Football Stadium Terraces: Sheffield Wednesday's Leppings Lane Study, Study notes of Engineering

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• ANNEXE

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Dr C E Nicholson

HILLSBOROUGH INQUIRY - CROWD DENSITIES AND PRESSURES

1 Further to my note of the 1 May. I have been able to make some progress with

my enquiries and discuss these below.

A The capacity of the terraces

2 In correspondence obtained from Dr Eastwood it appears from his report to the

directors of Sheffield Wednesday Football Club Ltd and from the application he made on their behalf for a safety certificate dated 12/1/79 and 17/1/79, he proposed that the numbers of persons using the Leppings Lane terraces should be restricted to 7,200. This is 10% less than the maximum that could be allowed in the area using the Green Guide figure of 54 persons to 10 sq m. The 10% being deduced because there were no gangways within the terrace area.

3 The rough figures used to calculate the area of the terraces to obtain the

crowd capacity are also on the file and from these it is possible to plot on drawing 1610/64E the area that was considered in making these proposals. This

is the drawing I have been given as showing the current position of the

terrace capacity. This drawing indicates that the total capacity of the same areas of terraces referred to in the January 1979 correspondence is still 7,200.

4 From drawing 16 10/64E the areas of the pens and the numbers of persons who

could use them at 54 persons per 10 sq m less 10%, are shown in the table below together with the capacities given on drawing 1610/64E.

Numbers given on drwg 1610/64E

m X 5.4 X 0.9 = 2588

966(927)

322 I^ I 1564

Total 1461.7 (^) 7101(7018)

S.W. corner pen 532.6 sq

Central pen 198.8 sq m(190.8)

Central pen 201.6 sq m(192.4) 979(935)

N.W. end pen sq m

N.W. (lower) corner pen 206.7 sq m

acceptable even when considerable latitude had been given. For instance if only those barriers which meet the Green Guide recommendations were used in this calculation, the allowable numbers of persons able to use the central terraces would drop to 389 and 540.

12 A search through the correspcndence may throw more light on how the

designated numbers were chosen and accepted, and on why other barriers were installed at later dates as shown in the revision notes on drawing 1610/64E.

13 It is probable that a member of the Safety Committee attended the Home Office Seminar in 1972 referred to in para 16 and should therefore have been quite clear how the Green Guide was to be applied even though the Guide itself is a

little ambiguous. I hope to obtain the delegate list of those who attended

the Seminar.

14 It is clear that some barriers have been removed from the central pens over the last 10 years when Dr Eastwood made his original proposals. If left in place some of these could have increased the area calculated in paras 9, l and 11, which could be designated for spectators. Further searches will have to be made to find out their detail and the history of their removal.

l5 All which I have said above assumes that the barriers are perfectly adequate

to carry their loads, and ignores the effect of connecting a downward sloping tunnel, of the length noted at Hillsborough, directly into the terraces.

16 From conversations we have had so far with Dr Eastwood I query whether the test procedures used, could categorically guarantee the reliability of the barriers. That is whether the tests would pick up all the weaknesses in the barrier.

17 It appears that the test procedure was only nominally as required by the

Green Guide i.e. in loading the barriers three times. I do not believe ac

the moment this would be very significant, as the required procedure seems a little excessive. However as an indication of the state of affairs, it seems that Dr Eastwood and his staff thought they were implicitly following the Guide.

18 The procedure as I presently understand it, could have resulted in the end

frame in bay 1, not being measured for permanent deflection. (See the notes of my telephone conversation with Dr Eastwood, 5/6/89 in reply to question 3 ).

B The reconmendatons of the Green Guide in respect of the barriers and crowd densities

19 I have had discussions with Brian Stickley of the Home Office Prison Service.

He is the structural Engineer who worked out the structural provisions in the Green Guide and is probably the most informed person about what was intended to be in it and what research or other information was available as a basis

for those provisions.

20 Mr Stickley clearly believed that both the provisions of the Green Guide were

exceeded and had they been complied with, then the number of injuries could have been greatly reduced, if not avoided altogether. The basis of this comment was not just that the designated crowd densities were too high because of the position, number and height of the barriers, but also that the Guide's recommendations on stewarding were not followed. Clearly a huge influx of fans down the tunnel, whatever the level of occupancy of the terraces, was potentially hazardous.

However there are certain inconsistancies with his comments. Mr Stickley has agreed that many of the provisions of the Guide are vague, almost ambiguous. (This is further discussed in Appendix 'A' giving abstracts from the Guide with comments). He stated that this was deliberate because there are so many grounds with widely different characteristics that it would be impossible to give definitive clauses without either unnecessarily penalising some and being too lenient with others. However it was expected in the Guide that the engineer working for the club would use the background philosophies from the Guide and relate these to any particular ground. Hence when the Guide was launched in 1972 a seminar was organised by the Home Office for members of the safety committees, in which Mr Stickley explained how the engineering provisions of the Guide should be applied, in particular how to work out the safe number of persons who should use the terraces.

22 While this may seem reasonable, a problem could have been caused because the Green Guide does not clearly describe the difference between its general

the funnelling effect is of little consequence, while egress will nearly always be in mass when the fanning out effect is highly desirable.

28 The guide is reasonably firm about the height of the barriers although the stress on the idea that it is a "voluntary code" and "should be interpreted^1 ' at the beginning of the Guide could weaken the importance of having barriers at the correct height. The Wheatley Report, from which the Guide was drawn, expresses the height recommendations much more strongly e.g. the height of crush barriers should preferably be 3'-6" above the ground". In all cases they should be between 3'- 4 " and 3'- 8 "'. Clause 23.5 'Report of the Inquiry into Crowd Safety at Sports Grounds' by the Rt Hon Lord Wheatley.

29 The recommendations concerning height appear to have been determined "In order to locate the top rail against that part of the body most able to tolerate pressure" (para 110). There seems some evidence that depending on the density of the crowd, a low barrier allows a body to bend over the barrier, passing the force it is subjected to, to those in front. This action could make low

barriers largely ineffective.

30 The testing of barriers described in Annex "C" fails to make a recommendation

about the maximum deflection. Strict interpretation could result in barriers that move 1 mm yet fail to recover 0.5 mm being failed, while those that move 100 mm and recover 75 mm being passed. Although the examples given are extreme they do illustrate that without skilled examination and interpretation of the results, the tests could encourage the acceptance of weakened barriers, while rejecting others that were satisfactory. Paragraph 6 of the Annex does point out that barriers should be examined if any doubt exists about their strength, but the lack of more positive advice could easily lead to a vice variety in the quality of barriers across the country.

3 1 Paragraph 6 of Annex "C" (^) says that detailed investigations should be carried

out where there was doubt about the safety of the barrier, such as might be indicated by the distortion of connections. Quite a few of the barriers now show distortion and I question when this occurred.

32 When referring to the packing density on terraces in para 221, little or no guidance is given on the criteria which should be used to govern the variation between 27 and 54 persons per 10 sq metres.

33 In the 1946 Hughes Report on the disaster at Bolten Wanderers Football ground a maximum packing density of 6.5 persons per metre was recommended. This was reduced to 5. 4 in the Wheatley Report. Dr^ Eastwood has suggested that average densities of around 8.5 were achieved immediately post war,,which is similar to that which must have occurred on the terraces at Hillsborough.

34 Examination of the videos appear to show an increasing variation in density

from the back to the front, while those at the centre of the terrace do not appear to be unduly worried by their situation. Initial estimates from the video suggest the density varied from about 6 to 10 or 11 persons per sq metre, so that those in the centre were at around 8 persons per sq metre.

35 This raises the question of what are suitable densities? If 6. 4 was acceptable in 1946 and 5. 4 in 1972, should the Green Guide's criteria be revised again? It might be that people today are generally larger and more restless, requiring more space, apart from any trend towards the public expecting more comfortable conditions.

Further work

36 The maximum crowd densities for various situations should be more adequately researched. Some work might be possible from the photographs and videos of Hillsborough, countingthe number of persons in the situations where they are obviously a) contented, b) overcrowded and c) in distress. This work could be reinforced by packing people into given areas and counting the number of teenagers, women and mature men that will accept various densrties.

37 Work should be undertaken to check out suitable heights and construct'ion of barriers, in particular measuring the most effective height that will stop or suitably reduce a crowd surge.

38 Finally, research should be undertaken into modelling the pressures and densities in the crowd at Hillsborough so that alternative layouts can be tried out and the most suitable layout of barriers and exits can be

discovered. I originally considered that a hydraulic model might be suitable

a p p r o a c h

not

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APPENDIX A

REVIEW OF THE CLAUSES RELEVANT TO CONTROLLING THE DENSITY OF SPECTATORS ON

TERRACES FROM THE "GUIDE TO SAFETY AT SPORTS GROUNDS" (THE GREEN GUIDE)

1 This booklet provides guidance to ground management, local authorities and technical specialists such as engineers on measures for improving spectator safety at existing sports grounds. It is a voluntary code and has no legal force.

4 The problem of crowd safety at sports grounds is complex and cannot be solved simply by ensuring that each component of a ground, such as stairways, passages or sections of terracing, is satisfactory in itself. The inter-relation of these and other components is essential: none of them can be considered in isolation without consideration of its effects on the others, and they should all compatible and combine to form a balanced

(^6) Deviations from individual guidelines are possible without necessarily detracting from the overall safety of the ground. (^) The variety of type, function and layout of sports grounds and the inter-relationship of the different parts of them means that a flexible should be maintained to take account of the particular circumstances at individual grounds. for these reasons the Guide does attempt to set a minimum standard which would be acceptable for a well-attended stadium but excessive for a smaller, sparsely-attended ground; or which would be an appropriate standard for the latter but insufficient for the former.

8 It should be borne in mind that, when using the Guide to assess whether existing circumstances provide adequately for the safety of spectators, the criterion to be aimed for is that of a reasonable degree of safety. It would be unreasonable, even if it were practical, to seek the absolute safety of everyone actending a ground.

........ the guide is an (^) to, not a substitute form, professional judgement and common sense.

13 It follows general in a ground where it is propsed to retain a high speccator capacity, the measures needed to be taken to accommodate safely such large crowds are potentially more extensive.

The guide continually stresses its voluntary nature and that a considerable amount of interpretation is permissible or even desirable.

Once again great stress is laid on the need for intelligent assessment of the guide's provisions.

As above.

Such terms are meaningless, how many injuries are acceptable?

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even im their movements.

help.

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systems.

them.

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8 - S l o p e s

made

local

proportions.

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t p a i n tand

there.

The second type is far more important and involves crowd pressures. When large crowds are present and densities are high, pressures build up within the crowd either through motion or swaying which make it difficult, or ossible for individuals to control Under these conditions crowd pressures can escalate to a dangerous level and if a person stumbles or falls the crowd cannot adapt to avoid him or to stop to Since this type of danger arises from crowd pressures its remedy lies in their removal or restraint within safe limits. These dangers arise in particular on te and exit routes, and so careful attention must be paid to restraining surges and similar pressures on the terraces and to ensuring free movement throughout the exit Such free movement is dependent upon the capacity of all the various sections of the exit systems and interactions between

Barriers not only serve to break crowd pressures but also assist in controlling movement off the terraces by regulating the rate of arrival at exits to suit their capacity, and encouraging the formation of queues so that spectators arrive at exits in an orderly fashion.

Prelim. to Ch. Terraces and Viewing

Arrangements should be to encourage the even distribution of the crowd on the terraces to provide ease of access and egress: to control and facilitate movement, particularly if a emergency should arise during the event; and to contain pressures before they reach dangerous The provisions set out here will assist in achieving these conditions (i.e. paras 89-109).

The aim should be to ensure that every spectator on the terraces is within 12 metres of a gangway or exit, so that spectators can move quickly on to exit routes at the end of an event or in the event of emergency...

Where sinking gangways, lateral or radial, is not thought to be prac ical, their boundaries should be hiqhlighted with spectators advised by signs not to stand

To some extent there is a conflict of interests in "restraining surges" but "ensuring free movement" through the exit systems. Comments about the height of barriers would have been particularly useful here.

Gaps in barriers which will allow filtered approach to the exits can allow crowd surges to develop.

It seems quite clear thet the layout at the Leppings Lane terraces discouraged an even distribution of people. encourage is a rather weak requirement, this provision is essential. If the provisions will only assist then additional engineering input is required IN ADDITIoN TO THE GUIDES RECOMMENDATIONS.

"advised" by signs is rather a weak piece of advice.

Crowd oovement on terraces should be strictly c o n t r o l l e din order to give the police the fullest opportunity for crowd control. (^) Less problemsoccur when terraces are subdivided as far as possible into sections by use of both radial and lateral barriers or railings which should comply with the strength

requirements set out in Ch. 9. .....

Access to the pitch must be made as difficult

as possible in normal circumstances .....

..... Gates or other access points (minimum

width 1.1 metres) should nonetheless be

provided for use in an emergency ....

I

..... This section suggests a method of l

calculating the number of people that can be 1

safely accommodated when taking into account ,I

interactions between these individual I features and where there are deviations from 1 the guidelines. The following paragraphs

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contain as of necessity generalised guideline

in view of the wide variety of types, sizes, l

configurations of sports grounds, their use I

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from the area available for standing (^) by

and condition.

Where crush barriers meet the strength and spacing guidelines of Ch. 9 the capacity of terrace or viewing slope should be assessed

allowing 54 and 27 persons per 10 sq metres depending upon the condition of the terrace or slope. .... i 27 persons per 10 sq metres when it l materially deviates from the recommended

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guidelines, so as to constitute a possible

hazard to individuals closely packed. i

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..... When the positioning and length of i

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gangways do not meet with the recommendations I

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of Ch. 8, paras 96-100, an appropriate reduction should be made to the area (^) I available for standing. (^) I

Even distribution of spectators on the terrace may be difficult to overcome notwithstanding the measures in this guide, because spectators may prefer to gather in certain parts or parts of a terrace. (^) Ground management should therefore take such factors into account when assessinq safe c a p a c i t y levels.

226 When the strength of crush barriers conforms No reference to the height with the guidelines but the spacing of such of the barriers. barriers does not, the capacity is calculated from the provision of crush barriers in the area available for standing (as defined in para 221) as follows:

(a) Where a terrace contains either^ "peak viewing areas" only or "other viewing areas", by multiplying the total length of the crush barriers by an appropriate distance between barriers (as given in Ch. 9, paras 116-117) (^) or the existing distance, whichever is the (^) less, and multiplying by the appropriate packing density.

227 Crush barriers which do not meet the guidelines on the strength set out in Ch. 9 should be discounted for calculation purposes, although where crush barriers are well constructed, consideration may be given to allowing a lower packing density figure for the purpose of the calculation.