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S T D - B S I B S 7121: P A R T 5-ENGL 1997
üb25432 T O 1
BS 7121 :
Part 5 : 1997
BRITISH STANDARD
Code of practice for
Safe use of cranes
Part 5. Tower cranes
ICs 53.020.20
PYING
SI PERMISSI
AS PE
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COPYRIGHT British Standards Institution on ERC Specs and Standards
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IG
BS 7121 :Part 5 : 1997
Committees responsible for this
British Standard
The preparation of thisBritish Standard was entrusted to Technical Committee
MHE/3, Cranes and demcks, upon which the following bodies were represented:
Associated British Ports
Association of Lorry Loader Manufacturers and Importers
British Iron and Steel Producers’ Association
Building Employers’ Confederation
Constsuction Plant-hire Federation
Electricity Association
Engineering Equipment and Materials Users’ Association
Federation of Manfuacturers of Construction Equipment and Cranes
Federation of Wire Rope Manufacturers of Great Britain
Health and Safety Executive
Institute of Logistics
Institute of Mechanical Engineers
Institute of Occupational Health and Safety
Institute of Plant Engineers
Institute of S t r u c m Engineers
Lifting Equipment Engineers Federation
Lloyd’s Register of Shipping
Safety Assessment Federation LM.
The foliowing bodies were also represented in the drafhng of the standard, through
a subcommittee:
Amalgamated Engineering Union (Constmction Heaìth and Safety Group)
Federation of Civil Engineering Contractors
Institute of Civil Engineers
Oil and Chemical Plant Contractors’Association Ltd.
This British Standard, having
been prepared under the
direction of the Engineering
Sector Board, was published
under the authoriw of the
Standards Board and comes into
effect on
15 July 1997
O BSI 1997
AmdNo.
Date
Text affected
The foliowing BSI references
relate to the work on this
standard
Committee reference MHEí3
Draft for comment 92/71042 DC
ISBN O 580 25805 X
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S T D - B S I B S 7121: P A K T 5-ENGL 1777 E L b 2 4 b b 9 U b 2 5 4 3 4 A B 4
BS 7121 : Part 6 : 1997
Contents
Committees responsible
Foreword
page
Inside front cover
11
Code of practice
1
1 scope
1
2 References
1
3 Definitions
1
4 Management of the lifting operation
1
6 Planning the lifting operation
2
6 Selection and duties of personnel
2
7 Attributes of personnel
3
8 Selection of tower cranes
11
9 safety
12
10 Siting of cranes
13
11 Erecting, dismantling and aiteration of height
14
12 Procedures and precautions
15
13 operating conditions
15
14 Testing and examinaton
16
16 Legai requirements
16
16 Ropes
16
17 Slinging and handling of loads
16
18 Raising or lowering of personnel
16
19 signalling systems
16
20 m
g and guying
16
21 Signboards
"
Annex
(informative) Specimen copy of informaîion sheet RA 195 published by
A
17
the Radio Communications Agency
Figures
1
Qpesoftower
5
2
of jib
6
3
mesofbase
8
4
Low mounted tower crane
10
Inside back cover
List of references
mes
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S T D - B S I B S 7121: P A R T 5-ENGL 1 7 7 7
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BS 7121 :Part 5 :1997
Foreword
This Part of BS 7121 has been prepared by Technical Committee MHE#. It provides
recommendations for the safe use of tower cranes. It should be used in conjunction
with BS 7121 : Parts 1and 2, to which specific references are made.
It is in the interest of all parties involved in lifting operationsto ensure that these
operations are carried out efficiently and safely. This Part of BS 7121 has been written
to provide recommendations for the safe use of the tower crane at all stages of its
utilizaton.
This Part of BS 7121 is commended to owners and users of tower cranes, who are
encouraged to observe all the recommendations, and where possible, upgrade emsting
equipment and operating procedures accordingly.
Whilst it is recognized that the recommendations given do not relate to the design and
manufacture of tower cranes, designers are strongly advised to take them into
consideration.
This Part of BS 7121 is one of a series of standasds entitled Code of pmcticefor safe
use of c r a m as follows:
Partl. GfYnEmL
Part 2. Inspection, testing and exurnimttion
Part 3. Mobile cranes1)
Part4. Lorryloaders
Part5. Towercmnes
Part 6. Derriclc munes1)
Part7. íhwhedunderhung tmvding and goliath mm')
Part 8. High pedestal and portaE jib cranes1)
part 9. Container h a d i n g maw')
part 10. RU~Jmounted cmnesl>
part 11. ûfls/tm-emnesl)
It has been assumed in the draffing of this British Standard that the execution of its
provisions is entrusted to appropriately qualified and experienced people.
A s a code of practice, this British Standard takes the form of guidance and
recommendations. It should not be quoted as if it were a specification and particular
care should be taken to ensure that claims of compliance are not misleading.
Annex A is reproduced with permission of the RadioconununicationsAgency.
Attention is drawn to relevant legislation and, in pAcular, to statutory requirements
for the testing and examination of cranes.
Compliance with a British Standard does not of itself confer immunity
from legal obligations.
Summary of pages
This document comprises a &ont cover, an inside h n t cover, pages i and ii,
pages 1to 18, an inside back cover and a back cover.
i) in preparation.
ii
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S T D - B S I BS 7121: P A R T 5-ENGL 1717 U 1 b 2 4 b b 7 Ob2543b b 5 7 M
BS 7121 :Part 5 : 1997
Code of practice
1 Scope
4.2.2 Other particulars
This Part of BS 7121 gives recommendations for the
safe use of tower cranes. It should be read in
conjunction with BS 7121 : Park 1and 2.
Subjects covered include planning the installation,
erection, testing, maintenance, operation and
application, dismantling, and transportation, as well
as safety measures to be taken during the execution
of all the above functions.
It also covers the appropriate selection of personnel
for safe use of tower cranes.
NOTE. Reference is made to different types of tower crane and it
On sites where there is more than one tower crane
and there is a possibility of collision between cranes,
a person, the crane coordinator (see 6.3.2), should
plan the sequence of crane movements to prevent
collisions. Any corresponding instructions from the
crane coordinator to the crane drivers should be via
the respective signallers. In such circumstances the
signallers should obtain the agreement of the crane
coordinator before canying out any operation.
Where tower cranes inter-arc, a vertical distance
should be maintained to prevent collisions. This
distance should be either:
a) a minimum clearance of 3 m; or
b) a minimum clearance of 600 mm plus the
manufacturer’s deflections where full details are
available from the manufacturer.
The positioning of the crane and components in the
out-of-service condition, as specified by the
manufacturer’s instructions, should be such that no
collisions can take place (see 12.4b).
should be noted that these types are often combined, for example,
seìf-erecting, raiimounteà, luffing jib.
2 References
2.1 Normative references
This Part of BS 7121 incorporates by dated or
undated reference, provisions from other
publications. These nonnative references are made
at the appropriate places in the text and the cited
publications are listed on the inside back cover. For
dated references, only the edition cited applies; any
subsequent amendments to or revisions of the cited
publication apply to this Part of BS 7121 only when
incorporated in the reference by amendment or
revision. For undated references, the latest edition of
the cited publication applies, together with any
amendments.
2.2 Informative references
This Part of BS 7121 refers to other publications that
provide information or guidance. Editions of these
publications current of the time of issue of this
standard are listed on the inside back cover but
reference should be made to the latest editions.
3 Definitions
For the purposes of this Part of BS 7121 the
definitions given in BS 7121 : Part 1: 1989 apply,
together with the following:
zoning device
An electromechanicaYelectronic device to control
the zone in which a tower crane works.
4 Management of the lifting operation
4.1 Safe system of work
Reference should be made to 3.1 of BS 7121 :
Part 1: 1989.
4.2 Control of the lifting operation
4.2.1 General
Reference should be made to 3.2 and 3.3 of
BS 7121 : Part 1: 1989.
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4.3 Duties of the person appointed to control
the lifting operation
Reference should be made to 3.3 of BS 7121 :
Part 1: 1989.
In the interests of safety the appointed person
should arrange the lifting programme such that no
one driver has to be in attendance at the control
station or actually operating the crane for an
unreasonably long period, taking into account
environmental conditions. The driver should have
breaks from the working activity in line with other
personnel on the site.
4.4 Contractual considerations
4.4.1 Contract lfling operations
Reference should be made to 3.4.1 of BS 7121 :
Part 1: 1989.
4.4.2 User’s duties when using hired cranes
Reference should be made to 3.4.2 of BS 7121 :
Part 1: 1989.
5 Planning the lifting operation
6.1 General
Reference should be made to clause 4 of BS 7121 :
Part 1 : 1989.
6.2 Other particulars
If the slinger or signaller is required to carry out a
liftiig operation which is outside the existing plan,
the appointed person should be alerted. The
appointed person should delay that particular lifting
operation until a plan can be prepared for it.
1
6 Selection and duties of personnel
7 Attributes of personnel
6.1 Selection
Reference should be made to 6.1 of BS 7121 :
Part 1: 1989 and 6.1 of BS 7121 : Part 4 : 1997.
7.1 Crane driver
Reference should be made to 6.1 of BS 9121 :
Part 1: 1989.
Tower crane drivers can be required to climb to
considerable heights and to spend long periods of
time in isolation. Thii should be borne in mind when
selecting tower crane drivers.
6.2 Duties
6.2.1 Crane driver
Reference should be made to 6.2.1 of BS 7121 :
Part 1: 1989.
7.2 Slinger
Reference should be made to 6.2 of BS 7121 :
Part 1: 1989.
6.2.2 Slinger
Reference should be made to 6.2.2 of BS 7121 :
Part 1: 1989.
6.2.3 Signaller
Reference should be made to 6.2.3 of BS 7121 :
Part 1: 1989.
7.3 Signaller
Reference should be made to 6.3 of BS 7121 :
Part 1: 1989.
6.2.4 Crane erector
Reference should be made to 6.2.4 of BS 7121 :
Part 1: 1989.
7.4 Crane erector
Reference should be made to 6.4 of BS 7121 :
Part 1: 1989.
6.2.6 Maintenance personnel
Reference should be made to 6.2.6 of BS 7121 :
Part 1: 1989.
7.6 Maintenance personnel
Reference should be made to 6.6 of BS 7121 :
Part 1 : 1989.
In addition, the maintenance personnel should be:
a) fully conversant with the appropriate sections
of the manufacturer’s instruction m a n w
b) familiar with the ‘permit to work system where
it is required by the safe system of work, and able
to operate it correctly;
c) familiar with all aspects of their personal
protective equipment and capable of using it
correctly.
6.2.6 Crane coordinator
The crane coordinator should plan the sequence of
operations of tower cranes on sites having more than
one crane, to ensure that cranes, components and
loads do not collide.
6.2.7 Crane erection supervisor
NOTE 1. The crane erection supervisor is the ‘erector in charge’,
as detaileà in 5.2.4 of BS 7121 : Part 1 : 1989.
The crane erection supervisor should have the
responsibilities of a crane erector plus the following.
a) The crane erection supervisor should be in
control of ali crane erectors and of any additional
cranage and lifting equipment which may be used
in the erectionldismantling operation.
b) The crane erection supervisor should provide a
means for ensuring that the operation is carried
out in accordance with the crane coordinator’s
plan.
c) Additional cranage and equipment should be in
accordance with that specified and properly
certified.
d) All erectors should be equipped with the
necessary tools and personal protective equipment.
NOTE 2. The appointed person (see 3.2 of BS 7121 : Part 1 : 1989)
retains overall responsibiiity for the erectioddkrnantling
operation, including the planning.
If the crane erection supervisor has to leave the site
of the operation, even for a few minutes, he or she
should appoint another member of his/her team to
be in charge during the period of absence, in order
to prevent any ambiguity as to the control of the
operation.
NOTE 3. The crane erection supervisor should attempt to remain
on site throughout the whole of the erectioddkmantiing
operation.
7.6 Crane coordinator
The crane coordinator should be:
a) competent;
b) over 21 years of age unless under the direct
supervision of a person competent for the
purposes of training;
c) fit, with particular regard to eyesight, hearing,
reflexes and agility;
d) experienced for at least five years in the use of
tower cranes;
e) trained in the techniques of signalling and with
a good understanding of the signai code in
figure 2 of BS 7121 : Part 1: 1989;
f ) capable of giving precise and clear verbal
instructions where audio equipment (e.g. radio) is
employed, and capable of operating such
equipment in accordance with 19.2.
7.7 Crane erection supervisor
The crane erection supervisor should have the same
attributes as the crane erector and:
a) have at least five years’ experience in the
erection and dismantling of tower cranes or
similar equipment, and be trained in the
supervison of such operations;
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S T D - B S I B S 7121: P A R T 5-ENGL 1777 W Lb2YbbS Ob25Y38 4 2 T
BS 7121 : Part 5 : 1997
b) be fuily conversant with the manufacturer’s
instruction manual for the particular crane (see
note);
c) be trained in the control of personnel carrying
out the duties of erecting and dismantling tower
cranes, and in ensuring that all persons use their
personal protective equipment correctly;
d) have knowledge of the certification
requirements for all equipment used.
NOTE.The crane erection supervisor should be in possession of
the manufacturer’s instruction m u a i for the particular crane.
8 Selection of tower cranes
8.1 General
Selection of a tower crane for a particular liftiig
operation should be considered by taking the
following into account
a) clause 7 of BS 7121 : Part 1: 1989;
b) prevailing wind-speeds, which can restrict the
use of tower cranes in certain locations;
c) principal features of the common types of tower
crane, as described in this Part of BS 7121.
NOTE. Sîatic and mobile tower cranes are available in a wide
variety of types and conñgwations according to the particular
combination of tower, jib and type of base which they employ.
individual cranes can comprise almost any combination of the
features shown in figures 1 , 2and 3.
8.2 Types of tower (see figure 1)
Tower cranes have either a non-slewing or slewing
tower. With a non-slewing tower, the slewing ring is
situated at or near the top of the tower and the jib
slews about the vertical axis of the tower, which
itself remains stationary. With a slewing tower, the
slewing ring is situated at the bottom of the tower
and the whole of the tower and jib assembly slews
relative to the base of the crane.
Where non-slewing towers have to be tied to a fixed
structure, it is imperative that the manufacturer’s
instructions are followed. The ties should be
designed by a competent person to withstand the
loads specified by the manufacturer, and be attached
to a structure capable of withstanding the imposed
loads.
8.3 Types of jib (see figure 2)
8.3.1 Horizontal trolley j i b
The jib is held by tie bars or ropes in a horizontal or
slightly raised position, and the hook is suspended
from a troiley which moves along the jib to alter the
hook radius. A suitable allowance needs to be made
for deflection when calculating the clearance
between adjacent cranes (see 4.2.2).
8.3.2 Inclined trolley j i b
The inclined trolley jib is similar to the horizontal
trolley jib except that the jib may be set at a
significant angle of inclination.
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8.3.3 L m n g j i b
The jib angle can be changed to reposition the load
at various radii. The jib may be single- or
multi-component, and if multi-component, may be
articuiated (goose necked) or telescopic. Due to the
varying out-of-service conditions for these cranes
particular care should be taken to observe the
manufacturer’s instructions (see 12.4b).
8.3.4 Fixed radius j i b
The radius at which the load is carried cannot be
varied. Fixed radius jibs are usually only available on
small tower cranes (self-erectors and similar), and it
is generally desirable to be able to travel the crane in
order to move the load.
8.4 Types of base (see figure 3)
8.4.1 Expendable base
The crane is mounted on special foundation anchors
or an expendable tower section, cast into a concrete
foundation block. (see figure 3d).
NOTE. It is important that the foundation anchors or expendable
tower section are installed withii the maker’s tolerance of
accuracy to ensure that the erected crane is within operational
limits.
8.4.2 Crane base structure
The crane stands on its own base structure with
ballast (cil1 base) or with its base structure bolted
down to a concrete foundation block (cruciform
base). With this arrangement a larger area of ground
floor space is taken up and, therefore this type of
base is not always acceptable on small sites.
Where the base is secured by ballast blocks there
should be a notice attached detailing the position
and weight of the blocks, and that the blocks should
be adequately secured to prevent accidental
displacement. The ballast arrangement should not be
altered after the crane has been tested, for
constructional or any other reasons (see 9.4.10).
8.4.3 Non-crane structure
A base provided by a structure which is not a normal
part of the crane (e.g. part of a bridge, a building or
structure provided specifically for such a purpose).
8.6 Types of tower crane
8.6.1 Climbing crane
A climbing crane is a tower crane that may be
altered in height after initial erection. Where the
crane remains on its original base this may be
achieved by the use of internal telescoping
equipment or external climbing frames. Another type
of climbing crane can ascend through a structure
using a climbing frame, the supported crane being
provided by the surrounding structure.
NOTE. This type of crane requires less initiai outlay due to the
reduced quantity of mast required, but it has disadvantages in that
the stnicture needs to have adequate strength and rigidity to carry
the imposed loads, and the mast through the middle of the
structure may interfere with the completion of the structure.
Consideration should also be given to the dismantling of the crane
once the structure is completed.
3
8.6.2 Rail mounted tower crane
A rail mounted tower crane is mounted on a chassis
frame which is supported on rail wheels which are
usually double flanged. There can be four single
wheels on smaller machines or more usuaiiy four
double wheel bogeys. The wheels or bogeys can
have special mountings to enable the crane to
negotiate bends. Rail mounted tower cranes may be
of any of the types described in 8.2 and 8.3. Stability
is normally obtained by means of ballast weights
which should be adequately secured to prevent
accidental displacement or removal, and the detail of
the ballast should be on the notice near the base of
the crane giving the crane capacities.
NOTE.Rail tracks for tower cranes are in 10.3.2.
0.6.3 Lorry mounted tower crane (see figure 4)
A lorry mounted tower crane is mounted on a truck
or lorry chassis. These are particularly suitable when
considerable inter-site mobility is required. Extra
care should be taken in ensuring that outriggers,
jacks, etc., are adequately supported for their
imposed loads.
8.6.4 Wheel mounted tower crane
Some very small capacity tower cranes are available
on trailer mounts with pneumatic tyres. These
machines need to be towed into position and should
be properly mounted on their outriggers or jacks
before erection or use. The manufacturer's erection
instructions should be scrupulously observed and if
the operator is to erect and dismantle this type of
crane, he or she should be specifically trained and
have the athibutes of an erector (see 7.4).
0.6.6 Crawler mounted tower crane
Some tower cranes mounted on a crawler base have
means of self-levelling. They are equipped with a
sensing device to detect verticality. The seif-levelling
function has a limited range of correction and great
care should be taken when travelling over uneven
ground. Crawler mounted cranes without
self-levelling should not be moved over uneven
ground when erected.
8.6.6 Micro tower crane
Micro tower cranes are tower crane units complete
for mounting on the top of either a special mast or a
hoist mast. "hey usually have a radius of
approximately 6 m, a safe working load always
under 1000 kg and are remote controlled. Micro
tower cranes are generally used for offloading
materials and placing within a limited area of a
building.
8.6 Remote controls
Where cranes are available with remote controls,
care should be taken in their use for the following
reasons.
a) The crane driver has no 'feel' for the machine
and could, under certain circumstances, be
tempted to handle the machine more dangerously
than if the crane were operated via a cabin
control.
b) Infra-red remote control may be unreliable on
tower cranes if the receiving sensor rotates with
the crane and thus loses alignment with the
transmitter.
NOTE. Remote controls have one main advantage in that the
crane driver can be at a point of safety when the crane is in use,
especially during overload testing.
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STDmBSI BS 7121: P A R T 5-ENGL 1 9 9 7
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BS 7121 : Part 5 : 1997
a) Fixed tower
b) Slewing tower
Figure 1. Types of tower
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BS 7121 :Part 5 : 1997
Fweá section of tower
\
a) Saddle (horizontal) jib
b) Luffing jib
Figure 2. Types of jib
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/-
Trolley moves along boom
1
*
m
*
c) Fïxed jib
d) Rear pivoted luffing jib
Figure 2. Types of jib (continued)
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Sleepers
\
Rail
I
a) Travelling base (raii type)
b) Cill base
Figure 3. Types of base
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Ballast weights
Cruciform base ballasted
/
Anchorage fixings
*
Co
*
Cruciform base unballasted
c ) Cruciform base
of crane tower
FMed
d) Expendable base
Figure 3. Types of base (continued)
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BS 7121 : Part 6 : 1997
Figure 4. Lorry mounted tower crane
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9 Safety
9.1 General
Reference should be made to clause 8 of BS 7121 :
Part 1: 1989.
9.2 Personal protective equipment
9.2.1 Personnel whose duties include working at
heights on tower cranes should be provided with the
necessary safety equipment, e.g. safety harnesses, as
well as lifelines or similar equipment to attach to
safety equipment.
Such personnel should be instructed in the correct
use and maintenance of such equipment and
instruction should be given regarding the specific
occasions and circumstances when these items are
to be used.
which may interfere with each other’s freedom of
movement. Such devices should limit the slew, the
trolley motion, or the travel motion of the crane to
ensure that coilision between the structure of one
crane and the rope or load of another crane is
impossible.
NOTE.It may be considered preferable to have these devices
equipped to warn or give information to the driver, rather than
interfere with the operation of the crane.
Where t r a g cables run between one crane and
another, consideration should be given to the means
required to protect them adequately against
interference or accidental damage.
9.6 Other safety provisions
9.6.1 Lightning protection
Tower cranes should be completely and correctly
earthed.
Reference should be made to BS 6651 and BS 7430.
9.2.2 Personnel should be advised when and where
helmets should be worn with respect to the
Construction (Head protection) Regulations, 1989 [i]. 9.6.2 Base ballast design
Heimets with chin straps should be used when
When concrete ballast needs to be provided,
working at heights.
particularly in the case of new tower cranes, it is
important that the ballast should either:
9.2.3 Personnel working on tower cranes should
wear suitable footwear for climbing structures.
a) have been constructed in accordance with the
crane manufacturer’s design and specification; or
9.3 Fire extinguishers
b)
be of a design which has been approved by the
Reference should be made to 8.6 of BS 7121 :
crane
manufacturer, and effectively secured.
Part 1: 1989.
Only
ballast
blocks having markings showing their
Tower cranes should be equipped with appropriate
correct
weight
should be used.
types and quantities of fire extinguishers, which
should be easily accessible to the driver.
9.6.3 Counterweight ballast
The driver and any other personnel likely to be in
Counterweight ballast should be constructed and
the cab should be adequately trained in the use of
marked in accordance with 9.6.2. Since the
such fire extinguishers.
counterweight ballast is at height and the blocks
have a tendency to rub together during crane
9.4 Crane safety equipment
operation, precautions should be taken to prevent
Tower cranes should be provided with the following spilled concrete from falling (e.g. by containment in
as a minimum:
a metal box or frame).
a) automatic safe load indicator, in accordance
9.6.4 Alarms
with 8.7.1 of BS 7121 : Part 1 : 1989;
R
ail mounted tower cranes should be fitted with an
b) load radius indicator, in accordance with 8.7.2
audible
travel alarm.
of BS 7121 : Part 1: 1989;
c) motion limiting devices, in accordance with
9.6 Documentation
8.7.3 of BS 7121 : Part 1 : 1989
9.6.1 General
d) overload cut-out devices, in accordance with
Reference should be made to 8.8 of BS 7121 :
8.7.4 of BS 7121 : Part 1 : 1989
Part 1 : 1989.
e) level indicator, in accordance with 8.7.6 of
BS 7121 : Part 1: 1989;
9.6.2 Erectioddismantling and transport
f ) anemometer, in accordance with 8.7.6 of
All stages of transportation, erection and dismantling
BS 7121 : Part 1: 1989;
of tower cranes should be thoroughly documented
g) machinery guarding, in accordance with 8.7.7
from initial enquiry to the final acceptance by the
of BS 7121 : Part 1: 1989;
user organization.
h) zoning devices.
9.6.3 Drivers’ documentation
Zoning devices may be applied to a single tower
Records should be kept of tower crane drivers’
crane where there is an area which it should not
training and experience, including such certificates
oversail during operation, or over which it should
of training as may be available.
not cany loads. The principal use of zoning devices,
however, is where there are two or more cranes
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9.6.4 Medical records
Records should be kept of any medical examination
for lifting operations personnel.
9.6.6 Plans and method statements
The plan or method statement for the erection of
tower cranes should be retained throughout the
duration of a crane’s service on any one contract,
together with calculations and plans for the tower
crane base.
NOTE. It may be necessary to refer to these in the event of a
change of construction in the come of the contract requiring
alterations to be made to the crane.
9.7 Access and cab safety
9.7.1 General
if personnel need to be present on the crane whilst
the machine is in use, they should always inform the
driver.
NOTE. It is recommended that access to tower cranes should be
prohibited to personnel whose presence is not essential, wherever
possible.
9.7.2 Crane access
The appointed person should ensure that ladders,
rest platforms and other means of access are in
accordance with current regulations and standards.
The erection supervisor should ensure that access
equipment is correctly installed progressively as
erection proceeds, so that the erection team have the
benefit of their use. Particular attention should be
paid to:
a) ladder joint bolts,
b) guard rails, particulaxly on rest platforms and
inspection platforms;
c) access from ground to the foot of the lowest
ladder or to the chassis of the crane;
d) access from levels of the construction to the
crane.
9.7.3 Jib and counterjib access
Access to and along jibs and counter jibs for
inspection and servicing should be made safe.
Catwalks should be provided with handrails. Where
lifelines are provided, a suitable device should be
used in codunction with the harness to permit full
passage along the jib without detachment.
NOTE. Personal carrying cages attached to the trolley may
provide suitable aiternative safe access along the jib.
9.7.4 Cab sqfety
The appointed person should verify that:
a) vision panels in the floor of cabs or at the
driver’s feet, in such a position that they may have
to withstand all or part of the driver’s weight, are
guarded, for example by a mesh of adequate
strength to carry a person’s weight over the area
concerned;
b) window panels in walls of cabs are protected
against being knocked outwards to prevent
persons falling through the aperture;
c) panoramic and similas cabs of which the top
part may be opened, conform to the Construction
(Work places) Regulations, 1966, Regulation 28 [3].
10 Siting of cranes
10.1 General
Reference should be made to clause 9 of
BS 7121 Part 1: 1989. Attention is drawn to 4.2.2 of
this Part of BS 7121.
10.2 Ground conditions
Where tower cranes are to be erected close to the
foundations of existing buildings or buildings to be
constructed, the appointed person should ensure that
the ground is consolidated as required by the
designer.
Where disturbance to the ground has occurred in the
construction of adjacent foundations, a retaining wall
should be constructed or deeper foundations used
for the tower crane.
10.3 Tower crane foundations
10.3.1 Expendable base blocks
Minimum dimensions for any expendable base block
together with the overturning moment and other
loadings during operation and out-of-service
conditions should be as specified by the crane
manufacturer.
Having obtained from the crane manufacturer the
loads imposed by the crane (noting that these may
be nett and exclusive of any impact of safety
factors), the foundation should be designed by a
competent engineer so that the ground bearing
capacity is not exceeded, including that caused by
overturning moments.
Where the base design limits the free standing height
of the crane, the maximum permitted free standing
height should be marked at the base of the crane
and entered into the documentation.
10.3.2 Rail tracks f o r tower cranes
Rail track should be made of suitable materials and
strict control should be exercised to ensure that it is
not in any way abused.
NOTE. Rail track requires expertise in its design, layout and
installation, particuìarly if it is to be curved.
The area between the tracks should never be used
for the storage of materiais or for access to, from or
across the site. The total area of the rail tracks
should preferably be fenced off to prevent access by
unauthorized persons.
If there needs to be a point at which vehicles cross
the rail track, this should be carefully controlled to
prevent accidental collision, and precautions should
be taken to ensure that the track is not overloaded
by the vehicles crossing it.
The gauge of rail tracks should be maintained by
suitable means, e.g. tie bass.
Rail tracks should not be welded or subjected to
heating.
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End stops or buffers should be positively futed to the
rail and precisely adjusted to ensure that the crane
makes contact with both sides simultaneously. These
end stops should be shock absorbing or sprung, and
should be moved hard against the crane chassis if
the machine is to be used in a static position for any
period of time. Rail stops should not be taken into
account when calculating the stability of the
machine.
Rail clamps which the crane manufacturer may
provide to prevent the crane fi-om roiling along the
track in storm conditions should be fitted whenever
the machine is out-of-service. If clamps are not
supplied, adequate means should be adopted to
achieve the same result.
Rail tracks of all types require periodic inspection,
and should any defect or out-of-level become
apparent, corrective action should be instigated
immediately.
11.3 Control
In the case of erection and dismantling of tower
cranes, the person appointed to control the lifting
operation should also take control of any additional
crane which may be used in the course of such an
operation, and be familiar with details of that crane,
to facilitate the carrying out of the duties, as detailed
in 3.2 and 3.3 of BS 7121 : Part 1 : 1989.
He should also ensure that the operation is under the
constant supervision of the crane erection
supervisor.
11.4 Planning for erection and dismantling
NOTE 1. The plan for the erection and particuiarly the dismantling
of tower cranes requires careful consideration. Most organizations
who erect tower cranes, either for themselves or for others, utilize
some form of pro forma or check list to ensure that nothing has
been overlooked at the planning stage.
A plan for the erection or dismantling of tower
cranes should be drawn up by a person or persons
having
actual experience of these operations. The
10.3.3 Special base
plan should deal with the following:
Where the particular application calls for a special
a) the format in which the crane is to be
base arrangement, e.g. structural steelwork, then the
transported
to the site;
appointed person should ensure that the base k.
b) the selection of cranes that will be required to
a) designed by a competent engineer, allowing for
assist in the erectioddismantlingprocess,
any appropriate factors (e.g. impact, dynamic),
especially considering the removal of components
with the details of the design verified by a
from
a height; e.g. when removing a section such
competent third party;
as
a
jib from an erected tower crane, the assisting
b) constructed in accordance with the design.
crane wiil be carrying the entire load with no
opportunity for safely replacing it once the
attachment pins have been removed. in this case it
11 Erecting, dismantling and
may
be desirable for the crane to have some
alteration of height
excess capacity to allow for any error in the
11.1 General
slinging of the component concerned or its sudden
release. Under no circumstances should the crane
Reference should be made to clause 10 of BS 7121 :
used in the dismantling operation be used to break
Part 1 : 1989.
a load free. A method of jacking should be used to
Erection, dismantling and alteration of height of
prise
the load free after the initial tension is taken
tower cranes should not be undertaken after dark.
by the crane;
11.2 Personnel
c) the availability of access to the site for the
vehicles involved in transportation as well as the
The erection, dismantling and alteration of the height
crane(s) used for erection;
of tower cranes should be carried out by specialist
personnel under the continuous control of the crane
d) the ground conditions for the erecting crane;
erection supervisor and in accordance with the
e) the free standing height to which the crane will
manufacturer’s instructions. This supervisor should
be
erected
be given the authority to stop the operation if he or
f
)
proximity
hazards. Attention is drawn to 9.3 of
she considers such action is warranted by ground
BS
7121
P
a
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1: 1989;
conditions, weather, obstructions or any other cause.
g) any specialized Wing gear that will be required
The crane erection supervisor should be in close
in the course of this erection;
liaison with the site management and should
carefully consider any comments or warnings that
h) liaison with occupiers of neighbouring
management, any members of the site team, or any
properties;
other appropriate person or body may make.
i) contact with local authorities or other bodies
NOTE. The management may consider that this supervisor is the
requiring statutory notification;
appropriate person to be appointed to control any lifting
j)
arrangements for any necessary road closures;
operations (see 3.2 of BS 7121 : Part 1 : 1989).
k) the provision of a radio licence where required,
available from the appropriate authorities;
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BS 7121 :Part 5 : 1997
1) the availability on site of a comprehensive
maker’s erectioddismantlingloperationmanual, in
the language most readily understood by the
erection team.
NOTE. It is desirable that this information is available in advance
of the operation so that the personnel concerned may familiarize
themselves with the content.
11.6 Inspection before erection
All parts should be inspected prior to erection to
ensure they belong to the crane being erected and
are in good condition, free from defect.
Slinging points should be identified for all
components.
NOTE. Under certain circumstances it may be advantageous to
carry out an inspection of the tower crane before it is delivered
from the supplier to the user.
11.6 Weather
Tower cranes should not be erected or dismantled in
weather conditions likely to affect the stability of the
crane, e.g. high winds (reference should be made to
the manufacturer’s instructions for the maximum
permissible wind speed for these particular
operations) or under conditions of impaired
visibility, e.g. fog.
NOTE. More stringent restrictions on wind speed appiy to
heightened cranes.
This type of work should be avoided if the
conditions (e.g. ice on component parts, walkways)
are likely to endanger the erectors.
11.7 Manufacturer’s erection and dismantling
instructions
Reference should be made to 10.2 of BS 7121 :
Part 1: 1989.
NOTE. Many tower crane manufacturers lay down specinc
inspections and checks to be canied out in their erection and
dismantling manual. For example, it is important to ensure that
the lubrication requirements of tower joint bolts are met before
applying torque.
11.8 Components and materials
11.8.1 Interchangeabilitu of components
The interchange of structural components between
one tower crane and another should onìy be
permitted if the manufacturer has given approval.
Having carried out such an interchange, a tower
crane should be retested in its new combination, and
the interchanged parts should be specified on the
test certificate.
11.8.2 Materials
Most tower crane parts are made from special steels
and no repair or replacements other than
manufacturer’s specification should be permitted.
Welding or other heat treatments should be carried
out under the manufacturer’s specified conditions.
The re-use of high tensile bolts should be strictly in
accordance with the manufacturer’sconditions.
High strength friction grip bolts should not be
re-used.
Bolts used to secure slew races should be renewed
whenever they are removed. They should only be
tightened in accordance with the manufacturer’s
instructions.
11.9 Working area
The area in which a tower crane is to be erected or
dismantled should be roped or fenced off and all
personnel not immediately connected with this duty
should be excluded.
12 Procedures and precautions
12.1 General
Reference should be made to clause 11 of BS 7121 :
Part 1: 1989.
12.2 Working on cranes
For tower cranes likely to sway or slew in the wind,
appropriate precautions should be taken to prevent
people from being displaced from their place of
work by this movement, or being trapped by a
rotating centre section of a tower crane under such
conditions.
12.3 Working at heights
A safe system of work should be used, in accordance
with 3.1 of BS 7121 : Part 1: 1989.
12.4 Leaving the crane unattended
When a tower crane is to be left unattended for even
a short period, it is essential that the following
precautions are carried out.
a) No load should be left on the hook, and all
chains, slings, etc. should be removed.
b) The crane should be put out of service in
accordance with the manufacturer’s instructions.
NOTE 1. In nearly every case, this will involve turning the jib
downwind and taking some action to ensure that the slew
brake is left off, so that the crane is free to slew in the wind.
NOTE 2. In the case of saddle jib cranes it is usual practice to
bring the trolley or carriage to a minimum radius position.
Tower crane jibs may infringe air space when left in the
out-of-service condition.
c) In the case of luffing jib and similar cranes, the
manufacturer’s instructions concerning the angle
of the jib for out-of-service purposes should be
strictly observed (see 8.3.2).
d) Rail travelling cranes should be well secured to
the rails, to make sure that in the event of a high
wind the crane cannot be blown accidentally along
the rails. When left for long periods (e.g.
overnight), the power supply to the crane should
be cut off and the door of the cab secured and
locked.
e) When a power supply is required to be
maintained overnight for cab or control cabinet
heaters, lights etc., separate arrangements should
be made for the isolation of the power supply to
the machinery.
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13 Operating conditions
13.1 General
Reference should be made to clause 12 of BS 7121 :
Part 1: 1989.
13.2 Mode of operation and control
As the most common variation in mode of control
encountered between different makes and models of
tower cranes is the procedure for stopping the
slewing motion, it is essential that the crane driver is
made aware of which method of Carrying out this
duty is applicable.
NOTE. Failure to use the correct method can result in excessive
structuraì stress on the crane as weii as causing failure in the
electrical systems.
It is strongly recommended that the largest
practicable bold notice should be displayed in the
cab (in addition to the manufacturer’s instruction
book) detailing the method of stopping the slew.
13.3 Multiple lifting
Tower cranes should not be used for multiple lifts.
13.4 Special duties
Tower cranes should not be used for carrying out
special duties such as grabbing, lifting by magnet,
balling operations, pile driving, or extracting.
13.6 Vacuum lifting devices
Reference should be made to 12.6.3 of BS 7121 :
Part 1: 1989.
Tower cranes may be used with vacuum liftiig
devices provided that the weight of the device plus
the weight of its load does not exceed the safe
working load of the crane.
NOTE. The manufacturer may recommend some de-rating of
cranes for this duty.
13.6 Weather
13.6.1 General
No crane should be used or erected under weather
conditions likely to endanger its stability.
Reference should be made to 12.6 of BS 7121 :
Part 1 : 1989.
Attention is drawn to 11.6 of this Part of BS 7121.
13.6.2 Wind
The manufacturer’s in-service wind speed should be
strictly observed and cranes should be put out of
service in accordance with the manufacturer’s
instructions as soon as this wind speed is reached.
In-service wind speeds should be carefully checked
in the manufacturer’s instructions before putting a
crane into operation.
13.6.3 Snow and ice
Heavy accumulations of ice can make access along
the jib extremely hazardous, and under these
conditions consideration should be given to not
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starting work with the crane until the temperature
has risen sufficiently to cause a natural thaw.
Personnel in the vicinity should be warned of the
likeliness of large lumps of ice falliig during the
thawing.
NOTE 1. Horizontal jib tower cranes are more prone to excessive
loading from snow and ice than most other types of crane.
NOTE 2. When there has been an excessively heavy fall of snow
this should be carefully removed from the jib and counterweight
jib before putting the crane into service.
13.6.4 Examination following adverse weather
conditions
After exposure to weather likely to have affected the
stabiiity of a crane, the anchorage arrangements and
ballast should be examined by a competent person
as soon as practicable and before the crane is used,
and any necessary steps taken to ensure the stability
of the crane.
NOTE. Attention is drawn to The Construction (Lifting operatioos)
Regulations, 1961, Regulation 19 (7) [2].
Whilst the above examination is being carried out
the whole structure should be adequately inspected
to ensure that it has not suffered any damage or
condition likely to lead to failure in the course of
bad weather.
14 Testing and examination
14.1 General
Reference should be made to clause 13 of BS 7121 :
Part 1: 1989.
Clause 14 of BS 7121 : Part 2 : 1991 should be studied
in detail before any attempt is made to test a tower
crane.
14.2 Age and utilization
Tower cranes are not designed for a high intensiw of
usage. Should a crane have been subjected to such
usage, consideration should be given to the use of
non-destructive testing to detect possible fatigue
cracking. The assistance of the manufacturer or
design authority should be sought to determine the
vulnerable parts of the structure.
Usage or storage of the crane in a corrosive
environment may also cause deterioration of the
crane structure and this may require more extensive
examination.
Fatigue damage and corrosion are also likely to be
present on older tower cranes, which may require
more detailed examination and testing as described
above.
Older cranes may remain serviceable, but particular
attention should be given to these aspects on cranes
more than ten years old.
14.3 Certification of cranes
Reference should be made to 13.1.2 of BS 7121 :
Part 1: 1989.
15
14.4 Personnel safety
Attention is drawn to 3.2.4 of BS 7121 :
Part 2 : 1991 which points out that a test may fail and
all personnel not essential for the test should be kept
away from the area In this connection, it should be
noted that if a crane is equipped with remote
control, then this should be used for the purpose of
carrying out the test with the driver in a safe
position.
Attention is also drawn to clause 14 of BS 7121 :
Part 2 : 1991 which recommends that a clamp or
similar device should be attached to the jib to limit
the radius of the trolley when carrying out a
maximum load test. Where safe access is not
available to fit or remove the clamping device
alternative safe means of limiting the radius of the
tsolley should be adopted.
19 Signalling systems
19.1 General
Reference should be made to clause 19 of BS 7121 :
Part 1: 1989. Due to the distance between tower
cranes and other personnel it is important that clear
systems of identification and communication are
used.
Attention is drawn to 8.2 of BS 7121 : Part 1: 1989.
19.2 Radio communications
Guidelines are given in annex A.
20 Tying and guying
16 Ropes
In certain circumstances a crane should be tied to
the structure it is constructing, or held by guy ropes
for any one of the following reasons:
a) to obtain a height in excess of the available
free-standing height;
b) to restrict the movement of the tower when
available space is limited;
c) to comply with the requirements of the
occupiers of adjacent properties, e.g. railways.
In any of these cases the tyindguyjng arrangements
should be in accordance with either the
manufacturer's approval or calculations carried out
by a competent engineer.
Reference should be made to clause 16 of BS 7121 :
Part 1: 1989.
21 Signboards
15 Legal requirements
Reference should be made to 14.1 and 14.3 of
BS 7121 : Part 1: 1989. With regard to specific
legislation, users of this Part of BS 7121 should
acquaint themselves with the current national
legislation that applies to the provision, maintenance,
examination and use of tower cranes.
17 Slinging and handling of loads
Reference should be made to clause 16 of BS 7121 :
Part 1: 1989.
18 Raising or lowering of personnel
Reference should be made to clause 17 of BS 7121 :
Part 1: 1989.
Tower cranes generally conform to the statutory
requirements for raising or lowering of personnel by
cranes, but due to the extra height often involved,
special care should be taken to prevent the swing of
the cradle carrying personnel, which could, in turn,
cause the cradle to spin. It is not generally
practicable to attach a tag line or similar equipment
to such a cradle, and it is suggested that a cradle
which is rectangular or square in plan would be
easier to control when bringing it alongside a
structure or building on which the occupants may be
required to work.
Care should be taken to ensure that the cradle is
kept clean and in good condition and is not used to
carry any tools, loads or equipment which may make
a foothold difficult for the occupants.
Signboards, decorations, outline lights, etc. can
impose additional loadings on the crane and should
not be fitted unless approved by the crane
manufacturer.
Electrical supplies to such equipment should be
restricted to 55 V max. Wiring should be protected
to
against damage and should not create a h-d
personnel.
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Annex A (informative)
Specimen copy of information sheet
RA 196 published by the Radio
Communications Agency
NOTE.This publication is reproduced here for the convenience of
the reader, but the reader is advised to check if this has been
superseded and, if so,use the latest edition issued by:
The Raàiocommunications Agency
South Quay Three
189 Marsh Wall
London E14 9SX
Safer radio techniques
Radiocommunications for ‘hwer Cranes
Introduction
%wer cranes often require communication as a means
of signailing to ensure safe operation. This infomation
sheet provides advice on the use of radio.
Radio installation and operation in this environment
calls for the observance of special requirements. Any
radio system mounted high up on a stnicture is likely
to receive and cause interference to other users over a
wide radius unless it is carefully engineered. Since
there are only a limited number of radio channels
available, it is likely that a crane will be sharing a radio
frequency within the same conurbation, and in worst
cases on the same construction site. It is necessary,
therefore, to engineer a ‘clear’ channel.
A number of approved techniques have been
developed to provide clear channeis. The consequence
of not adopting one or more of these is that safety of
life could be put at risk both on the construction site
and elsewhere for other services using radio.
The Problem
When a radio is used at ground level surrounding
buildings and ground clutter soak up some of the
signals and reduce the distance over which the signais
can be received Any radio located high up on a crane
is able to lmnsmit into free space and will be
receivable many miles away
At first sight this does not seem too much of a
problem as most of the t a l h g is done by the
banksman and the crane driver is mainly listening.
However, not every banksman is located at ground
level and often he wiìl obtain just as good propagation
as the crane driver.
W o communications between banksman and
controller pose different propagation problems as
constsuction progresses. On the construction site, the
building itself may act as an obstacle to proper radio
communication and it may not therefore be possible to
reduce the output power to prevent interference to
others. Often reducing output power does little to
contain transmissions into free space but prevents
communication into parts of the building such as a lift
Shaft.
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Although, as the building goes up, the b a n h m wiii
increasingly be liable to transmit nom a raised position
he could stiU have transmissions blocked by the
building in a particulas direction. The crane is likely to
be above the construction and able to freely transmit
in all directions throughout the duration of the work
The area where it will be hardest to penetrate is the
opposite side of the building should it be necessary to
operate in that area
~
1) Signalling systems
The use of CESS (Continuously Tone Controlled
Signalling System) or another form of Signalling
will help lessen the effects of sharing. They can
not, however, soive the problem. As a crane wiil
receive signals from a large catchment area, tones
will oniy reduce the transmisions which the
crane driver has to listen to.
2) Special techniques
There are several engineering techniques available
which will alleviate the problems. These range
from directional antenna or other means to
restrict range which confine the radiation
verticaiiy between operator and banksman to
Merent types of communication on the up and
down paths.
It is possible to superimpose the radio traffic over
the mains voltage. A leaky feeder from the rear jib
will limit the radiation pattern. Whilst these are
excellent solutions it should be noted that both
systems have been patented.
The use of a magmount aerial, because it is omnidirectional, will freely radiate. This causes
problems in that communications wili be
transmitted and received over a wide area. It is,
therefore, essentiai to reduce as far as possible the
radius for both transmission and reception.
3) Call signs
One very simple way to improve the safety
aspects of radio communication is to use call
signs at the start of the message. When there is a
danger that a radio frequency could be shared
with another crane, and messages wili be of a
similar nature, a unique call sign is a useful tool to
ensure that a message is acted upon only by its
intended recipient. Another reason why they
should be used is that when an interference
complaint is received, the Radio Investigation
Service can more easily identify the users involved
when call signs are used. There is much that
contractom could do to help by ensuring their
crane operators use call signs and explaining the
benefits to them. It is &o a licensing requirement.
17
BS 7121 :Part 5 : 1997
me of n'equency
The Agency can allocate either a single or dual
frequency channel. If a crane is going to be at a site
for a considerable amount of time the user will require
a licence and it wili be necessary for the Agency to
assign a channel. However, if the duration of the
contract is less than twelve months, equipment may be
hired from a Short Qrm Hire licensee.
Licensing requirements
The use of all radio must be licensed but users are free
to choose either a single or dual frequency and the
system employed The Radiocommunications Agency is
not concerned about which particular system is chosen
provided that interference to other users is kept to a
minimum. Engineering trials have shown that it is
possible to share frequencies much closer than had
previously been thought possible providing the systems
are carefully engineered.
In defining what does or does not cause unacceptable
interference, it has been decided to define a maximum
signai strength at a distance from a crane no matter
which techniques are employed. This shall be a
maximum of 48 dB/uv per metre measured at 2 lan
h m the crane at a height of 3 m above ground level. It
is not intended that every crane radio should be
required to conform with this figure. It would not, for
example, be necessary in areas of the UK where use of
radio communications is relatively light. However, if an
interference complaint is received, and the offendmg
radio system does not conform to these parameters
then it will be necessary for that system to be
reengineered so that it does conform.
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O BSI 1997
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S T D - B S I BS 7121: P A R T 5-ENGL 1797
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BS 7121 : Part 6 : 1997
List of references ( ~ e eclause 2)
Normative references
BSI publications
BRiTïSH STANDARDS INSTITUTION, London
BS 6651 : 1992
BS 7121
BS 7121 : Part 1: 1989
BS 7121 : Part 2 : 1991
BS 7121 : Part 4 : 1997
BS 7430 : 1991
Code of practice for protection of structures against lightnirq
Code of practice for safe use of c r a m
General
Inspection, testing and examination
Lorryloaders
Code of practice for earthing
Informative references
[ 11 GREAT BRITAIN. The Construction (Head protection) Regulations, 1989. London: HMSO.
[2] GREAT BRITAIN. The Construction (Lifhng operations) Regulations, 1961. London: HMSO.
[3] GREAT BRJTAIN. The Construction (Work places) Regulations, 1966. London: HMSO.
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COPYRIGHT British Standards Institution on ERC Specs and Standards
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BS 7121 :
Part 5 :1997
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