each option for the client or the expert witness.

1. Top: The final landscape (WMDC, November 1991). 10

2. Left: Phasing of void space usage Limited scheme for both schemes CN'(WMJC, June 1991).

3. Right: Comparison of implicit cost 1987 1992 1997 2002 2007 2012 of waste void space CN'(WMJC and AEP. ._2______, 1991 prices, discounted at 7% per annum). 3

16 Fabric engineering: The Lee House experience Architect: Terry F•rrell & Co. 1. Detail of highly John Pilkington articulated facade. showing elements Neil Noble of stone, glass, and metal. (Photo: David Anderson David Anderson) In the beginning The term 'building fabric' is taken to cover all facets of building construction, from internal non-structural elements such as walls and 2. Typical technical screeds to external walls and roofs. With the cartoon produced move away from craft-based techniques to to assist architects. industrialized system technology for construct­ ing external fa9ades, it is this element of the fRESSl:C> """- ~ building which will benefit from greater engi­ COV'ER. 1N .AI..J,JMtNtU W'\ neering design input. The range of technologies Wrn-t available for use on building fa9ades is now " 51..A\/£ • LJN~ Ar a:::::iNt:,~ .:2>1N"CS more diverse than ever. An engineering approach is required to integrate these diverse technologies into the overall building envelope design, an approach that has been called 'fabric engineering'. Building fabric engineers as members of the engineering design team Sr',ll,.JHL.E'1!..S ~ ~ E. .STEEL ~ LINK. Wm,i should provide support to the architect by mak­ .sn::,,-' a ~~ ~ ing a contribution to all the technical design functions for the appropriate elements of the building envelope. The redevelopment of Lee House was con­ GON.,,..\JoO.S. N~ O~ ~P~D 3 \W CC>N E ceived late in 1985 as a response to a difficult S EAL "T"l:) GC,t-.FI:. ~~\ ~ development opportunity, the replacement of a AMb Gt:::::IN ~ uc::noN .::So"""1io:. '60s tower block by a new building capable of accommodating the most discerning of financial and professional organizations. The 57 OOOm2 building for MEPC is constructed partly on the site of the old Lee House and partly as an air rights structure across the intersection of Wood Street with London Wall, in the City of London. The architect, Terry Farrell & Co. (TFC) envis­ aged a highly articulated fa9ade of stone, metal and glass (Fig . 1) and early in 1986 began discussions on the possibility of Arups providing WIN DoW S:S-AN'8 ~ "t"ll\ai. technical advice on the design of these GON'nH lJo,l)S, *"='n~ elements. This was the catalyst needed to get NJE"oP"QANe. OR... • 1U C.OH Ii:. fabric engineering established. By mid-1987 the e'.)t"l"q.UI>ct) c.ot-.lN '=ic::"n>R scope of Arups' fabric engineering duties had been agreed. A team was established in Building Engineering Group 8 (now J), with members of Arup R&D providing specialist input where necessary; external consultants were employed where appropriate to advise on particular aspects of fabric engineering, e.g. fa9ade maintenance equipment. The Arup role The team provided technical support and advice to the architect on the following building envelope elements: (I)- PRESS. I> o«. Ei<-r'Rv e>eP • Waterproofing for basements, ground ~ IN l"\l....Of',I\ INIOM works, flat roofs and terraces @- ~ IN 'REOC~ • A panelized system of thin granite slabs sup­ G)-ALLlflAIN II.M ~ \CTRl.)S ICN ported on steel trusses @- :sut>e:: <=-rr CtW

90 •

0 -. Cl) 0) 80 -""' "'~ .D • • x 0 x )e Cl) • Cl r,;, c . '!l <( / 70 ?;;0 \>S' ,,. .'!,°" A o~ X Wet (pre 5/10/88) Ideal condition Ritt parallel to top of test ~ sample block • Wet (post 5110188) 60 7 8 9 10 11 12 13 14 15 16

B B

Rift dipping in direction of long axis of test sample block 90 x x

0 • Cl) • c 0) 80 ta"' ~ Rift dipping at right angles to long axis .D of test sample block 0 , Cl) ?$0 Cl c 'I'""' <( rof,:,~ x 70 ,,. Xo~ ~ x Dry 105°C (pre 5/10188) D Dry 60°C (post 5/10/88) Long skew to long axis of test sample • block 60 7 8 9 10 11 12 13 14 15 16 MOR (MPa) 3. Rift orientation. controlhng angle of breakage and distance from m1dpo1nt. 4. MOR values versus angle of breakage.

The few 'proper' drawings produced included 5 Glazed facade. with the 1960s' Royex House, London Wall . 1n the background. (Photo. David Anderson) elevations of the building showing anticipated movements such as foundation settlements, sway due to wind , movements from transfer structures, and axial shortening of columns and the effects of these on the cladding and roofs. Drawings were also produced of test specimens for full-scale testing of windows and walls, in· eluding typical wall features (gutters, corners, recesses. parapets. movement joints. etc.). assembled together to allow various details in the wall system to be tested for strength (ser­ viceability and safety), water penetration. and air permeability. Once the architect had developed his drawings from the technical cartoon stage. the Arup team carried out further technical audits on these drawings. Th is included a co-ordinating role with other engineering disciplines. Technical performance specifications were writ· ten. together with specifications for testing to establish compliance with these performance requirements, for 19 separate cladding pack· ages. Some were standard Arup specifications such as for brick and block, but the majority were brand-new. Many visits were made to potential cladding contractors to establish their resources and design and manufacturing capability, and reports prepared for the architect and client. 18 After contract award on all cladding sub· contracts, the most time was spent assisting the sub-contractors during their design develop­ ment process, confirming with them that they understood the requirements of the specifica­ tion. and reviewing their design drawings. The quality of the drawn information produced by the sub-contractors caused major difficulties. In many cases they were found to be so poor that every drawing had to be reviewed two or three times. On one cladding package alone this resulted in 1600 drawings having to be looked at, instead of the anticipated 50 or 60. Various tests were observed , from simple pull­ out tests on granite fixings and trial installations of wet seals to major weathering and structural tests on full-size specimens. Notes on the tests I I were written for the architect and client and I I testing house reports on these tests were reviewed. 60mm The fabric engineering team realised early in the erection process that Arups' structural. mech­ anical and electrical resident engineers were 6. Original architectural conception for mullion detail. not qualified to be 'fabric resident engineers', and that there were not sufficient staff to put appropriately qualified members of the fabric 60mm team on site. With the architect's and client's agreement. the team instigated a system of inspecting specific areas of each particular type of cladding to set quality standards. These inspections frequently took place in stages so that each element of the construction could be reviewed. Some interesting results --Et------Granite E The specification for the procurement of the ~- granite was drafted by Arup Facade Engineer­ ing in Australia and was developed out of experiences on Grosvenor Place. Sydney. Various strength and durability criteria were I- - - - specified including density. absorption, com­ pressive strength and modulus ot rupture (MOR) , all tested to American ASTM cpdes ------(there are no British codes). MOR is established from bending tests, earned out on samples cut parallel to the cleavage line or rift , and 65mm 10mm 65mm on samples cut perpendicular to the rift. Results were very variable, with quite a few fall ing below the specified minimum valves of 7. Modified mullion detail. 10.3MPa. An inspection of the test specimens at the testing laboratory established that the actual position of the rift in relation to the faces posed by a cladding project of this size and 8. Window - window mullion: detail. of the test specimen fundamentally affected the complexity. (Photo: Roger Ridsdill Smith) results (Fig. 3) . The future The closer the rift plane was to the orientation The lessons learned on the Lee House are being of the faces of the test specimen, the higher the evaluated and recorded tor future projects. In MOR values (Fig . 4 shows MOR values well particular, we are currently reviewing and above the specified minimum and close to the modifying specifications before our Lee House quoted value of 13 + MPa given in the supplier's experience is lost under pressure from the next trade literature). Hence the need to establish job. Th is will help future generations of fabric that the test specimen is cut correctly. engineers in Arups. Window mullions As a result of our experience on Lee House we A simple before-and-after comparison can be are obtaining other fabric engineering commis­ used to show typical results of fabric engineer­ sions ranging from conceptual engineering ing work. Fig . 6 illustrates what the architect advice to architects through complete design actually wanted to see. By the time the team had drawings and specifications for cladding pro­ discussed movements, tolerances, support jects io technical audits on building fabric and conditions for the glass, drainage, and what building pathology. A series of fabric initiatives happens at opening windows, it was acknow· are in place to develop standard forms of fabric ledged that the original architectural concept engineering conditions of engagement, bro­ needed to be modified to that shown in Fig. 7 chures, and explore new markets and new in order to achieve all the performance re­ technologies. quirements. This is a good example of an ini· We are playing significant roles in the work tiative approach being modified by engineering being carried out under the guidance of the input to give an appropriate design solution. Centre for Window and Cladding Technology Credits at Bath, we are assisting the BSI working Was the methodology successful? group involved with the production of Euro­ C/lent: There were difficulties persuading sub-con­ MEPC pie codes for cladding and we are involved with tractors that they really did have to allow for Architect: Institution of Structural Engineers on the pre­ building movements, drain water away, provide Terry Farrell & Co. paration of a cladding design guide for struc­ continuity of vapour barriers, etc., but many Management contractor: tural engineers. compensations also. Particularly satisfying was Mowlem Management Ltd. the gradual realisation by the client, architect The concept of fabric engineering , as another Quantity surveyor: and management contractor alike that the Arup skill in our industry remains controversial. Cyril Sweett & Partners fabric engineering team were the only ones who Whatever it is finally called and whoever does Illustrations: could resolve the complicated technical issues it. it will need doing even more in the future. Martin Hall 19 M•ln design crlterl• The National Gallery • To display some 240 paintings in a variety of media, including canvas, wood, fresco. tempera, Sainsbury Wing and oil (out of the National Gallery's collection of over 2000) • To maintain closely-controlled environmental Architects: Venturi and Scott Brown conditions 1n the Gallery and picture storage and packing areas, as listed below: Summer temperature 23°C with ± 1•c variation David Brunt Winter temperature 19°C with ± 1•c variation Seasonal temperature change of 0.25°C per week Alan Pepper Relative humidity 55% with a ± 5% variation • Special fillration to l1m1t gaseous pollutants such as sulphur dioxide. carbon monoxide and oxides Introduction of nitrogen. which can produce damaging acid This article is intended to illustrate and put into solutions when combined with the intersMial context key issues in the engineering design of condensation that can occur within the paintings the building. They are biased towards its en­ • To create a high mass building with an external vironmental systems because of their import­ thermal insulation value not exceeding 0.25W/m2°C ance for the display of the early Renaissance • To utilize controlled natural daylight to limit the paintings, which include some of the oldest in amount of harmful ultra-violet radiation to no more the National Gallery's collection, dating from than 650 kilolux hours per year. This permits 1260 to 1510 AD. average luminescence of approximately 200 lux The design submitted by Robert Venturi and during viewing time Denise Scott-Brown in January 1986 as part of • Low pressure hot water supplied from parent the selection process included a study of building at a temperature of 82°C renowned art galleries and the way in which the lighting of them served the best interests of the • Chilled water from parent building at 7.2°C. viewing public as well as preservation of the art works. Dulwich Art Gallery, designed by Sir The contracts John Soane. influenced their competition Late in 1986 the design teams and client design and illustrated the benefits of a pre­ advisors decided that the construction manage­ dominantly top-lit configuration, allowing max­ ment route was appropriate, and following sub­ imum use of wall space for display and good missions by a number of leading contractors Sir control of lighting through mixing natural and Robert McAlpine were appointed early in 1987. artificial light from above. It was originally intended that the total number The detailed brief listed the works to be of trade packages should be kept to around 20. displayed. and th is enabled the architects to with the structure and M&E services provided create gallery shapes which met the client's through 8. However, the large number of dif­ wishes for the arrangement of the paintings. ferent architectural finishes led to a significant This factor. together with the irregularly-shaped increase in the number of trade packages, with site, led to a totally asymmetric and non-modular a final total close to 50. plan at gallery level. This theme was extended to the other floors, two at ground level and A year's design work was carried out before the above, and two below ground, and has resulted appointment of the construction manager, dur­ in the creation of some generous and exciting ing which time Ove Arup & Partners attended public areas in which the architects have in to preliminary programming and site investiga­ places expressed their deep interest in 'con­ tion work, including an archaeological dig by tradiction and Juxtaposition '. the Museum of London.

3. The •ccommod•tlon Total floor area: 10 800m2 Colour key to all levels illustrated II>- O Gallery space • Other public areas

Level 1 Level2 Level3 (Main basement. 2000m2 net) (Basement mezzanine, 500m2 net) (Ground level . 1850m2 net) Galleries for temporary exhibitions Auditorium control and translation room Entrance foyer A 350-seat auditorium with stage Tunnel link to the main building Cloak storage A secure picture store with picture packing area Public toilets Shop A small video cinema (30 seats + standing room) Store Storage rooms and warders' rooms Twin vehicle loading bays Toilets Electrical plantrooms

20 General air plant

8

5. Basement undercroft. 2 6. Typical plantrooms 1 0

Undercroft Services void for link to clay heave main building

4 Longitudinal cross-section showing a1r-cond1t1oning.

Foundations Inclinometers were built into eight of the secant Superstructure It was necessary to ensure that ground move· piles to enable movements to be measured. The The irregular pattern of columns, and the re­ ments would not cause damage to adjacent sequence of excavation to full depth was care­ stricted headroom caused by the need to fit two buildings. and a movement monitoring system fully co-ordinated with the area-by-area casting storeys into the Sm height difference between was established to record the rate and extent of the basement floors that act as horizontal entrance pavement level and the link to the of movements over an area that included points props to the perimeter wall. This also minimized upper gallery of the existing National Gallery up to 60m from the site boundary. Actual hori­ lateral movements at the lower levels where building, led to the adoption of reinforced con' zontal movements proved to be approximately earth pressures are very large. crete flat slab floors on reinforced concrete half the value of those predicted by a finite The 20 000m2 of material that had to be re· columns. element mesh analysis, the largest being in the moved to form the basement was excavated The two loading bays, unavoidably situated order of 1Smm . through apertures in the ground floor slab within over the Level 1 auditorium. are of discon­ The building weight of approximately 25 OOO a five-month period as programmed. Beneath tinuous double floor construction with non-rigid tonnes is supported mainly on under-reamed the lowest basement a drained undercroft bearings to reduce the transmission of noise bored piles. but with a small proportion carried space (with minimum headroom of 750mm) was and vibration. by the perimeter secant pile wall. To minimize formed to allow the anticipated 1OOmm of clay The structural steel roof structure is geo­ horizontal ground movements, the ground level heave and to prevent any build-up of water metrically complicated because of the gallery slab was cast after piling and acted as a lateral pressure under the basement slab. This under­ plan layout. varying gallery heights. and the prop to the perimeter pile wall as the basement croft also allowed the drains to be laid after most need to provide routes for natural lighting and excavation was carried out 1n a 'top down' of the structure was complete, as well as pro­ the all important air-conditioning ductwork. approach. viding easy access to them for maintenance. Air-conditioning The need to provide high quality air and closely Non public areas Services plantroom • Lifts O Void controlled temperature and humidity conditions in the spaces containing the works of art led to the building being divided up into two basic zones. to cover critical and non-critical spaces. The air-handling system for the critical spaces includes activated carbon filtration and stringent hum1d1ty control whereas other areas did not require such thorough treatment. The carbon filters are located in the air-handling units where they are able to filter recirculated as , ... well as fresh air. The air-conditioning system is _.,,.~ controlled by a building management system (BMS). The critical system consists of two variable air volume air-handling units connected in parallel. From the air-handling units the air is fed through ductwork to the sub-zone areas where humidi· fication is adjusted individually. Each sub-zone serves up to six adjoining galleries. The humidity in each sub-zone is ad1usted by a pair of thyristor-controlled electnc steam humi· difiers. The air is supplied at a constant humidity of 80% and at a controlled temperature varying seasonally between 12°C and 15°C. We developed bespoke software algorithms to ensure that free cooling remained within Level4 Level 5 economic limits. (Mezzanine. 1700m2 net) (Main gallery, 1900m2 net) In every gallery there are three wall-mounted Micro Gallery 16 gallery rooms sets of sensors that measure temperature and RestauranUkitchen/cottee bar Link to the main building humidity. The closest values from two of the Trustees' conference rooms Store sensors are automatically selected and the third Warders rooms Levels 6, 7, 8 (not illustrated) one rejected. This redundancy approach was a Public toilets (Plant rooms. totalling 11 OOm2 net) requirement of the brief and provides some pro· tection against sensors going out of calibration. The BMS is used to provide close control, 21 Gallery llghtlng survey of reverberation times in a selection of The benefits of some degree of day-lighting, galleries 1n the main building as well as in the which include outside awareness and change­ Tate Gallery revealed four different characteris­ ability, outweigh the harm from its transmission tic shapes to the reverberation time against of ultra-violet radiation, particularly when the frequency curves. The brief laid down that 'large latter can be strictly controlled. As the UV radia· areas of highly efficient acoustic absorbent tion does not contribute to the visual process, material should be avoided' and the end result it is normally controlled in all modern museums was the incorporation of Mikropor perforated and galleries to a level of 75µW per lumen. In panels into the ceilings and inclined areas the Sainsbury Wing the acceptable level 1s a between walls and clerestory glazing. Acous· more stringent 1OµW per lumen. llcal advice for all aspects of the design of the Above the clerestory windows to the galleries building was provided from the concept stage and beneath the main roof-line are illuminated onwards and was of considerable influence on walkway routes that accommodate a network of the design of the auditorium as well as the isola· blinds automatically operated to control the t1on of high noise levels in local streets. amount of natural lighting passing to the Ufts galleries below. There are two passenger lifts for public use and A 1 : 5 scale model and a full-scale mock-up of two additional special-purpose hydraulic lifts. gallery space were used early in the project to One is a picture lift with large-volume car capa­ test the design assumptions and to confirm the city, rated at 5 tonnes, whilst the other is a small final brief. As a result, artificial lighting was incor· kitchen lift serving the ground floor and mezza­ porated at high level to complement and sup· nine levels only. plement daylight for viewing, and as a main Conclusion source during the hours of darkness. It also pro­ Construction commenced in mid-January 1988, vides illumination for security and maintenance. and HRH The Prince of Wales. who is a National The lighting angles have been designed to Gallery Trustee, laid the foundation stone in avoid reflective glare from the paintings and the March that year. The building was occupied by picture lights are track-mounted 12V tungsten National Gallery staff 1n late autumn 1990, so halogen fittings 1n a recessed slot around the that they could embark on the fitting-out and picture hanging work. After building handover, perimeter of the lantern ceiling and across the maximum energy efficiency, and monitoring of centre of the larger galleries. the simulated load tests were carried out on the plant performance. It is also the basis of efficient air-conditioning. These tests provided add1· Fire precautions tlonal conf1rmat1on to those responsible for the maintenance procedures. Standard and A detailed fire strategy evolved from discussions specially written software has been used to collection that the environment in the Sainsbury between Westminster City Council, the architect Wing was stable and fully controlled before any provide a comprehensive control and monitor· and ourselves. Protection of the paintings ing system. exhibits were transferred from the main includes prevention of water damage from inter· building. The building was finally opened by the Load simulation tests were earned out after nal sources and rainwater drainage. A sprinkler Queen on 9 July 1991 . completion to represent the design occupancy installation was not included in the original brief of a person for every 4m2 of floor space. Arrays but we convinced the client that sprinklers Computer technology has been incorporated of 100W bulbs, each representing one person, should be included in certain non-gallery areas. by National Gallery staff for the benefit of the were used to simulate sensible heat. Latent heat A single sprinkler coped with the firebomb that viewing public in the information room on Level was simulated by electric kettles wired through went off in the shop during the early hours of 4. This contains a 'Micro Gallery'. thought to be variax transformers to give an evaporation rate Sunday 15 December 1991 . the most advanced fully-d1g1tal interactive media system of its kind in the world, being equal to 60W per person. An appropriate The high security requirements of the building correction for the sensible heat loss of each able to display over 2000 paintings with many necessitate that smoke extraction be by secondary illustrations, texts and animated kettle was made by adding 1OOW to the kettle mechanical means. The air-conditioning sys­ supply and taking out one of the 1OOW bulbs. sequences. These are reproduced on Radius tems' return air ductwork, suitably fireproofed, 19in colour monitors providing a screen resolu· The control signals to the BMS were monitored 1s used to draw smoke from the area of the lion of 82 dots per inch . The installation during the testing and only minor re-tuning of building affected by fire. Smoke extract fans comprises 12 Apple Macintosh llfx computers controls to reduce VAV box cycling was rated to withstand 615°C for a period of 90 each with 8MB of RAM and a dedicated 1 3 necessary to achieve design conditions. minutes are linked to return air ductwork via gigabyte hard disk drive. The system runs suffl· Smoke testing was carried out both during and dampers isolating the normal return air fans. c1ently fast to permit the viewer to browse independent of the occupancy load s1mulat1on Acoustics through 1t using the touch screen with an access to demonstrate that air velocities could be kept Enjoyment of the pictures, with adequate intel· time of no more than one second from screen low and reasonably uniform within the occupied ligibility for effective guidance. were the prime to screen. Another example of Art and Science space and its surrounding walls. acoustical requirements in the gallery areas. A blending happily together!

7 Level s· view through hnk to existing National Gallery 8 Smoke extract fans 9 Level 1 aud,tonum.

22 Credits . Ghent: ,• N.G. Services Ltd. , ~ , , . (a company formed by the Donors _.. .· .· solely for the prov1s1on of the bu1ld1ng) · .. · Architects: 4i,!i'. .. Design: Venturi Scott-Brown Associates UK liaison: Sheppard Robson Structural engineer: Ove Arup & Partners M&E services engineers: Ove Arup & Partners Jaros Baum & Bolles (New York) Quantity surveyors: Gardiner & Theobald Mott Green & Wall (BuJlding Services) Lighting design: Fischer Marantz Acoustics: Arup Acoustics Construction manager: Sir Robert McAlpine Construction Management Ltd. M&E services installation contractor: Crown House Engineenng Ltd. Photos: 1: Ernie Hills; 2: David Brunt; 5-8, 10-11 : Peter Mackinven; 9: © National Gallery Publications Ltd. Illustrations: Fred English

10. Clerestory glazing showing natural lighting control mechanism. 11 . Typical gallery.

23