This page contains a Flash digital edition of a book.
reduced the impact on the environment. This was a particularly important consideration for Westfi eld as Stratford City has been designed to achieve excellence in environmental sustainability.


Under-balcony smoke screens All multi-storey shopping malls are provided with smoke curtains or glazed screens on the lower levels, beneath the balcony ceilings. This is based on research from 20 years ago that showed extensive lateral smoke spread could occur beneath balconies. These screens channel smoke through the voids, ensuring a compact smoke plume. There have been signifi cant advances in sprinkler technology, reducing the risk of larger fi res in modern shopping centres. To keep company engineers busy in 2009/2010


PLAN KEY


Screens to be retained


Screens not needed


Shop fi res modelled


during the economic downturn, JGA devoted time to smoke modelling research projects. The impact of smaller fi res and the need for under-balcony smoke screens was reviewed, together with Westfi eld, led by director of design and construction Keith Whitmore, were key drivers in providing JGA with the support and funding to develop this research. It analysed 24 different fi re scenarios and took more than 1,000 engineer hours spread over 15 months to complete. The results allowed nearly all of the under-balcony smoke screens to be removed at the middle level (see diagram below). This simplifi ed coordination of the ceilings and resulted in much less impact on tenants’ shop-front designs.


Lower ground fl oor Typically, shops at the lowest level of a three-storey mall are provided with their own smoke-control system of downstands or smoke curtains on the shop front, which form the smoke reservoir. At Stratford City this would have resulted in nearly


800m of smoke curtain. A series of models were constructed to analyse smoke movement from a lower ground fl oor shop fi re to determine whether fans in the roof could deal with the smoke produced. By providing a few under-balcony smoke screens beneath the bridges it was possible to omit the smoke curtains at the shop front.


Mall escape routes While this comprehensive package of fi re-safety measures means the mall should theoretically be safe for the duration of a fi re, it is essential that there are escape routes of suffi cient size to deal with the potential high volume of people the centre could feasibly hold. The key was providing these in the right areas. Research has proven that human behaviour,


and in particular exit choice, is a fundamental consideration in providing a safe escape from public buildings. Evidence from real fi res has shown that occupants are willing to travel much further, often past emergency escape corridors, in order to reach escape routes they are familiar with, such as a main entrance from the street or car park. JGA worked with the designers to maximise


familiar routes as the primary escape means. The geometry of the centre and the connectivity with Stratford International station towards the Olympic Park leant itself to this. There are 13 entrances in total, either to the surrounding streets or adjoining car parks, with at least one on every level. This allowed dedicated emergency-only exits to be kept to a minimum. The distance between exits on the lowest two fl oors was increased from the standard 90m to a maximum of 120m, refl ecting the high standard of safety that such a ‘cathedral’-like space provides. This gave more fl exibility to accommodate changes to the retail plan at these levels.


61


4. Diagram showing under-balcony screens plan


4


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142